Heat supply in cities with buildings above two floors is carried out centrally. For heating and hot water supply of residential and public buildings, water transported from heat supply sources to consumers through heating networks is used as a heat carrier.
Heating networks are laid outside the carriageway of streets and roads, as well as outside the strip of green spaces. The laying of heat networks is carried out underground without channels with the deepening of pipelines by at least 0.7 m to the top of the thermal insulation.
The working pressure of the coolant in water networks is taken according to the highest pressure in the supply pipeline, but not less than 0.98 MPa (10 kgf / cm2). The house heating system is connected to the city (district) heating pipelines through a heat input located in the basement of the building.
It is advisable to combine central water heating with hot water supply.
Water central heating systems can be single-pipe and two-pipe, with natural (gravitational) circulation of the coolant or with artificial (mechanical) stimulation of its circulation, with upper and lower wiring.
Single pipe it is more economical to use a central heating system in comparison with a two-pipe system in buildings with a height of more than three floors. With less piping, they require the installation of a larger number of radiator sections.
Two-pipe DH systems with natural circulation are usually arranged with overhead wiring, when the main pipelines are located in the attic or under the ceiling of the upper floor of the building. With the upper wiring, the removal of air released from the water when it is heated is simplified. In buildings of great length (along the facade, or perimeter), it is not economically viable to install central heating systems (because of the need to use large cross-section pipelines to move the required amount of water). For this, an additional pump is included in the network.
The circulation pressure in systems with bottom wiring is less than in systems with top wiring. Therefore, with natural water circulation, systems with an upper wiring are preferable.
To heat water in apartment central heating systems, radiators, coils embedded in stoves or stove chimneys, as well as small cast-iron and steel boilers are used. Household heating and water-heating and heating-cooking devices are also used.
In apartment water heating systems and in one-pipe vertical central heating systems with natural excitation, it is allowed to install a heat generator and heating devices on the same level. Heating of staircases for buildings below three floors is not provided. The laying of pipelines of central heating systems should be made open. In residential and public buildings, it is recommended to provide for the placement of risers of central heating systems in the corners formed by the external enclosing structures.
Supply and return pipelines of central heating systems of residential and public buildings are laid in basements, technical floors, attics, undergrounds (except for buildings located in the northern climatic zone), under the floor of the first floor (in channels) and above it (with upper wiring of supply pipelines).
In public and industrial buildings, low-pressure steam heating systems (up to 0.07 MPa) and high-pressure steam heating systems are used. Low pressure steam heating is more commonly used.
In water and steam central heating, heating devices are used - radiators, finned pipes, convectors and rarely concrete heating pipes.
Radiators are produced cast iron and stamped steel.
Cast iron radiators are assembled from separate hollow sections, the holes of which on one side have a right-hand thread, on the other - a left-hand thread. Cast iron heaters are designed for a working pressure of 0.6 MPa
Steel radiators made of two stamped sheets connected by contact welding, steel radiators - for a pressure of 1 MPa.
The maximum water temperature in heating devices of residential and public buildings should not exceed 95 ºС, except for nurseries, kindergartens, hospitals and maternity hospitals, where the maximum temperature is 85 ºС. Heating devices can be closed with decorative grilles.
heating device requirements:
· High heat transfer coefficient;
High heat stress of metal;
Compactness of the surface of the device;
Easy removal of dust from the surface of the device;
These requirements are best met by radiators, so they are widely used in buildings for various purposes.
Ribbed tubes and convectors are used for heating stairwells and basements, sports facilities, domestic premises, baths, laundries and industrial premises with a slight emission of dust. Registers are installed in industrial premises with significant dust emissions.
Pipelines hot water supply mounted from galvanized steel water-gas-wire pipes on threaded connections using elbows, tees and other fittings. On the branches from the main pipelines, at the bases of the supply and circulation risers (in buildings with a height of three floors or more), on the branches to each apartment or supplying five or more water points, valves are installed with sealing gaskets in valves made of heat-resistant material such as fiber. Mixers designed for a pressure of 0.6 MPa serve as water folding fittings for the hot water supply system.
The maximum water temperature in water heaters and boilers of hot water supply systems should not exceed 75 º C, and the maximum temperature at the points of water intake should not exceed 60 º C.
Perhaps everyone knows that the huge cooling tower boilers and the striped pipes emitting smoke, which are visible from anywhere in the city, belong to the thermal power plant. Moreover, many people know that these colossus provide our homes with light, heating and hot water. But what exactly is the process of generating heat and how cooling towers are involved in it is a rather confusing question.
The entire process of CHP operation begins with water preparation. Since it is used here as the main coolant, before entering the steam boiler, where the main metamorphoses will take place with it, it requires preliminary purification. To prevent scale on the walls of the boilers, the water is first softened - its hardness sometimes needs to be reduced by 4000 times, it also needs to be rid of various impurities and suspensions.
As a fuel for heating boilers with water at various power plants, as a rule, gas, coal or peat are used. The combustion of these materials releases thermal energy, which is used at the station to operate the entire power unit. Coal is ground before use, and the incoming gas is purified from mechanical impurities, hydrogen sulfide and carbon dioxide.
A huge steam boiler in the engine room - the height of a 9-storey building is not the limit - can be called the heart of the CHP. It is powered by prepared fuel, while releasing a huge amount of energy. Under its power, the water in the boiler turns into steam with an outlet temperature of almost 600 degrees. Under the pressure of this steam, the blades of the generator rotate, as a result of which electricity is created.
The CHPP also generates thermal energy intended for heating and hot water supply of the region and the city. To do this, there are selections on the turbine that remove part of the heated steam, while it has not yet reached the condenser. The removed steam is transferred to the network heater, which acts as a heat exchanger.
Once in the pipes of network heaters, the water is heated and transferred through underground pipelines further to the heating network due to pumps that drive water through the pipes. Heating networks, as a rule, carry water of 70-150 degrees - it all depends on the temperature outside: the lower the degree outside, the hotter the coolant.
The transfer point for the coolant becomes the central heating point (CTP). It serves at once the whole system of buildings, the enterprise or microdistrict. This is a kind of intermediary between the object that creates heat and the direct consumer. If the water in the boiler room is heated due to the combustion of fuel, then the CHP works with an already heated coolant.
hot water recipeThe supply of the coolant ends at the entrance to the central heating station or ITP (individual TP) - for example, the coolant is transferred for further actions to the HOA or another management company. It is in the heating point that the hot water that we are used to dealing with is created - the water coming here from the CHP heats the clean cold water from the water intakes in the heat exchanger and turns it into the very hot that flows in our taps.
Heating the building and the room, this water gradually cools down, its temperature drops to 40-70 degrees. Part of this water is mixed with the heat carrier and supplied to our hot water taps. The road of the other part - again to the station, here the cooled water will be warmed by network heat exchangers.
The majestic and massive towers, called cooling towers, are not the reactors and centers of events at the CHP plant and actually play a supporting role. Surprisingly, they are used in thermal power plants to cool water. But why let the water that is constantly heated cool down?
Cooling towers use the second part of the “return”, which has passed through a heating-cooling cycle. But its temperature is still quite high: 50 degrees for further use is too high. The water that has been in the cooling towers is used to cool the condensers of steam turbines. This is necessary so that the steam that has passed through the steam turbine can get into the condenser and condense on the cold pipes inside it. These pipes are just cooled by water that has passed through the cooling tower, the temperature of which is now about 20 degrees. If they are not cooled, then there will be no steam flow through the turbine, then it will not be able to work. The condenser will again turn the steam into water, which will be recycled.
What needs to be done so that hot water flows immediately after opening the tap?
Depending on the method of heating water hot water supply systems (DHW) for a private country house are divided into:
As an instantaneous water heater, you can use:
Flow water heater starts to heat the water at the moment the water is being parsed when the hot water faucet is opened.
All the energy spent on heating is transferred from the heater to the water almost instantly, for a very short time of movement of water through the heater. In order to obtain water of the required temperature in a short period of time, the design of an instantaneous water heater provides for limiting the flow rate of water. The water temperature at the outlet of the instantaneous heater is very dependent on the water flow — the amount of hot water flowing from the faucet.
For a normal supply of hot water to only one horn in the shower, the capacity of the instantaneous water heater must be at least 10 kW. You can fill the bathroom in a reasonable time from a heater with a capacity of more than 18 kW. And if, when filling the bath or operating the shower, you also open the hot water tap in the kitchen, then for comfortable use of hot water, you will need an instantaneous heater power of at least 28 kW.
For heating an economy class house, a boiler of lower power is usually sufficient. That's why, the power of the double-circuit boiler is chosen based on hot water demand.
The DHW scheme with an instantaneous water heater cannot provide comfortable and economical use of hot water in the house for the following reasons:
The temperature and pressure of water in the pipes are very dependent on the amount of water flow. For this reason when another tap is opened, the water temperature and pressure in the DHW system change very much. It is not very comfortable to use water even in two places at the same time.
Ultimately, the use of an instantaneous water heater in the DHW system leads to an unreasonable increase in water consumption and volume of sewage, to an increase in energy consumption for heating, as well as to insufficiently comfortable use of hot water in the house.
A DHW system with an instantaneous water heater is used, despite its shortcomings, due to relatively low cost and small size of equipment.
The system works better if install a separate individual instantaneous water heater near each point of water analysis.
In this case, it is convenient to install electric flow heaters. However, such heaters during the analysis of water at the same time in several places can consume significant power from the mains (up to 20 - 30 kW). Usually, the power grid of a private house is not designed for this, and the cost of electricity is high.
The main parameter for choosing an instantaneous water heater is the amount of water flow that it can heat.
For example.
Three points of analysis are connected to one instantaneous water heater - a sink in the kitchen, a washbasin and a bath (shower). To fill only the bath, you must select a heater that is capable of delivering at least 9 l/min. water with a temperature of 55 about C. Such a water heater will also ensure the use of hot water simultaneously from two taps - in the sink and washbasin.
Using hot water at the same time in the shower and washbasin will be comfortable if the heater performance is already at least 9 l/min+4,2 l/min=13,2 l/min
Manufacturers in the technical specifications usually indicate maximum performance instantaneous water heater, based on water heating for a certain temperature difference, dT, e.g. 25 about C, 35 about C or 45 about C. This means that if the temperature of the water in the water supply is +10 about C, then at maximum performance, water with a temperature of +35 about C, 45 about C or +55 about C.
Be careful. Some sellers in advertising indicate the maximum performance of the device, but "forget" to write for what temperature difference it is determined. You can buy a geyser with a capacity of 10 l/min., but it turns out that at this flow rate it will only heat the water by 25 about C., i.e. up to 35 about C. Using hot water with such a column may not be very comfortable.
Suitable for our example geyser or double-circuit boiler with a maximum capacity of at least 13.2 l/min at d T=45 about C. The power of the gas apparatus with these hot water parameters will be about 32 kW.
When choosing an instantaneous water heater, pay attention to one more parameter - minimum performance, consumption l/min at which the heating is turned on.
If the water flow in the pipe is less than the value specified in the technical characteristics of the device, the water heater will not turn on. For this reason, often use more water than is necessary. Try to choose a device with the lowest possible minimum performance, for example, no more than 1.1 l/min.
Electric instantaneous water heaters designed for domestic use have a maximum heater power of about 5.5 - 6.5 kW. At maximum performance 3.1 - 3.7 l/min heat water by d T=25 about C. One such water heater is installed to service one water point - a shower, a washbasin or a sink.
A storage water heater (boiler) is a heat-insulated metal tank of a rather large volume.
In the lower part of the water heater tank, two heaters are most often built in at once - an electric heating element and a tubular heat exchanger connected to a heating boiler (). The water in the tank is heated most of the time by the boiler.
The electric heater is switched on as needed, during the shutdown of the boiler. Such a boiler is often called indirect heating boiler.
Hot water in an indirect heating boiler is consumed from the top of the tank. In its place, cold water from the water supply immediately enters the lower part of the tank, is heated by a heat exchanger and rises.
In the European Union, hot water systems in new homes are required to be equipped with a solar heater - a collector. To connect the solar collector another heat exchanger is installed in the lower part of the indirect heating boiler.
Recently the hot water system with a layered heating boiler is gaining popularity, the water in which is heated by an instantaneous water heater. In such a boiler there is no heat exchanger, which reduces its cost.
Hot water is drawn from the top of the tank. In its place, cold water from the water supply immediately flows into the lower part of the tank. The pump pumps water from the tank through the flow heater, and is supplied immediately to the upper part of the tank. Thereby, hot water at the consumer appears very quickly- no need to wait until almost the entire volume of water warms up, as happens in an indirect heating boiler.
Rapid heating of the top layer of water, allows you to install a smaller boiler in the house, as well as reduce the power of the instantaneous heater, without sacrificing comfort.
The Galmet SG (S) Fusion 100 L layered heating boiler is connected to the DHW circuit of a double-circuit boiler or to a geyser. The boiler has a built-in three-speed circulation pump. Boiler height 90 cm, diameter 60 cm. Manufacturers produce double-circuit boilers with a built-in or remote layered heating boiler. As a result,the cost and dimensions of the equipment of the DHW system are somewhat less,than with an indirect heating boiler.
The water in the boiler is heated in advance, whether it is spent or not. The supply of hot water in the tank allows you to use hot water in the house for several hours.
Due to this, water heating in the tank can be done for quite a long time, gradually accumulating thermal energy in hot water. Hence another name for the boiler - accumulative water heater.
Long duration of water heating allows use a heater of relatively low power.
Storage boilers, in which the water is heated by a gas burner, are less popular in domestic hot water systems. The device in the house of heating and hot water systems with two gas appliances - a gas boiler and a gas boiler, turns out to be much more expensive.
Accumulative gas water heater - boiler It can be advantageous to install gas boilers in apartments with central heating or in private houses with heating by a solid fuel boiler and heating water in the hot water system with liquefied gas.
Gas water heaters, as well as boilers, are produced with an open combustion chamber and with a closed one, with forced removal of flue gases and with natural draft in the chimney.
On sale there are storage gas boilers that does not require connection to the chimney. (Household gas stoves also work without a chimney.) The power of gas burners of such devices is small.
Gas boilers up to 100 liters are designed for wall mounting. Large volume water heaters are installed on the floor.
Used in water heaters different ways to ignite gas- with an on-duty wick, battery-powered electronic or hydrodynamic ignition.
In devices with standby wick a small flame burns constantly, which is first ignited by hand. Some amount of gas burns uselessly in this torch.
Electronic ignition Runs on mains power or batteries.
Hydrodynamic ignition It is started from the rotation of the impeller, which is driven by the flow of water when the tap is opened.
The larger the volume of the storage water heater, the higher the comfort of using hot water in the house. But on the other hand, the larger the boiler, the more expensive it is, the higher the cost of its repair and maintenance, the more space it takes.
The size of the boiler is chosen based on the following considerations.
Increased comfort will be provided by a boiler, the volume of which is selected at the rate of 30 - 60 liters per user of water.
A high level of comfort will be provided by a water heater with a volume of 60-100 liters per person living in the house.
To fill the bath, you need to use almost all the water from a boiler with a volume of 80 - 100 liters.
When choosing a boiler, it is necessary to pay attention to the power of the heating element that is installed in it. For example, to heat 100 liters of water to a temperature of 55 about C in 15 minutes, a heater (heat exchanger for the boiler, built-in gas burner or heating element) with a capacity of about 20 kW.
Under real operating conditions, the temperature of the water in the boiler is equal to the temperature of the water in the water supply only when the heating is turned on for the first time. In the future, in the boiler there is almost always water already heated to a certain temperature. To heat water to the required temperature in a reasonable time, heating devices of lower power are used.
But still, it is better to check how long it will take to heat the water in the boiler. This can be done using the formula:
t = m cw (t2 – t1)/Q, wherein:
t– water heating time, seconds ( With);
m- the mass of water in the boiler, kg (the mass of water in kilograms is equal to the volume of the boiler in liters);
cw- specific heat capacity of water, equal to 4.2 kJ/(kg K);
t2- the temperature to which the water must be heated;
t1– initial water temperature in the boiler;
Q– boiler power, kW.
Example:
Water heating time by a boiler with a capacity of 15 kW in a 200-liter boiler from a temperature of 10 °C(we assume that the water entering the boiler has this temperature) up to 50 °C will be:
200 x 4.2 x (50 – 10)/15 = 2240 With, that is, about 37 min.
The use of a storage water heater in the DHW system allows you to organize the recirculation of hot water in pipelines. All hot water taps are connected to a ring pipeline through which hot water is constantly circulating.
The length of the pipe section from each point of hot water consumption to the ring pipeline should not exceed 2 meters.
The circulation pump of the DHW hot water recirculation system is small in size and has low power Recirculation of water in the DHW system is provided by a circulation pump. The power of the pump is small, a few tens of watts.
DHW pumps, unlike heating pumps, must have a maximum operating pressure of at least 10 bar. Heating pumps are often designed for a maximum pressure of no more than 6 bar. Another difference is that the DHW pump must have a hygiene certificate that allows it to be used in drinking water systems.
Water in DHW systems is constantly updated and the oxygen content in it remains high enough. Corrosive activity of hot water is high. In addition, hot water must comply with sanitary requirements for drinking water. Therefore, for the manufacture of DHW pumps, corrosion-resistant non-ferrous metals or stainless steel are used. For these reasons, DHW circulation pumps are noticeably more expensive than those for heating systems.
In some designs of DHW pipelines, it is possible to create a natural recirculation of water, without a pump.
As a result of the circulation of water in the DHW system hot water is supplied to the points of selection constantly.
In a DHW system with a storage heater and water recirculation, the water supply mode is more stable:
The recirculation circuit allows not only to increase the comfort of water supply at remote points of the house, but also gives the ability to connect to it the contours of underfloor heating in separate rooms. For example, in the bathroom, a water-heated floor will be comfortable all year round.
A DHW system with water recirculation constantly consumes energy for the operation of the circulation pump, as well as to compensate for heat losses in the boiler itself and in pipes with circulating water. To reduce energy consumption, it is recommended to install a circulation pump with a built-in programmable timer that turns off water circulation during hours when it is not needed. The boiler and hot water pipes are insulated.
As you know, a double-circuit gas boiler can provide a house with hot water and be a source of heat in the heating system. Preparation of hot water is carried out in the flow heat exchanger of the boiler. Read about the general disadvantages of a DHW system with a flow heater at the beginning of this article. But gas appliances with a flow heater have another problem - this is the difficulty of choosing the maximum power of a double-circuit boiler or a hot water geyser.
Most often it turns out that the required power of the boiler for preparing hot water is much greater than the power needed to heat all the rooms in the house.
As mentioned in the article above, in order to obtain hot water of the required temperature and its maximum consumption, double-circuit gas boilers and hot water geysers have a sufficiently large maximum power, about 24 kW . or more. Boilers and columns are equipped with automation, which can reduce their power to a minimum, equal to approximately 30% of the maximum, by modulating the burner flame. The minimum power of a double-circuit gas boiler or column is usually about 8 kW. or more. This is the minimum power of the boiler, both in DHW and heating mode.
The gas burner of a double-circuit boiler or column, due to design features, cannot work stably with a power less than the minimum (less than 8 kW.). At the same time, in order to work with the heating system of a private house or autonomous heating of an apartment, the boiler in heating mode must very often give out a power of less than 8 kW.
For example, power 8 kW. enough to provide heat to the premises of a house or apartment with an area of 80 - 110 m 2, and in the coldest five days of the heating season. During warmer periods, the performance of the boiler should be significantly less.
Due to the fact that the boiler cannot work with a power below the minimum, there are problems with the adaptation (coordination) of the double-circuit boiler and the heating system.
In small facilities with low heat consumption for heating, the boiler produces more heat than the heating system can take. As a result of inconsistency between the parameters of the boiler and the system, the double-circuit boiler starts to operate in a pulsed mode, "clock"- as people say.
Work in the "clocking" mode significantly reduces the service life of boiler parts, significantly reduces efficiency.
Diagram of heating tap water by a double-circuit gas boiler or water heater depending on temperature ( T about C) and consumption ( Q l/min) hot water. The thick line shows the borders of the Working area. Gray zone, pos.1 - clock zone boiler or column (switching between ON/OFF). For normal water heating by a boiler or a column, on the diagram, the point of intersection of the temperature and hot water flow lines (working point) must always be inside the working zone, the boundaries of which are shown on the diagram with a thick line. If the hot water consumption mode is selected so that the operating point will be in the gray zone, pos. 1 on the diagram, then the boiler, the column will clock. In this zone, with a small flow of water, the power of the boiler, column turns out to be excessive, the boiler, the column turns off from overheating, and then turns on again. From the tap comes either hot or cold water.
Double-circuit gas boilers, when operating at maximum power, have an efficiency of more than 93%, and less than 80% when operating at minimum power. Imagine how the efficiency will decrease even more if such a boiler has to operate in a pulsed mode, with constant re-ignition of the gas burner.
Please note that a double-circuit boiler operates at minimum power most of the time during the year. At least 1/4 of the consumed gas will literally fly uselessly into the pipe. Add to this the cost of replacing prematurely worn parts of the boiler. This will be a retribution for installing cheap equipment for heating and hot water in the house.
If the power of a double-circuit gas boiler is more than 20 kW., selected based on the heating of the maximum required hot water flow, then the boiler cannot provide economical and comfortable operation in the mode of low heating power and when heating water with a small flow. The same can be said about the operation of the hot water column.
Most often, in the house there is no need to prepare large streams of hot water. For many people, it is much more important to provide comfortable and economical use of hot water at a low consumption.
For such economical hosts, many manufacturers produce double-circuit gas boilers and columns with a maximum power of about 12 kW. and the minimum is less than 4 kW. Such boilers, columns will provide more economical and comfortable heating and use of hot water in an amount sufficient for taking a shower or washing dishes.
Before buying a double-circuit boiler or column, the owners need to decide which mode of hot water consumption is more profitable and comfortable - with a large flow of water or with a small one. Based on this decision, choose the power of the boiler or column. If you want both, then you will have to choose a hot water system with a boiler.
For lovers of the shower, for preparing hot water and heating houses and apartments with a heated area of up to 140 m 2, with one bathroom capacity 12 kW. They are best suited to the needs of heating and hot water systems of small private houses and apartments.
For those who like to take a bath, as well as for houses and apartments of large sizes, with an area of more than 140 m 2, I strongly advise you to use a single-circuit boiler.
Many manufacturers of heating equipment produce special kits, a boiler plus a built-in or remote boiler, just for such cases. Such a set of equipment will cost more, but will provide an increased service life of the equipment, gas savings and more comfortable use of hot water.
In Western Europe and in the world, various ways to save energy when operating a private house are popular.
Hot water from the house after use flows into the sewer and carries away with it a significant part of the thermal energy that was spent on its heating.
Scheme for the recovery of thermal energy from sewage effluents to the DHW system To reduce energy losses in the house, a heat recovery (return) scheme is used from sewer drains to the hot water supply system of a private house.
Cold water passes through a heat exchanger before entering the DHW boiler. Effluent from sanitary appliances is sent to the heat exchanger.
In the heat exchanger, two streams, cold water from the mains and hot water from the drains, meet but do not mix. Part of the heat from hot water is transferred to cold water. Preheated water enters the DHW boiler.
In the diagram shown in the figure, only those sanitary appliances that work with a hot water flow are directed to the heat exchanger. It is advantageous to use such a recovery scheme for any method of water heating - both with a boiler and with a flow heater.
To return heat from the drains of sanitary appliances, which first accumulate hot water and then drain it into the sewer (bath, pool, washing machine and dishwasher), a more complex scheme is used with water circulation between the boiler and the heat exchanger during the emptying of these devices.
For houses and apartments with permanent residence, I highly recommend using DHW system with a stratified heating boiler and a double-circuit boiler, or with an indirect heating boiler and single boiler. The volume of the boiler is not less than 100 liters. The system will provide good comfort of using hot water, economical consumption of gas and water, as well as a smaller amount of wastewater to the sewer. The only disadvantage of such a system is the higher cost of equipment.
With a limited construction budget in small country houses for seasonal living you can install a DHW system with a flow heater.
It is advisable to use a hot water supply scheme with a flow heater in houses with a kitchen and one bathroom, where the heating source and hot water taps are located compactly, at a short distance from each other. It is recommended to connect no more than three water taps to one instantaneous water heater.
The cost of such a system is relatively low. and the shortcomings of operation in this case are less pronounced. A double-circuit gas boiler or gas water heater takes up little space. Almost all the necessary equipment is mounted in the body of the apparatus. For installation of a boiler with a capacity of up to 30 kW or geyser does not require a separate room.
For the preparation of hot water and heating houses and apartments with a heated area up to 140 m 2, with one shower in the bathroom, I recommend installing double-circuit gas boilers with a maximum capacity 12 kW.
In a hot water system with a geyser or a double-circuit boiler the stability of the water supply mode will increase significantly if the scheme install a buffer tank between the heater and the water taps- a conventional storage electric water heater. It is especially recommended to install such a buffer storage electric water heater near disassembly points remote from the gas appliance.
Read more: In a buffer tank scheme, hot water from a geyser or a double-circuit boiler first enters the tank of an electric boiler - water heater. Thus, the tank always contains a supply of hot water. The electric heater in the tank only compensates for heat losses and maintains the required temperature of hot water during the period when there is no water draw. An electric water heater with a tank of small capacity is enough - even 30 liters, and using hot water will become much more comfortable.
Domestic hot water system with instantaneous water heater and built into the boiler or a remote boiler of layered heating will be somewhat more expensive. But here it will not be necessary to spend expensive electricity to maintain the temperature of the water, and the comfort of using water will be the same as with an indirect heating boiler.
In houses with an extensive DHW networkimplement a scheme with a storage water heater (boiler) and water recirculation. Only such a scheme will provide the necessary comfort and economical operation of the DHW system. True, the initial costs for its creation are the largest.
It is recommended to buy boilers that are sold complete with a boiler. In this case, the parameters of the boiler and boiler are already correctly selected by the manufacturer, and most of the additional equipment is built into the boiler body.
If the heating in the house is carried out by a solid fuel boiler, then it is advantageous to install, to which and connect the DHW system with water circulation.
Otherwise, for heating water in the house, attached to a solid fuel boilerindirect heating boiler, additionally equipped with an electric heater.
It is advantageous to use an electric hot water boiler in a house with a solid fuel boiler Often, only electricity is used to heat water in a house with a solid fuel boiler. For hot water in the house, near the points of water analysis, a storage electric boiler is installed - a water heater. The hot water circulation system is not made in this embodiment. Near remote points of water analysis, it is more profitable to install your own storage heater. In this case, electricity for heating water is spent more economically.
When water is heated above 54 about C hardness salts are released from the water. To reduce scale formation If possible, heat the water to a temperature lower than indicated.
Instantaneous water heaters are especially sensitive to scale formation. If the water is hard, contains more than 140 mg CaCO 3 in 1 liter, then the use of instantaneous water heaters for heating water, including those with layered heating boilers, is not recommended. Even small deposits of scale clog the channels in the instantaneous heater, which leads to a cessation of the flow of water through it.
It is recommended to supply water to the instantaneous water heater through an anti-scale filter, which reduces water hardness. The filter has a replaceable cartridge that will have to be changed regularly.
For heating hard water, it is better to choose a DHW storage system with an indirect heating boiler. Salt deposits on the heating element of the boiler do not interfere with the flow of water, but only reduce the performance of the boiler. The boiler is easier to clean from scale.
It should be remembered that prolonged heating of water to a temperature of less than 60 ° C can lead to the appearance of Legionella bacteria harmful to human health in a storage tank (boiler) with hot water. Recommended periodically perform thermal disinfection of the DHW system, raising the temperature of the water to 70 ° C for some time.
When supplying the house with main gas, hot water supply can be realized using a gas double-circuit boiler. A double-circuit boiler is called a boiler that can heat water (or a special liquid) for heating a house, as well as heat water used for domestic needs.
The preparation of hot water in a double-circuit boiler can be carried out using a secondary heat exchanger, a built-in boiler, as well as a bithermic heat exchanger. In the first and second cases, the DHW circuit water receives heat from the liquid heated by the burner flame in the primary heat exchanger, in the third case, the heat carrier and water for the DHW circuit are heated in one heat exchanger located above the burner.
A modern double-circuit boiler can operate in two modes: for heating and for hot water supply (during the cold season), as well as only for heating domestic water in summer.
In this case, an instantaneous water heater is installed, which provides hot water to the house. Such water heaters can be of several types:
The scheme of their work is that immediately after the supply of water, its heating begins, this happens very quickly. In order to obtain high temperature water in a short time, it is necessary to limit the flow of water. The outlet water temperature will directly depend on the pressure of the water supply.
Instantaneous water heater device.
In order to be able to provide one hot water intake point with high quality, the power of such equipment must be sufficiently high. For example, 10 kW is enough to take a shower, and at least 18 kW is needed to fill a bath. If you plan that the hot water supply system will simultaneously provide several points, then you should take a device with a power of 28 kW or more.
To provide a small house, when hot water is taken from a double-circuit boiler, its power can be taken even less. It all depends on how much water you need, and knowing this value, you can correctly calculate the power of the equipment.
Disadvantages of a tankless water heater system:
All this increases the consumption of water, electricity and the load on the sewer.
Despite the presence of disadvantages, such a scheme is quite popular due to the low cost of equipment. In addition, it has a small size, which simplifies its installation. To make it comfortable to use this water heating scheme, you can do the following: put heaters near each intake point. However, if you turn them all on at the same time, then the load on the electrical network of the cottage will be very high, about 30-35 kW, which can disable it. Therefore, it is advisable to consider other types of hot water systems.
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The device of the hot water supply system in stalinkas and early Khrushchevs is no different from the distribution of cold water. The only bottling ends with dead-end risers, from which the apartment wiring departs. In the elevator unit, the filling branches into two tie-ins - into the supply and return threads.
Schematic diagram of the elevator unit and the DHW system without recirculation
Switching DHW from supply to return is carried out manually in accordance with the heating temperature schedule:
Hot water enters the house from the supply thread. Return valve closed
The advantages of such a scheme are the low cost of implementation and extremely simple maintenance. There are also downsides.
We have already mentioned two of them:
When you drain cold water, the water meter registers the flow of hot water.
Reference: the cost of a cubic meter of hot water in mid-2017 for residents of Moscow is 163 rubles. It is estimated that during the year a family of 3-4 people drains at least 10-12 cubic meters into the sewer in anticipation of heating water.
Already high DHW tariffs will continue to rise in the near future
The heated towel rail is connected to a gap in the intra-apartment piping and heats up only when hot water is disassembled
Let's throw a handful of little things into the common treasury of the shortcomings of the solution:
Dampness and mold in the bathroom - the consequences of low temperature
When heated, a pipeline made of any material noticeably lengthens
Note: the elongation of pipes during heating in the event that they touch the ceiling reinforcement can be accompanied by rather loud sounds. In the author's memory, the friction of the riser against the reinforcement led to a comical situation: the tenants accused their neighbors in the riser of .. clandestine money printing.
How does a hot water system with recirculation differ from the one described above? It's easy to guess. In it, hot water continuously circulates through spills and (in the case of a multi-storey building) hot water risers.
As a result:
The heated towel rail in the photo is connected in parallel to the riser and remains hot around the clock
As a rule, only cold water is supplied to a private house. Its heating for household needs is carried out by a local heat source. And what can become a source of water?
The video in this article will help you learn more about the design of cottage engineering systems.
If there is a main water supply near your house, the problem is solved by concluding an agreement with the local Vodokanal. After the drafting and approval of the project, a water metering well is built, a tie-in is made into the main, and a water metering unit is installed - a water meter with a coarse filter and shut-off valves.
Water meter in the well
In order for the water supply to be uninterrupted, a storage tank is installed in the house connected to the country water supply with water supply according to the schedule. The simplest solution is to install it in the attic: water will be drawn into a container when it is supplied to the water supply system through a float valve that prevents overflow, and move by gravity to the draw-off points.
Water is supplied by gravity to the water supply from a tank installed in the attic.
Alas, it is difficult to organize water supply and heating of a wooden house in this way: for wooden beams, the weight of a storage tank of several tons will be an excessive load. In this case, you can resort to plan "B": the tank is installed in an insulated basement or underground and is equipped with a pumping station with a hydraulic accumulator.
Water supply from a tank in the basement with water supply from a pumping station
How to implement water supply from a well or well?
Water supply from a well with a submersible pump
Useful: if the distance from the ground level to the water intake level is less than 8 meters, the pump can be superficial. In this case, a non-return valve is placed on its suction pipe.
Autonomous water supply scheme with a surface pump
In houses with central heating or apartments, it is advantageous to install gas boilers. Under these conditions, they provide savings, at the same level of performance. There are two types of gas boilers - with an open combustion chamber and with a closed one. This allows you to use them in an apartment without the use of additional communications, since the power is comparable to the power of a gas stove. And it does not require an additional chimney device.
As in the case, gas ignition is provided by a pilot wick that burns all the time and burns the gas uselessly, by electronic ignition using batteries, or by hydrodynamic ignition. It works when you open a cold water tap. The current turns a small turbine that ignites the gas in a burner.
Now the hot water supply system of a private house, equipped with a layer-by-layer heating boiler, is very popular. The water in such a device is heated using a flow boiler of a double-circuit boiler. Such a heater is not equipped with a heat exchanger, due to which its cost is significantly reduced.
Heated water comes from the top of the tank. Instead, cold tap water immediately begins to flow into the lower part. With the help of a pump, water from the tank passes through the flow heater, then enters the upper part of the tank. Thanks to this, the consumer instantly receives hot water, while there is no need to wait until the entire volume of water is heated, as is the case if you use an indirect heating boiler.
Due to the fact that the top layer of water warms up quickly enough, you can install a more compact boiler in a private house and reduce the power of the instantaneous water heater.
There are double-circuit boilers equipped with a built-in heater, or remote layer-by-layer heating. Thus, this equipment of the DHW system of a private house is less expensive and compact in size, unlike indirect heating boilers.
The water in the device is heated in advance, even if you do not consume it. The amount of heated water is enough for several hours of consumption.
Due to these properties, the water in the tank heats up for a long time, while the thermal energy in the hot water will constantly accumulate. Therefore, such a heater is also called a storage water heater.
Due to the long duration of water heating, you can give preference to a relatively low power heater.
How to choose a storage gas water heater for hot water supply of a private house
A storage boiler, the water in which is heated by a gas burner, is not so popular among domestic hot water systems. The use of two gas appliances - a gas boiler and a gas boiler at the same time is quite expensive.
Gas boilers are convenient to use in apartments with central heating, they are also often used in private houses with a solid fuel boiler, where hot water systems with liquefied gas are used to heat water.
Gas heaters are equipped with open and closed combustion chambers, with forced flue gas removal and natural draft in the chimney.
The market offers models of storage gas boilers for private houses that do not need to be connected to a chimney. Such devices are characterized by a small power of gas burners.
A gas boiler, the volume of which does not exceed 100 liters, is mounted on the wall, and larger heaters are installed on the floor.
Water heaters use various methods of igniting gas - for this purpose they use a standby wick, electronic battery-powered or hydrodynamic ignition.
In the device, equipped with a standby wick, a small light burns, which is first lit manually.
Electronic ignition is connected to the mains or runs on batteries or accumulators.
The hydrodynamic ignition is activated by the rotation of the impeller, which in turn is activated by the flow of water.
The comfort of using hot water in a private house directly depends on the volume of the storage heater. But the larger the boiler, the higher its cost and the more expensive the cost of its maintenance and repair work.
How to determine what size boiler for a private house to choose:
the volume of the boiler, which will provide minimal comfort, is calculated based on the consumption of 20 to 30 liters of hot water per person;
greater comfort can be provided by the hot water supply device of a private house, the volume of which is from 30 to 60 liters per user;
for a high level of comfort, a heater is chosen, the volume of which is from 60 to 100 liters for each person living in a private house;
in order to fill the bath, you need about 100 liters of hot water.
When choosing a boiler, pay special attention to how powerful the heating element is. For example, to heat one hundred liters of water to +55 ° C for a quarter of an hour, the boiler must be equipped with a heater (gas burner, etc.).
which has a power of 20 kW.
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In a private house for hot water supply, it is necessary to use a system with a storage boiler of layered or boiler heating of at least 100 liters of volume. Such a system guarantees good comfort in the use of hot water, economical water consumption and a small amount of outlet to the sewer. One disadvantage is the high cost.
With a small budget, an instantaneous water heater is installed in suburban buildings for seasonal living. This scheme is best used in houses with one bathroom and kitchen, where the heat source and water take-off point are made compact in size. It is advisable to connect no more than three taps to one heater.
Heating and hot water supply has a low cost, and the negative factors are not too pronounced. A gas boiler, consisting of two circuits, takes up less space. All equipment is installed inside the case. If the boiler power is less than 30 kilowatts, then a separate room is not required. In a hot water system, the stability of the supply is increased if a reserve tank is installed between the points of analysis and the heater in the form of a simple storage heater.
In a scheme with such a tank, water from the boiler enters the heater tank. Therefore, there is always a reserve of hot water. The heater only compensates for heat loss and maintains the temperature of the water when there is no analysis.
A hot water system with a flow heater and a layered heating boiler will cost more. But at the same time, it will not be necessary to consume electrical energy to heat water, and comfort will be like with an indirect heating boiler.
With an extensive network, it is advisable to organize the calculation of hot water supply with a storage boiler, as well as water circulation. Such a scheme guarantees the necessary comfort and economical operation of the system. However, the initial cost of installing such a system is significant.
It is advisable to purchase boilers complete with a boiler. At the same time, the characteristics of the equipment are selected in advance by the manufacturer, and the main part of the equipment is built into the boiler itself. If heating is carried out with solid fuel, then it is better to mount a reserve tank that will store heat. The entire system with water circulation is connected to it. Otherwise, to heat water, an indirect heating boiler equipped with an electric heater is connected to the boiler.
Often only electricity is used to heat water. Therefore, a storage heater is placed near the parsing sites. Hot water circulation in this case is not performed. It is more profitable to install an individual heater near points remote at a great distance. At the same time, electrical energy will be spent more economically.
When water is heated to more than 54 degrees, hard salts are released from the water. To reduce the formation of scale, it is better not to heat the water above the specified temperature. Flow heaters are sensitive to scale. If the water is too hard, the use of flow heaters is impractical. Even a small amount of scale will clog the channels in the heater and stop the flow of water.
It is advisable to supply water to a flow-type heater through a special filter that reduces water hardness. It comes with a replaceable cartridge. To heat hard water, it is better to use a storage system with indirect heating. At the same time, salt deposits will not interfere with the pressure of water, but will only reduce its effectiveness. The boiler will be easier to clean from salts.
You should be aware that prolonged heating of water leads to the appearance of harmful bacteria in the tank. Therefore, it is recommended to timely disinfect the system by thermal heating, increasing the temperature to 70 degrees.
When choosing a boiler, it is necessary to pay attention to the power of the heating element that is installed in it. For example, in order to heat 100 liters of water to a temperature of 55 ° C in 15 minutes, a heater (heat exchanger for the boiler, built-in gas burner or heating element) with a power of about 20 kW must be installed in the boiler
Under real operating conditions, the temperature of the water in the boiler is equal to the temperature of the water in the water supply only when the heating is turned on for the first time. In the future, in the boiler there is almost always water already heated to a certain temperature. To heat water to the required temperature in a reasonable time, heating devices of lower power are used.
But still, it is better to check how long it will take to heat the water in the boiler. This can be done using the formula:
t = m cw (t2 – t1)/Q, wherein: t– water heating time, seconds ( With);m- the mass of water in the boiler, kg (the mass of water in kilograms is equal to the volume of the boiler in liters); cw- specific heat capacity of water, equal to 4.2 kJ/(kg K);t2- the temperature to which the water must be heated; t1– initial water temperature in the boiler; Q– boiler power, kW.
Example:
Water heating time by a boiler with a capacity of 15 kW in a 200-liter boiler from a temperature of 10 °C(we assume that the water entering the boiler has this temperature) up to 50 °C will be:
200 x 4.2 x (50 – 10)/15 = 2240 With, that is, about 37 min.
The use of a storage water heater in the DHW system allows you to organize the circulation of hot water in pipelines. All hot water taps are connected to a ring pipeline through which hot water is constantly circulating.
The length of the pipe section from each point of hot water consumption to the ring pipeline should not exceed 2 meters.
The circulation pump of the DHW system is small in size and has low power
The circulation pump provides water circulation in the DHW system. The power of the pump is small, a few tens of watts.
In some designs of DHW pipelines, it is possible to create a natural circulation of water, without a pump.
As a result of the circulation of water in the DHW system hot water is supplied to the points of selection constantly.
In a DHW system with a storage heater and water circulation, the water supply mode is more stable:
The recirculation circuit allows not only to increase the comfort of water supply in remote points of the house, but also makes it possible to connect underfloor heating circuits to it in separate rooms. For example, in the bathroom, a water-heated floor will be comfortable all year round.
A DHW system with water circulation constantly consumes energy for the operation of the circulation pump, as well as to compensate for heat losses in the boiler itself and in pipes with circulating water. To reduce energy consumption, it is recommended to install a circulation pump with a built-in programmable timer that turns off water circulation during hours when it is not needed. The boiler and hot water pipes are insulated.
Why combine? and hot heating in private home? First of all, because it gives significant savings on the purchase and installation of a boiler as a source of hot water - with this option, this role is played by a gas or electric boiler. In addition, such a solution gives a certain saving of space that would be occupied by the boiler in the bathroom, toilet, kitchen or service room. This is the main advantage of the combined scheme of water supply and hot heating of a private house.
At the same time, of course, such a system is not an ideal solution and has its drawbacks. These include:
Separately, it is worth focusing on the scheme of operation of the heating system in relation to the flow rate factor of the coolant (in the combined scheme, of course, water). . There are also two options for implementing the scheme:
There are also two options for implementing the scheme:
It is worth noting that since the expansion tank in this case is also a hot water storage tank in the combined scheme, additional requirements apply to its selection and installation. In particular, it must have a decent volume and be installed at such a height that the pressure of hot water in the system is sufficient for its efficient operation. The collapsible fittings of the DHW system should rise above its bottom at a height of 10-15 cm in order to eliminate the risk of scooping out the entire volume of water, which will lead to disruption of the heating system.
As an illustrative example, we will work with a gas boiler, steel panel radiators and plastic pipes. Of course, water can also be supplied to radiators through steel pipes, but this is costly and not so durable. Plastic doesn't rust, and it's pretty inexpensive. In addition, for the installation of a heating system with plastic pipes, it is not necessary to carry out lengthy welding and painting work. As a rule, even a very complex system is assembled in just 1-2 days.
plastic pipes
And for its installation, we need this.
From the tool, prepare the following:
And from consumables, in addition to the radiators themselves and plastic pipes, you will need the following:
Perhaps, in your particular case, you will need something else, but, as a rule, what is listed above is enough.
Soldering iron and scissors for plastic pipes
Consider some important installation rules.
Most likely, it will not be you who will install the boiler for hot water supply and heating, but a specialist from the gas service or service center, but still it will not be superfluous to know the following points:
After the boiler is suspended, all radiators must be attached. Here, too, there are enough nuances.
In principle, after the batteries are fixed, you can measure how many pipes you need, how long, then cut the pieces you need and solder them.
Soldering plastic pipes
Tip: do not use fittings made of bad, cheap metal to connect the pipe and the battery, they are bad because they can simply break with a more or less strong turn of the wrench, and also because in just a couple of years they will most likely have to be changed.
After the system of pipes and radiators is ready, you can connect everything to the boiler and call the wizard. He will start the water in the system, check the boiler settings and start the heating.
The larger the volume of the storage water heater, the higher the comfort of using hot water in the house. But on the other hand, the larger the boiler, the more expensive it is, the higher the cost of its repair and maintenance, the more space it takes.
The size of the boiler is chosen based on the following considerations.
Increased comfort will be provided by a boiler, the volume of which is selected at the rate of 30 - 60 liters per user of water.
A high level of comfort will be provided by a water heater with a volume of 60-100 liters per person living in the house.
To fill the bath, you need to use almost all the water from a boiler with a volume of 80 - 100 liters.
When choosing equipment for hot water supply and heating a private house, it is necessary to take into account a number of factors, namely: how much hot water is needed per day; is the site electrified; are there conditions, i.e. an open place, lit by the sun all day, for the installation of a solar collector.
When the need for hot water is constant and increased, as a rule, the owners of individual houses buying a powerful double-circuit boiler prefer to develop their own hot water system, taking into account specific conditions. There is no one size fits all solution as there are many options. The most popular hot water supply device is a system based on a single-circuit heating boiler connected to a boiler.
A boiler is a device designed to heat water and maintain it at a certain temperature; Simply put, this is a water heater with a built-in heat exchanger. Structurally, heat exchangers (these are devices in which heat is transferred from a hot carrier (liquid, gas) to a colder one) are different (shell-and-tube, sectional, etc.), however, in recent years, plate heat exchangers, which are compact, have a high coefficient of heat transfer and efficiency of 99%.
Providing a home with a hot water supply system is impossible without creating hot water recirculation circuits. As a rule, this is a pipeline in the form of a loop, which is directed from the boiler past the hot water taps and returns to the boiler. Thanks to such a system, hot water flows out of the tap after 1-2 seconds, and not after 5-25 seconds, as would happen if the tap was far away from the heat exchanger. In addition, without creating recirculation, while waiting for hot water to flow from the tap, a huge amount of it simply flows into the sewer, i.e. spent uneconomically.
Before proceeding with the choice of model, you should find out about the following indicators: a shower or bath consumes about 9 liters of hot water per minute, and a sink is about 4.2. Further calculation is simple - the indicators of all water flow points that this water heater provides are summed up and we get its power.
For example. If the water heater provides a bathroom, then it needs water for the shower and washbasin. Accordingly, its performance should be 9 + 4.2 = 13.2 l / min.
When choosing a particular model, it is necessary to look not only at performance, but also at the temperature difference. It should provide heating up to 55 degrees. This point is often hushed up by sellers, and the emphasis is on performance, so you need to learn about it separately.
In addition to the working volume, it is also necessary to know the minimum switch-on size - an indicator indicating the minimum amount of water passing through, at which the heater will turn on. It is optimal if it is only 1.1 liters.
When erecting a new building, it makes sense to immediately install a storage boiler with a capacity of over 100 liters. It will provide comfort of living without the need for alterations in the future.
If the house is used infrequently, for example, in a summer house, then it makes no sense to install a storage system, a flow heater is enough. At the same time, the compact arrangement of flow points in such buildings will provide convenience during operation.
With a large family, you can install an additional capacity in the storage water supply system. A tank of 30 liters with additional electric heating, which serves to compensate for heat loss, will allow you to compensate for fluctuations in water consumption with a large number of households.
When buying a gas boiler, preference should be given to ready-made boiler-boiler kits. Their parameters are already selected for each other, such a bundle will optimally consume heat.
With solid fuel heating at home, it makes sense to use a heat storage tank to create a secondary hot water circuit. This will significantly reduce energy costs.
At a temperature of 55 degrees and above, salts begin to actively fall out of the water. They clog the lumen of the pipes and impair the flow of water.
This is especially important for flow heaters, which heat large volumes over short pipe lengths. If the water contains more than 140 mg of impurities per liter of water, then instantaneous water heaters cannot be used - they fail too quickly and stop heating the water
As an instantaneous water heater, you can use:
Flow water heater starts to heat the water at the moment the water is being parsed when the hot water faucet is opened.
All the energy spent on heating is transferred from the heater to the water almost instantly, for a very short time of movement of water through the heater. In order to obtain water of the required temperature in a short period of time, the design of an instantaneous water heater provides for limiting the flow rate of water. The water temperature at the outlet of the instantaneous heater is very dependent on the water flow - the amount of hot water flowing from the faucet.
For a normal supply of hot water to only one horn in the shower, the capacity of the instantaneous water heater must be at least 10 kW. You can fill the bathroom in a reasonable time from a heater with a capacity of more than 18 kW. And if, when filling the bath or operating the shower, you also open the hot water tap in the kitchen, then for comfortable use of hot water, you will need an instantaneous heater power of at least 28 kW.
For heating an economy class house, a boiler of lower power is usually sufficient. That's why, the power of the double-circuit boiler is chosen based on hot water demand.
The DHW scheme with an instantaneous water heater cannot provide comfortable and economical use of hot water in the house for the following reasons:
Hot water from the tap appears with some delay. The waiting time increases as the length of the pipes from the water heater to the point of water analysis increases. Part of the water at the very beginning has to be uselessly drained into the sewer. Moreover, this is water that has already been heated, but managed to cool down in the pipes.
Ultimately, the use of an instantaneous water heater in the DHW system leads to an unreasonable increase in water consumption and the volume of sewerage, to an increase in energy consumption for heating, as well as to insufficiently comfortable use of hot water in the house.
A DHW system with an instantaneous water heater is used, despite its shortcomings, due to relatively low cost and small size of equipment.
The system works better if install a separate individual instantaneous water heater near each point of water analysis.
In this case, it is convenient to install electric flow heaters. However, such heaters during the analysis of water at the same time in several places can consume significant power from the mains (up to 20 - 30 kW). Usually, the power grid of a private house is not designed for this, and the cost of electricity is high.
Storage boiler device.
A feature of the recovery process is that it can be used with both flow-through and storage heaters.
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The use of electric water heaters is quite common in everyday life. It can be of two types: the cumulative principle or the opposite.
Accumulative - this is when water is drawn into the tank and heated to a certain temperature by an electric heater. After reaching the temperature of the set value, the heaters are periodically switched on and off to maintain this temperature.
Flow - this is when water heats up almost instantly, passing through electric heaters.
Compared to the previous system, this one has the advantage that it is not connected to the heating system.
With instantaneous electric heaters, water does not take time to heat up.
Cons of electric water heaters:
The cost of electricity consumption is much higher than the cost of gas consumption for heating water.
Electricity is quite dangerous especially when combined with water. The chance of injury from electric shock is very high compared to using gas.
Despite the advantages of a combined heating system, there are also disadvantages:
Installation of heating in the house - water supply begins with the choice of the wiring diagram for engineering systems.
Cold water is diluted according to a dead-end scheme (that is, it moves through the water supply system only when drawing water).
The wiring can be:
| Image | Description |
Tee wiring is typical for Soviet-built buildings | Tee: tapping points are connected in series to a common supply line for all. The advantage of tee wiring is a small material consumption, the disadvantage is the pressure drop in the entire water supply system when water flows through any connected device. |
Collector cabinet for water supply | Collector: each device is equipped with its own supply, starting in the collector cabinet and equipped with a shut-off valve. There is no drop in pressure, but the consumption of pipes is several times greater and, willy-nilly, it is necessary to mount them only hidden. |
In addition to dead-end wiring, DHW circuits are practiced with recirculation. The circulation pump continuously pumps water between the boiler tie-ins. This ensures an instantaneous supply of hot water to any tap and continuous heating of heated towel rails mounted in a gap.
DHW supply with recirculation from an indirect heating boiler
Like water supply, heating can be collector or sequential (tee). The first type of wiring is more often used with water-heated floors: the high hydraulic resistance of small-diameter pipes laid in a screed limits the length of one circuit to a value of 100-120 meters.
In addition, heating wiring can be:
| Image | Description |
Classic "Leningrad": batteries are connected in parallel to a single bottling | Single pipe. The so-called Leningradka is a heating filling ring with radiators connected in parallel to it. The advantage of Leningradka is absolute fault tolerance: as long as there is at least some drop at the ends of the filling, circulation in it continues. The disadvantage is a significant temperature difference between the heating devices. |
Dead-end two-pipe wiring: radiators closest to the boiler are hotter than distant ones, since most of the coolant circulates through them | Two-pipe dead-end: radiators are connected as jumpers between the supply and return bottlings; at the same time, at the moment of flow from bottling to bottling, the direction of movement of the coolant changes to the opposite. Such wiring allows you to bypass any obstacles and form several parallel branches of the heating system. However, the jumpers between fillings cause the difference between them to fall as they move away from the boiler. The result is cooling of distant heaters up to defrosting in extreme cold. The problem can be solved by balancing - by limiting the patency of the connections of the batteries closest to the boiler. |
The Tichelmann loop ensures the same temperature of the batteries without throttling the lines | Two-pipe associated (Tichelmann loop). Several small contours are formed in it with the same length and, accordingly, the same hydraulic resistance. As a result, all batteries are heated to the same temperature. |
Installation of heating and water supply in a country house includes, among other things, the installation of heating appliances. If panel radiators and convectors are mounted only in the manner provided by the manufacturer, then sectional radiators can be connected to a filling or riser according to one of three schemes.
| Image | Description |
One-way connection - for a moderate number of sections | Lateral one-way connection is effective when the length of the battery is not more than 10 sections. If it is longer, the extreme sections will be noticeably colder than those closest to the eyeliners. |
Diagonal connection to two outlets | Diagonal connection is effective for any length of the device and provides uniform heating of all sections. |
The hoses are connected only to the lower radiator manifold | The lower two-way connection is advantageous in that it guarantees circulation even when the circuit is aired (air is displaced into the upper manifold, and circulation goes through the lower one). In addition, with a lower two-way connection, the battery will never need to be flushed: all the sludge is carried away by the coolant circulating through the lower collector. |
Heating and hot water supply of a private house can use common or different heat sources. Let's start with an analysis of the economic efficiency of different methods of heating water (in other words, find out how much a kilowatt-hour of heat will cost with different methods of obtaining it).
If there is gas on your street, you can not look for other sources of heat
Hint: electric, gas and diesel boilers are often equipped with a separate heat exchanger for hot water needs (the so-called double-circuit boilers). However, absolutely any heating boiler can be used for the same purpose by connecting an indirect heating boiler to it - a heat-insulated tank, the water in which is heated by the energy of the heating system coolant.
An indirect heating boiler uses the thermal energy of the heat carrier of the heating system
Ideally, water supply and heating of a private house should not only be economical. They should also require as little attention as possible from the owner, if possible maintaining the optimum temperature of air and tap water in a fully automatic mode.
According to this parameter, heat sources are distributed in a different order:
Electric boiler: turned on and forgot
Practical conclusion: all so-called economical electric boilers and electric radiators are fiction. To get a kilowatt of heat, you need to spend a kilowatt of electricity, regardless of the principle of heating the coolant. This thesis follows directly from the law of conservation of energy.
Electrode and induction boilers have a number of advantages over heating elements, but efficiency is not among them
Diesel boiler room: a significant part of the volume of the room is occupied by fuel tanks
However: top-burning pyrolysis boilers operate on one tab for up to a day and a half due to a special fuel combustion scheme. It smolders with limited air access with afterburning of products of incomplete combustion in a separate chamber. The smoldering process, directed from top to bottom, eliminates the ignition of firewood or coal throughout the entire volume of the furnace.
Solid fuel pyrolysis boiler of upper combustion
A double-circuit gas boiler will provide the house with cheap heating and hot water
Nuance: heating automation is expensive. In Sevastopol, where the author lives, an automatic boiler with a capacity of 10 kW can be bought for 90-95 thousand rubles.
Classic wood-burning boiler in a country house
The most modern approach to solving two problems at once in one go. Double-circuit boilers are designed for heating heating and heating water in the water supply system. Each function has a separate heating circuit. Turbocharged wall-mounted boilers do not require the installation of a chimney. This device combines two at once: a gas boiler and a gas column.
Among other things, such models of boilers already have a circulation pump, which improves the circulation of water in the system, increasing the efficiency of the boiler.
We kill two birds with one stone (both heating and hot water are independent of each other). Saving space in the boiler room. Cheaper gas project. Does not require a chimney. There is a built-in circulation pump.
Flaws.
If one thing breaks, then you will be left without hot water and heating. This is perhaps the only negative, but practice shows that something breaks in such boilers very rarely.
Let's summarize.
Our choice in favor of the latest turbocharged boiler system with two circuits.
As you know, a double-circuit gas boiler can provide a house with hot water and be a source of heat in the heating system. Preparation of hot water is carried out in the flow heat exchanger of the boiler.
Most often it turns out that the required power of the boiler for preparing hot water is much greater than the power needed to heat all the rooms in the house.
To heat the required amount of water, double-circuit boilers have a sufficiently large maximum power, about 24 kW . or more. The boilers are equipped with automatic equipment, which, due to the modulation of the burner flame, can reduce the boiler power to a minimum, equal to approximately 30% of the maximum. The minimum power of a double-circuit gas boiler is usually about 8 kW. or more. This is the minimum power of the boiler, both in DHW and heating mode.
The gas burner of a double-circuit boiler, due to design features, cannot work stably with a power less than the minimum (less than 8 kW.). At the same time, in order to work with the heating system of a private house or an autonomous heating of an apartment, the boiler in heating mode must very often produce less than 8 kW.
For example, power 8 kW. enough to provide heat to the premises of a house or apartment with an area of 80 - 110 m2, and in the coldest five days of the heating season. During warmer periods, the performance of the boiler should be significantly less.
Due to the fact that the boiler cannot work with a power below the minimum, there are problems with the adaptation (coordination) of the double-circuit boiler and the heating system.
In small facilities with low heat consumption for heating, the boiler produces more heat than the heating system can take. As a result of inconsistency between the parameters of the boiler and the system, the double-circuit boiler starts to operate in a pulsed mode, "clock"- as people say.
Work in the "clocking" mode significantly reduces the service life of boiler parts, significantly reduces efficiency.
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Double-circuit gas boilers, when operating at maximum power, have an efficiency of more than 93%, and less than 80% when operating at minimum power. Imagine how the efficiency will decrease even more if such a boiler has to operate in a pulsed mode, with constant re-ignition of the gas burner.
Please note that a double-circuit boiler during the year works most of the time in heating mode, with a minimum power. At least 1/4 of the gas used for heating will literally fly out uselessly into the pipe. Add to this the cost of replacing prematurely worn parts of the boiler. This will be a retribution for installing cheap equipment for heating and hot water in the house.
When the heating system power is less than 8 kW. it is more profitable to install the boiler complete with a hot water boiler for 60 - 120 liters.
The presence of a storage boiler will allow you to install a boiler of lower maximum power, less than 9 - 11 kW. The boiler in conjunction with the boiler will operate at optimal power, both in heating and hot water mode.
Many manufacturers of heating equipment produce special kits, a boiler plus a built-in or remote boiler, just for such cases. Such a set of equipment will cost more, but will provide an increased service life of the equipment, gas savings and more comfortable use of hot water.
Consider how the heating and water supply of a private house is assembled, what is required to complete the work and what you should pay attention to. For example, we will consider a gas boiler, plastic pipelines and steel radiators.
Water can be supplied to radiators and through steel pipes, but they last less and cost more. Plastic pipes do not rust, and their price will suit a family with a small budget.
Installation and assembly of a heating system consisting of plastic pipes does not require painting and welding. Usually the whole system is assembled in a couple of days, even a complex one.
You need to prepare the following tool:
Consumables will need the following:
In each case, the materials are usually supplemented on an individual basis; shut-off valves are provided to turn off the hot water supply.
The installation of the system is usually carried out by a service specialist, but it does not hurt to get acquainted with some points:
After installing the boiler, fix the radiators:
After installing the batteries, you can measure the pipes and cut them for soldering. Cheap fittings of poor quality should not be used to connect pipes and radiators. When a large load is applied with a wrench, they often break. After assembling the system of radiators and pipes, you can connect the system to the boiler and make an application to call the master, who will check the correctness of the assembly, make settings and start the water.
Since the consumption of hot water by the residents of the house is carried out periodically, as needed, it makes no sense for the DHW recirculation pump to operate continuously. The operation of the recirculation pump for water in the mode of periodic switching on and off reduces the load both on the equipment itself and on the pipeline as a whole. There are two ways to ensure the operation of recirculation pumps in periodic mode:
The difference between such recirculation pump controls lies both in their design and in the principle of operation.
Temperature sensor control
This method of controlling the operation of the recirculation pump involves the use of a temperature sensor, the working part of which is in constant contact with the liquid transported through the pipeline. When the temperature of the water in the DHW system or in the heating system drops to a critical value, the sensor automatically turns on the recirculation pump, and when the liquid temperature rises to the required level, turns it off. The use of a temperature sensor to control the operation of the recirculation pump allows you to maintain a stable temperature of the liquid in the pipeline being serviced. When using a temperature sensor, it is also convenient that it can be adjusted to any temperature at which it will operate.
Grundfos recirculation pump with thermostat (temperature sensor)
Timer control
Household recirculation pumps can be equipped with timers that will turn the equipment on and off according to a specific schedule. The timer operation time and the duration of the equipment operation are calculated depending on the length of the pipeline and the volume of liquid in it, the calculation also takes into account heat losses in the pipes and pump performance.
Using the timer, you can increase the period between turning off the recirculation pump and then turning it on up to a week. This option is especially relevant in cases where there is no need for hot water during a certain period, respectively, it also makes no sense to turn on the pump and load it idle.
Recirculation pump with integrated timer
When using a water recirculation pump, it is also important to know how such devices are connected to heating and hot water systems. There are two main schemes for connecting a recirculation pump:. sequential (the electric pump is connected to one pipeline circuit that serves all water intake points);
The constant supply of hot water to an apartment building can be carried out by two methods using different principles of operation:
Important: the advantage of the second version of the water supply system for a residential building is the best water quality, which is regulated by GOST R 51232-98. Also, when hot water is taken from a centralized heating main, the temperature and pressure of the liquid are quite stable and do not deviate from the specified parameters: the pressure in the pipeline of the hot water supply system is maintained at the level of cold water supply, and the temperature stabilizes in the common heat generator.
Let us consider the water supply of an apartment building according to the second option in more detail, since it is this scheme that is most often used both in the city and in country houses, including country houses or garden houses.
The water meter unit, which organizes the supply of water to the house, is responsible for the operation of several functions:
The device itself consists of the following nodes:
It is also an elevator unit that performs the following functions:
The main element of the heating point is a water-jet elevator, where hot water from the pipeline scheme for supplying the working fluid in the house is mixed in the mixing chamber with the return coolant by injection through a special nozzle. Thus, the elevator allows a larger volume of coolant with a low temperature to pass through the heating circuit, and, since the injection is performed through a nozzle, the supply volume is small.
It is possible to insert adapters for connecting hot water supply between the valves at the entrance of the route and the heat point - this is the most common connection scheme. The number of tie-ins - two or four (one or two on the supply and return). Two tie-ins are typical for old houses, four adapters are practiced in new buildings.
On the cold water route, a dead-end tie-in scheme with two connections is usually used: the water metering unit is connected to the bottling, and the bottling itself is connected to the risers, through which the pipes are routed to the apartments. Water will move in such a cold water circuit only when disassembled, that is, when any mixers, taps, valves or gates are opened.
Disadvantages of this connection:
A heating station with four hot water connections in the house makes the circulation of hot water continuous, and this happens through two fillings and risers connected to each other by jumpers.
Important: if mechanical water meters are installed on the DHW tie-ins, then the water supply consumption will be taken into account without taking into account the water temperature, which is wrong, since you will have to overpay for hot water that was not in use.
Hot water supply can function in three ways:
The continuous movement of water requires a pressure drop between the start and end points of the tie-in into one circuit, and this drop is provided by flow restriction. Such a limiter is a special retaining washer - a steel pancake with a hole in the middle. Thus, the water that is transported from the inlet tie-in to the elevator encounters an obstacle in the form of a washer body, and this obstacle is adjusted by turning, which opens or closes the retaining hole.
But too much restriction of water movement in the pipeline route will disrupt the operation of the heat point, so the retaining washer should have a diameter 1 mm larger than the diameter of the heat point nozzle. This size is calculated by the representatives of the heat supplier so that the temperature on the heating return pipe of the elevator unit lies within the normative limits of the temperature chart.
These are pipes laid horizontally and carried through the basement of a residential building, which connect the risers with a heat point and a water meter. The bottling of cold water supply is done single, bottling hot water - in two copies.
The diameter of the DHW or cold water filling pipes can be 32-100 mm, and depends on the number of connected consumers. For any water supply scheme, ø 100 mm is too large, but this size is taken taking into account not only the actual condition of the route, but also taking into account the size of salt deposits and rust on the inner walls of metal pipes.
The pipe vertical riser distributes water to the apartments that are located above it. The standard scheme for such wiring includes several risers - for cold and hot water supply, sometimes - separately for heated towel rails. More wiring options:
The standard diameter of pipes for cold and hot water supply for risers is 25-40 mm. Risers for heated towel rails and idle risers are mounted from pipes ø 20 mm. Such risers provide both single-pipe and two-pipe heating systems at home.
The constant circulation of water in a closed hot water supply system is based on the principle of taking cold water from the pipeline and supplying it to the heat exchanger. After heating, the water is supplied to the distribution system around the apartment. The working fluid in the heating system and hot water for the technical needs of consumers are separated, since the coolant may have toxic inclusions to improve its heat transfer qualities. In addition, hot water pipes rust faster. Such a scheme is called closed due to the fact that the consumer uses heat, and not the coolant itself.
The main function of the piping is to distribute water to the points of water intake in the apartment. The standard diameter of the supply pipes is 15 mm, the pipe grade is DN15, the material is steel. For PVC or metal-plastic pipes, the diameter must be the same. When repairing or replacing the piping, it is not recommended to use a smaller diameter so as not to change the design pressure parameters that the hot or cold water circulation system must comply with.
To organize the correct eyeliner, tees are most often used, with a more complex wiring diagram - collectors. Collector piping requires concealed installation, so the collector should be installed when servicing a large number of rooms in the house. After 10-15 years, metal pipes are overgrown from the inside with salt mineral deposits and rust, therefore, preventive work to restore the system's performance consists in cleaning the pipes with steel wire, or replacing old pipes with new ones.
With the seeming functionality and durability of PVC or metal-plastic pipes, it is recommended to use steel products for piping - they hold water hammer and temperature changes well. Such deviations in the DHW operating mode can often be observed when the heating system is turned on or turned off in an emergency. It is necessary to lay the pipe material in the plan of the water supply scheme of a residential building even at the stage of drawing up a project and estimate.
The calculation of the amount of hot water in the system depends on technical and operational factors:
Calculation example:
These theoretical calculations work assuming average water consumption by residents.
With your own hands, you can fix the following emergencies:
Leaking valve or faucet. This happens most often due to wear of the oil seal or seal. To eliminate the malfunction, it is necessary to open the valve completely and with force so that the raised stuffing box closes the leak. This technique will help for a while, in the future the valve must be sorted out and worn parts replaced.
Noise and vibration of a valve or tap when opening in a hot water supply system (less often - cold). The cause of noise is most often wear, deformation or crushing of the gasket in the crane box of the mechanism. Noises appear if the valve does not open completely. This malfunction can cause a series of water hammers in the pipes, so its elimination is of paramount importance. In a few milliseconds, the crane box valve is able to close the valve seat in the valve or valve body, if it is not a ball valve, but a screw one. Why is the risk of water hammer higher in DHW? Because in pipes with hot water, the working pressure is greater.
How to troubleshoot:
The towel warmer does not heat up. The cause of the breakdown may be the presence of air in the water supply system with constant circulation of the coolant. Usually, air accumulates in a pipe jumper, which is mounted between adjacent risers, after an emergency or planned drain of water. The problem is eliminated by bleeding air jams. For this you need:
At the end of the heating season, the pressure difference between the pipes of the heating main may not be observed, and because of this, heated towel rails connected directly to the DHW will be cold. This is not a cause for concern - you need to bleed the air, which equalizes the pressure, and the heating will be restored.
