Hot water supply to a private home is an important engineering system, the arrangement of which always remains a pressing issue. This is a necessary condition in order to fill the house with coziness and make it comfortable for living. The installation of modern water heaters successfully solves the problems of hot water supply and heating in a private home, and for this it is no longer necessary to have powerful electrical wiring, gas or a chimney. All you need is to familiarize yourself with the operating principles of various systems, select a suitable scheme, and, if desired, you can carry out the installation yourself.
Scheme of hot water supply with instantaneous water heater
The following can be used as an instantaneous water heater:
- DHW gas water heater;
- DHW heating circuit of a double-circuit heating boiler;
- electric instantaneous water heater.
- plate heat exchanger connected to the heating circuit.
The instantaneous water heater begins to heat the water at the moment the water is drawn
when the hot water tap is opened.
All energy spent on heating passes from the heater to the water almost instantly , in a very short time of water movement through the heater. In order to obtain water at the required temperature in a short period of time, the design of an instantaneous water heater provides for limiting the speed of water flow. The water temperature at the outlet of the flow-through heater very much depends on the water flow -
the size of the stream of hot water flowing from the tap.
To properly supply hot water to only one shower head, the power of the instantaneous water heater must be at least 10 kW. You can fill a bathroom in a reasonable time using a heater with a power of more than 18 kW
.
And if, when filling the bath or running the shower, you also open the hot water tap in the kitchen, then for comfortable use of hot water you will need a flow heater power of at least 28
kW. To heat an economy class home, a lower power boiler is usually sufficient. Therefore, the power of a double-circuit boiler is chosen
based on the need for hot water.
A DHW circuit 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 very much depend on the amount of water flow. For this reason When you open another tap, the water temperature and pressure in the hot water system changes greatly.
It is very uncomfortable to use water even in two places at the same time.
- When the flow of hot water is low, the instantaneous water heater does not turn on at all and does not heat the water.
To obtain water at the required temperature, it is often necessary to use more water than necessary. - Each time the water tap is opened, the instantaneous water heater starts again. It constantly turns on and off, which reduces its service life . Each time, hot water appears with a delay, only after the heating mode has stabilized. Frequently restarting the heater reduces efficiency and increases energy consumption. Some of the water goes down the drain uselessly.
- It is impossible to recirculate water in the distribution pipes throughout the house. 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 water collection point increases.
Some of the water at the very beginning has to be drained uselessly into the sewer.
Moreover, this is water that has already been heated, but has managed to cool down in the pipes. - Scale deposits quickly accumulate
on a small surface inside the heating chamber of an instantaneous water heater. Hard water will require frequent descaling.
Ultimately, the use of an instantaneous water heater in a domestic hot water 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.
The DHW system with instantaneous water heater is used, despite its disadvantages, due to the relatively low cost and small size of the equipment
.
The system works better if a separate individual instantaneous water heater is installed near each water collection point.
In this case, it is convenient to install electric flow heaters. However, such heaters, when drawing water simultaneously in several places, can consume significant power from the electrical network (up to 20 - 30 kW). Typically, the electrical network of a private home is not designed for this, and the cost of electricity is high.
Operating principle of an autonomous water supply system
The water supply system is one of the most important elements in home improvement. The essence of its work is the automated supply of the required volume of water, for which the user now only needs to start the equipment and then simply periodically monitor it.
An autonomous network independent of the central water supply must be properly designed and calculated in order for the house to be fully provided with water according to the needs of the owners. The system must be organized so that water flows freely to all water intake points.
For normal operation, the water supply system is equipped with devices and technical devices that provide automatic or partially automatic operation.
To automate the process, a hydraulic accumulator is used. It is used as a buffer tank for storing water and as a device for maintaining stable pressure.
The membrane tank has two compartments - for air and water, they are separated by a rubber membrane. When the container is filled with water, the air chamber is compressed more and more, causing the pressure to increase.
Autonomous water supply systems consist of internal and external parts. Includes pipeline branches of the same name, laid from the source of water intake to water collection points, fittings, plumbing, pump, storage tank or hydraulic accumulator
Reacting to an increase in pressure, the electric relay turns off the pump. As soon as one of the owners opens the tap, the pressure in the system begins to drop. The relay again reacts to a decrease in pressure and turns on the pump unit to replenish the consumed water.
The use of a hydraulic accumulator in a water supply system allows not only to automate the process of water intake and ensure its supply. The service life of pumping equipment is significantly extended due to the reduction of on/off cycles.
Water supply is the life support of a home. It depends on how comfortable a person will live in his home.
To select the correct system parameters, you must:
- Formulate requirements for the intensity and regularity of water supply. It is possible that in a small country house you can get by with a system with a regular storage tank and a minimum of plumbing fixtures.
- Determine possible sources, feasibility and cost of their construction, water quality.
- Select equipment and calculate options for laying utility networks.
A well-designed system requires professional installation and the use of high-quality components.
How to choose an instantaneous water heater
The main parameter for choosing an instantaneous water heater is the amount of water flow that it can heat.
For comfortable use, it is recommended to focus on the following volumes of hot water consumption at a temperature of 55 ° C at the points of analysis:
- from the sink faucet or washbasin 4.2 l/min (0.07 l/sec);
- from the bath or shower tap 9 l/min (0.15 l/sec).
For example.
Three points of disassembly are connected to one instantaneous water heater - a sink in the kitchen, a washbasin and a bathtub (shower). To fill only the bathtub, you must select a heater that is capable of delivering at least 9 l/min. water with a temperature of 55 oC. Such a water heater will also provide the use of hot water simultaneously from two taps - in the sink and washbasin.
It will be comfortable to use hot water in the shower and washbasin at the same time if the heater capacity is no less than 9 l/min + 4.2 l/min = 13.2 l/min.
Manufacturers in the technical specifications usually indicate the maximum performance of an instantaneous water heater, based on heating water at a certain temperature difference, dT, for example, 25 °C, 35 °C or 45 °C. This means that if the water temperature in the water supply is +10 °C, then at maximum performance, water with a temperature of +35 °C, 45 °C or +55 °C will flow from the tap.
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 °C, i.e. up to 35 oC. Using hot water with such a column may not be very comfortable.
For our example, a gas water heater or a double-circuit boiler with a maximum productivity of at least 13.2 l/min at dT=45 °C is suitable. The power of the gas appliance with these hot water parameters will be about 32 kW.
When choosing an instantaneous water heater, pay attention to one more parameter - the minimum performance, the flow rate l/min at which 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, it is often necessary to use more water than necessary. Try to choose a device with the minimum minimum capacity as low as possible, for example, no more than 1.1 l/min.
Electric instantaneous water heaters intended for domestic use have a maximum heater power of about 5.5 - 6.5 kW. At a maximum productivity of 3.1 - 3.7 l/min, water is heated at dT = 25 °C. One such water heater is installed to serve one water point - a shower, washbasin or sink.
Equipment and materials
Many people wonder how to make plumbing with their own hands. This is quite within the capabilities of anyone who has a desire to understand its structure.
The selection of equipment is carried out after determining the source. To connect to the central water supply, pipes and shut-off taps are sufficient. It is advisable to install a well at the connection point, but you can do without it. This is determined by the technical conditions issued by the water utility.
In the case of an autonomous option, the water supply scheme becomes significantly more complicated. Various equipment will be required for lifting and cleaning.
Pump equipment
A submersible or surface pump is used to supply water. Surface pumps are much cheaper than submersible pumps and can be purchased immediately with a hydraulic accumulator; this installation is called a pumping station. They are easy to maintain, and the well casing can be of small diameter, sufficient for the passage of a water intake hose with a filter tip.
Pumping stations are suitable for drawing water from surface sources. They are also installed if the pressure in the central water supply is very low and does not suit the consumer.
If the depth to the surface of the water in the well (well) is more than 5 meters, then the choice clearly remains with a submersible (deep) pump.
When choosing a pump, take into account:
- height of water rise (pressure) from the depth of the pump to the highest point of water collection in the house;
- required hourly flow rate (liter/min.), taking into account the number of users;
- pump diameter, taking into account the diameter of the well casing:
- pump type: vibration, vortex, borehole, centrifugal (the last 3 pumps are a type of centrifugal).
Vibration pumps are inexpensive, but they are not recommended for use in wells, due to the vibration created in the environment; they are only suitable for wells. The most reliable choice is a vortex pump. It has the lowest requirements for water purity.
Important: in each specific case, taking into account the type of well, water purity, and lifting depth, the right choice can only be made by a specialist with experience in operating pumps in a given area.
Hydraulic accumulator
For every electric motor, the hardest moment is starting up. Increased currents by 7 times, low torque, starting under load, all this significantly reduces its service life. To prevent the pump from starting frequently, due to a glass of water, a minute of hand washing, flushing the toilet, leaks in the network and other little things, a hydraulic accumulator must be installed.
And the larger the tank volume, the better for the pump. As well as for users, in case of a power outage
Its installation is mandatory, and its good condition is very important.
The volume of the hydraulic accumulator for water supply is determined by a special calculation. Simplified, you can select by pump output per minute, if the pump was selected taking into account the number of users. The result obtained is the minimum volume. If space allows for a larger tank, consider going a couple sizes larger. Each manufacturer has its own tank size. This row serves as an example, the volume is indicated in liters: 8, 10, 12, 18, 25, 30, 35, 40, 50, 60, 80, 100 and more.
It must be borne in mind that the useful volume of the tank, that is, the volume of water that it will give up when the power is turned off, is only 1/3 of its volume. This is provided that the air chamber has a free pressure of 0.2 bar lower than the pump shutdown pressure. Owners pump air above this value, therefore, the tank will give even less.
Storage tanks for water
Essentially, this is the same hydraulic accumulator, only much larger in size. If the hydraulic accumulator serves to protect the pump from frequent starts, then the accumulator tank also serves to create a reserve supply of water. But do not delude yourself, a tank of 500 liters will be able to release no more than 225 liters of useful water, with the correct pressure in the air chamber.
Therefore, it is easier and cheaper to install a simple tank of the required volume, but you will have to take water from it in a bucket. It can be installed in the attic, but the pressure will not be enough, and in winter you will need to take care to ensure that the water does not freeze.
Tip: by installing a system for automatically replenishing the storage tank, you can ensure uninterrupted water supply to your home.
DHW circuit with storage heater (boiler) and water circulation
A storage water heater (boiler) is a heat-insulated metal tank of a fairly large volume.
Most often, two heaters are built into the lower part of the water heater tank at once - an electric heating element and a tubular heat exchanger connected to the heating boiler (diagram for connecting the boiler to the boiler). The water in the tank is heated by the boiler most of the time.
The electric heater is turned on as needed when the boiler is stopped. Such a boiler is often called an 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 upward.
In the European Union, hot water systems in new houses 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 .
The water in the boiler is heated by a solar collector. If there is not enough heat from the collector, then the boiler or electric heater is switched on. Read: “DHW system with solar collector” .
Breakdowns and malfunctions
Typical DHW malfunctions include:
equipment failure;- noise in the system operation;
- the temperature of heating devices is below normal;
- weak hot water pressure;
- temperature spread of the coolant across the floors of the house;
- leaks in connections;
- corrosion of pipelines and shut-off valves.
Noises, as a rule, are caused by vibration of incorrectly installed pumps, wear of electric motor bearings, loosening of pipelines, and failure of control valves.
A decrease in the temperature of heating devices is caused by air pockets in the devices themselves, misalignment of the elevator unit, blockages and violation of thermal insulation in heating risers.
Low water pressure in the absence of blockages is most often caused by malfunctions of the booster pumps. Timely maintenance increases the reliability of the heating system.
DHW diagram with layer-by-layer heating boiler
| DHW diagram with layer-by-layer heating boiler and instantaneous water heater |
Recently, a hot water supply system with a layer-by-layer heating boiler has been gaining popularity,
the water in which is heated by a flow-through water heater. This boiler does not have a 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 drives water from the tank through a flow-through heater and supplies it directly to the top of the tank. Due to this, the consumer gets hot water very quickly
— you don’t 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 flow-through heater,
without sacrificing comfort.
The Galmet SG (S) Fusion 100 L layer-by-layer heating boiler is connected to the DHW circuit of a double-circuit boiler or to a gas water heater.
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 layer-by-layer heating boiler. As a result, the cost and dimensions of the DHW system equipment are somewhat smaller,
than with an indirect heating boiler.
The water in the boiler is heated in advance,
regardless of whether it is spent or not. The hot water reserve in the tank allows you to use hot water in the house for several hours.
Thanks to this, the water in the tank can be heated for quite a long time, gradually accumulating thermal energy in the hot water. Hence another name for the boiler - storage water heater.
The long duration of water heating allows the use of a relatively low power heater.
DHW. What it is?
DHW – hot water supply to meet the needs of the population, the temperature of the supplied medium reaches +75°C. This system is an important indicator of living standards. It is represented by a combination of several different elements:
- Water heater.
- Pump.
- Pipe
- Fittings.
The abbreviation in question is often used in regulatory documents. Different DHW systems are characterized by their own characteristics that must be taken into account.
Storage gas water heater - boiler
Storage boilers, the water in which is heated by a gas burner, are less popular in domestic hot water systems. Installing heating and hot water systems in a house with two gas appliances - a gas boiler and a gas boiler - turns out to be noticeably more expensive.
Storage 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 of water in the hot water system with liquefied gas.
Gas water heaters, like boilers, are available with an open combustion chamber and a closed one, with forced removal of flue gases and with natural draft in the chimney.
There are storage gas boilers on sale that do not require connection to a chimney . (Household gas stoves also operate without a chimney.) The power of the gas burners of such devices is small.
Gas boilers with a capacity of up to 100 liters are designed for wall mounting. Large volume water heaters are installed on the floor.
Water heaters use different methods of gas ignition - with a pilot wick, electronic with batteries or hydrodynamic ignition.
In devices with a pilot wick, a small flame is constantly burning, which is first ignited manually. A certain amount of gas burns uselessly in this torch.
Electronic ignition operates from the mains or a battery.
Hydrodynamic ignition is started by rotating a turbine, which is driven by the flow of water when the tap is opened.
Cold water supply
The cold water supply system is significantly different. Its features are as follows:
- Water is not heated.
- A separate highway is created for the system.
- Maintenance of the system is possible by installing several valves.
Due to the normal temperature of the water, it can be supplied under high pressure. This is due to the fact that heat affects important elements of the system.
How to choose the volume of a storage water heater - boiler
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 costs of its repair and maintenance, and the more space it takes up.
The size of the boiler is selected based on the following considerations.
It is generally accepted that the boiler volume, selected at the rate of 20-30 liters per person, will provide the minimum necessary comfort for using hot water in the house.
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 bathtub, it is necessary to use up almost all the water from the boiler with a volume of 80 - 100 liters.
Advantages and disadvantages of water supply options
Central water supply
Advantages:
- Purified water complies with SanPiN
- Quality control
- No pump required
Flaws:
- High price
- Possible low pressure
Artesian well
Advantages:
- Low cost of water lifting
- Adjustable pressure
- No chemical contamination, no disinfection required
Flaws:
- Filtering required
- May require removal of metal salts
- Construction costs
Surface well, well
Advantages:
- Costs are lower than for an artesian well
- Adjustable pressure
Flaws:
- Filtering required
- Cleaning required
- Primary water is contaminated
- Possible presence of harmful chemicals
- Disinfection may be required
Surface reservoir (river, lake, pond), rainwater
Advantages:
Minimal costs if a body of water is nearby
Flaws:
- Water, highly polluted, with the presence of chemicals used in agriculture
- Use without filtration, purification and disinfection is hazardous to health.
- High costs for water treatment
The comparison shows in what order preference should be given to water supply options.
How to choose boiler power for a DHW boiler
When choosing a boiler, you need 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 oC 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.
In 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 first turned on. In the future, the boiler almost always contains water that has already been heated to a certain temperature. To heat water to the required temperature in an acceptable time, heating devices of lower power are used.
But it’s still 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 , in which: t – water heating time, seconds (s); m – mass of water in the boiler, kg (mass of water in kilograms equals the volume of the boiler in liters); cw is the specific heat capacity of water, equal to 4.2 kJ/(kg•K); t2 – temperature to which the water should be heated; t1 – initial water temperature in the boiler; Q – boiler power, kW.
Example: The time for heating water by a 15 kW boiler in a 200-liter boiler from a temperature of 10°C (we assume that the water entering the boiler has this temperature) to 50°C will be: 200 x 4.2 x (50 – 10) /15 = 2240 s, that is, about 37 minutes.
Household products
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DHW scheme with water recirculation in the system
The use of a storage water heater in a domestic hot water system allows for the recirculation of hot water in pipelines. All hot water collection points are connected to a ring pipeline through which hot water constantly circulates.
The length of the pipe section from each point of hot water consumption to the ring pipeline should not be more than 2 meters.
The circulation pump of the DHW hot water recirculation system is small in size and has low power.
Water recirculation in the DHW system is ensured by a circulation pump. The pump power is small, several tens of watts.
Pumps for DHW, 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 hygienic certificate allowing use in drinking water supply systems.
The water in hot water supply systems is constantly renewed and the oxygen content in it remains quite high. Hot water is highly corrosive. In addition, hot water must meet 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, circulation pumps for hot water supply are noticeably more expensive than similar pumps for heating systems.
In some DHW pipeline designs, it is possible to create natural water recirculation, without a pump.
As a result of water circulation in the hot water supply system, hot water is constantly supplied to the sampling points.
In a DHW system with a storage heater and water recirculation, the water supply mode is more stable:
- Hot water is always present at the sampling points.
- Water can be collected simultaneously in several places. The temperature and pressure of water change slightly when the flow rate changes.
- You can take any, no matter how small, amount of hot water from the tap.
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 heated floor circuits to it in individual rooms. For example, in a 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 the 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.
Two-pipe heating system for a 2-story house
Truly comfortable living conditions can only be achieved by installing a two-pipe heating system. Its design allows you to regulate the temperature in individual rooms and save energy resources.
How does a two-way circuit work?
Unlike a single-pipe circuit, a two-pipe circuit consists of a pair of lines with different purposes: one of them supplies coolant, the second returns it back. The radiators are connected not in series order, but in parallel. One circuit, with heated coolant, extends from the riser to the radiators of both floors, the second is mounted to the boiler outlet and is also distributed to both floors.
Radiators are equipped with thermostatic valves that allow you to set a comfortable temperature. If desired, you can reduce the heating intensity partially or completely block the flow of water into the device.
Some devices are fundamentally embedded in the return line, for example, a membrane tank that regulates pressure, a circulation pump and a safety valve are traditionally installed in front of the boiler
In modern 2-story houses, two-pipe structures are used, since they are much more efficient than single-pipe ones:
- reduce pressure loss;
- do not require a powerful pump;
- keep the coolant temperature the same for each radiator;
- allow you to use many different thermal devices within one system (for example, radiators, convectors and “warm floors”);
- make it possible to repair and replace parts without compromising overall functionality.
The main disadvantage is the difficulty of self-installation - during assembly, consultation and supervision of professionals is required.
Successful solutions for installing a two-pipe system
There are many incarnations of various schemes, but when drawing up a project you should start from individual requirements.
The simplest diagram for arranging a heating system in a 2-story house. It is characterized by the following points: 2 circuits for heating and hot water production, liquid coolant, forced circulation (+)
A number of universal schemes are suitable for providing heat to houses of various sizes and number of floors.
Detailed diagram of two-pipe wiring for a one-story house with a fully equipped basement. The problem of thermal insulation of the floor in the basement was solved by connecting a water-based “warm floor” system
If you install additional equipment, such as a membrane tank, the capabilities of the heating system will expand.
A and B – two variants of the wiring device, upper and lower type. Additional equipment: expansion tank, Mayevsky taps, overhead line (+)
The following diagram combines the three most popular wiring diagrams.
Level 1 – dead-end wiring with parallel installation of both circuits; Level 2 – counter wiring, characterized by two-way radiator connection; 3 – collector wiring with improved balancing
All of the above schemes are suitable for heating a 2-story building.
Disadvantages of a hot water supply system with a double-circuit gas boiler or water heater
Clocking of a double-circuit boiler in heating mode
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. Hot water is prepared in a flow-through heat exchanger of the boiler. Read about the general disadvantages of a DHW system with a flow-through heater at the beginning of this article. But gas appliances with a flow-through heater have another problem - the difficulty of choosing the maximum power of a double-circuit boiler or hot water heater.
Most often it turns out that the required boiler power for preparing hot water is significantly greater than the power required to heat all rooms in the house.
As already mentioned in the article above, in order to obtain hot water at the required temperature and its maximum consumption, double-circuit gas boilers and water heating geysers have a fairly large maximum power, about 24 kW . or more. Boilers and heaters are equipped with automatic equipment, which can, by modulating the burner flame, reduce their power to a minimum, equal to approximately 30% of the maximum. The minimum power of a double-circuit gas boiler or water heater is usually about 8 kW. or more. This is the minimum boiler power, both in DHW and heating modes.
Due to design features, the gas burner of a double-circuit boiler or water heater cannot operate stably with a power less than the minimum (less than 8 kW). At the same time, to work with the heating system of a private house or autonomous heating of an apartment, the boiler in heating mode very often must produce 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 m2, and during the coldest five-day period of the heating season. In warmer periods, the productivity and power of the boiler should be significantly less.
Due to the fact that the boiler cannot operate with power below the minimum, problems arise 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 accept. As a result of inconsistency between the parameters of the boiler and the system, the double-circuit boiler begins to operate in pulse mode, “clocking” - as people say.
Operating in the “clocking” mode significantly reduces the service life of boiler parts and significantly reduces efficiency.
Read more: “Setting the power of a double-circuit gas boiler”
Clocking a gas boiler or water heater in DHW mode
Diagram of heating tap water with a double-circuit gas boiler or hot water column, depending on the temperature ( T oC) and flow rate ( Q l/min) of hot water. The thick line shows the boundaries of the Working Area. Gray zone, position 1 - clock zone of the boiler or dispenser (switching between ON/OFF).
For normal heating of water by a boiler or column, in the diagram the point of intersection of the temperature and hot water flow lines (operating point) must always be located inside the working zone, the boundaries of which are shown in the diagram with a thick line. If the hot water consumption mode is selected so that the operating point is in the gray zone, pos. 1 on the diagram, then the boiler and column will clock. In this zone, with a small water flow, the power of the boiler or dispenser turns out to be excessive, the boiler, dispenser turns off due to overheating, and then turns on again. Either hot or cold water comes out of the tap.
Read more: “Alternately cold and then hot water comes from the boiler.”
Low efficiency of double-circuit gas boilers and water heaters
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 further decrease if such a boiler has to operate in pulse mode, with the gas burner constantly re-igniting.
Please note that a double-circuit boiler operates at minimum power most of the time throughout the year. At least 1/4 of the spent gas will literally fly uselessly down the pipe. Add to this the cost of replacing prematurely worn-out boiler parts. This will be the price to pay for installing cheap heating and hot water equipment in your home.
What do you want - choose
If the power of a double-circuit gas boiler is more than 20 kW. , is selected based on heating the maximum required flow of hot water, then the boiler cannot provide economical and comfortable operation in low heating power mode and when heating water at low flow rates. The same can be said about the operation of a hot water column.
Most often, there is no need to prepare large flows of hot water in the house. For many people, it is much more important to ensure comfortable and economical use of hot water with low consumption.
For such economical owners, many manufacturers produce double-circuit gas boilers and water heaters with a maximum power of about 12 kW. and the minimum is less than 4 kW. Such boilers and heaters will provide more economical and comfortable heating and the use of hot water in quantities sufficient for taking a shower or washing dishes.
Before purchasing a double-circuit boiler or water heater, owners need to decide which mode of hot water consumption is more profitable and comfortable - with a large water flow or with a small one. Based on this decision, choose the power of the boiler or dispenser. If you want both, you will have to choose a hot water system with a boiler.
For shower lovers, for preparing hot water and heating houses and apartments with a heated area of up to 140 m2, with one bathroom , I recommend installing double-circuit gas boilers with a maximum power of 12 kW. They best suit 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 large houses and apartments with an area of more than 140 m2, I highly recommend using a hot water system with a stratified heating boiler and a double-circuit boiler, or with an indirect heating boiler and 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 be more expensive, but will provide an increased service life of the equipment, gas savings and more comfortable use of hot water.
Do housing and communal services have the right to come up with names for their services?
The state seeks to standardize the procedure for paying for housing and communal services, since it is carried out every month throughout the country. Therefore, a list of services has been compiled that have their own names. The organization does not have the right to come up with names, as this may lead to problems for residents of the house with calculations and confirmation of expenses.
The information above indicates that there are several different water supply and heating systems. When developing, the layout, area of the structure, climatic conditions and other points must be taken into account. Therefore, professional companies are involved in drawing up the project. If the proper amount of hot water is not getting into the house or the towel dryer is constantly cold, then there is a possibility that the design developed does not meet the established standards.
DHW circuit with sewerage heat recuperator
In Western Europe and around the world, various ways to save energy when operating a private home are popular.
After use, hot water from the house flows into the sewer and takes with it a significant part of the thermal energy that was spent on heating it.
Scheme for the recovery of thermal energy from sewerage wastewater into the hot water supply system
To reduce energy losses in the house, a scheme is used to recover (return) heat from sewage into the domestic hot water system of a private house.
Cold water passes through a heat exchanger before entering the DHW boiler. The wastewater from sanitary equipment is sent to the heat exchanger.
In the heat exchanger, two streams, cold water from the water supply and hot water from the wastewater, meet but do not mix. Some of the heat from hot water is transferred to cold water. The hot water boiler receives already heated water.
In the diagram shown in the figure, only those sanitary fixtures that operate with hot water flow are sent to the heat exchanger. This recovery scheme is advantageous to use with any method of heating water - both with a boiler and with a flow-through heater.
To recover heat from the drains of sanitary appliances, which first accumulate hot water and then discharge it into the sewer system (bathtub, swimming pool, washing machine and dishwasher), a more complex scheme is used with water circulation between the boiler and the heat exchanger while these devices are emptying.
Tips for the developer
For houses and apartments with permanent residence, I highly recommend using a hot water system with a stratified heating boiler and a double-circuit boiler, or with an indirect heating boiler and a single-circuit boiler. The boiler volume is at least 100 liters. The system will provide good comfort in using hot water, economical consumption of gas and water, as well as a smaller volume of waste into the sewer. The only disadvantage of such a system is the higher cost of the equipment.
With a limited construction budget, in small country houses for seasonal living, you can install a hot water system with a flow-through heater.
It is advisable to use a DHW circuit with a flow-through heater in houses with a kitchen and one bathroom, where the heating source and hot water collection points 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 disadvantages 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 device body. To install a boiler with a power of up to 30 kW or a gas water heater, a separate room is not required.
To prepare hot water and heat houses and apartments with a heated area of up to 140 m2, with one shower in the bathroom , I recommend installing double-circuit gas boilers with a maximum power of 12 kW.
In a DHW system with a gas water heater or a double-circuit boiler
The stability of the water supply mode will increase significantly if
a buffer tank is installed in the circuit between the heater and the water collection points
- a conventional storage electric water heater.
It is especially recommended to install such a buffer storage electric water heater near distribution points remote from the gas appliance. Read more: Connecting an electric hot water boiler to a double-circuit gas boiler or water heater
In a scheme with a buffer tank, hot water from a gas water heater or double-circuit boiler first enters the tank of the electric boiler - water heater
. Thus, the tank always contains a supply of hot water. The electric heater in the tank only compensates for heat loss and maintains the required temperature of hot water during the period when there is no water supply. An electric water heater with a small capacity tank is enough - even 30 liters, and using hot water will become much more comfortable.
DHW system with instantaneous water heater and built-in boiler or remote stratified heating boiler
will be somewhat more expensive. But here you will not need to spend expensive electricity to maintain the water temperature, and the comfort of using water will be the same as with an indirect heating boiler.
In houses with an extensive DHW network, implement 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 hot water system. True, the initial costs of its creation are the highest. It is recommended to buy boilers that are sold complete with a boiler.
In this case, the parameters of the boiler and boiler have already been 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 with a solid fuel boiler , then it is beneficial to install a buffer tank - a heat accumulator, to which you can connect a hot water supply system with water circulation.
Otherwise, to heat water in the house, an indirect heating boiler, additionally equipped with an electric heater, is connected to the solid fuel boiler.
It is beneficial 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 supply in the house, near the water collection points, an electric storage boiler - a water heater - is installed. There is no hot water circulation system in this option. It is more profitable to install your own separate storage heater near remote water collection points. In this case, electricity is spent more economically on heating water.
When water is heated above 54 °C, hardness salts are released from the water. To reduce scale formation
If possible, heat the water to a temperature lower than specified.
Instantaneous water heaters are especially sensitive to scale formation. If the water is hard, contains more than 140 mg
CaCO3 in 1 liter, then
the use of instantaneous water heaters, including those with stratified heating boilers, for heating water is not recommended.
Even small scale deposits clog the channels in the instantaneous heater, which leads to the cessation of water flow 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.
To heat hard water, it is better to choose a hot water storage system with an indirect heating boiler.
Salt deposits on the heating element of the boiler do not impede 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 the storage tank (boiler) with hot water. It is recommended to periodically perform thermal disinfection of the hot water supply system , increasing the water temperature to 70 ° C for some time.
More articles on this topic:
⇒ Connecting a layer-by-layer heating boiler to a double-circuit boiler ⇒ Why there is either cold or hot water from the boiler ⇒ Descaling the DHW heat exchanger of a boiler or column ⇒ Solar collector - water heater for a home, pool
More articles on this topic
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- Heating a private house with a wood-burning solid fuel boiler
- Norms and rules for planning a private house, cottage
- Air humidifier for apartments and houses - which one is better to choose?
- Radon indoors. Protecting your home from radon
- Canopy, canopy for external door
- Septic tanks and wastewater treatment stations Eurolos autonomous sewerage
- Do you need heated floors in a private home?
Dependence of the system on the heat source
The system can be classified according to a variety of criteria. If we consider them on a large scale, we can distinguish several options:
- Centralized are associated with the installation of a boiler room. It heats the medium, which is supplied to several multi-storey buildings at the same time.
- Locals are required to service only one structure. They are characterized by low power, since they are designed to heat a small volume of medium.
In industrial buildings, a system can often be installed that involves the use of secondary steam to heat the premises. This option reduces costs because thermal energy is reused.
Selection of heating radiators
It is impossible to give recommendations for all occasions on the choice of radiators. You need to choose the type of radiator by assessing the capabilities of your budget, the volume of the room and its area, as well as the size and number of windows, and the type of boiler. An important point when choosing radiators is the furnishings and design of the room. Therefore, we will consider the parameters of radiators, which are selected individually, taking into account the specifics of the situation.
The types of radiators are as follows:
- Aluminum . These are usually cast structures, characterized by low weight, low cost and fast heating. The disadvantages include the not very original appearance and the rapid decrease in water temperature.
- Bimetallic . Such radiators are more resistant to hard water, are intended for a centralized system, although they can be used for a private home, and have a good design. The cost of bimetallic radiators is quite high. Additional sections can be added or removed.
- Steel . These are heat devices with great efficiency, beautiful to look at, have a long service life, and cost less than the options discussed above. They heat up quickly, but also quickly reduce their temperature. The main advantage is the small volume of water for heating, which saves electricity and gas.
- Cast iron . The main advantages are corrosion resistance, slow temperature decline, beautiful design and long service life. The negative factor was the heavy weight and cost.
Which ones to choose?
Since cast iron, aluminum and bimetallic radiators contain a large volume of water, they are not suitable for an electric boiler. In this case, it is better to purchase steel models. For gas boilers you can install any radiators. If you purchase a structure that quickly reduces the temperature, then the house must be well insulated. Otherwise, the consumption of electricity or gas will be high.
Separation based on water supply principle
Installation of a DHW and cold water system can be carried out in two ways:
- With “deaf” wiring. The water supply pipe to the last water intake point ends in a dead end. This scheme is more beneficial for saving space and from an economic point of view, but can create inconvenience during the operation of the water supply system. Water will flow into the last node with a delay, and only after it reaches the plug will it begin to flow into the tap.
- With closed circulation wiring. With this method, water constantly moves in a circle, has the same temperature at each point of the system and reaches the user immediately after opening the tap. The peculiarity of this wiring method is advisable to use specifically for a hot water supply system - it is important to prevent sudden temperature changes in it.
In order not to unnecessarily complicate the plumbing in the house, it is more rational to use a combined option. The cold water supply system is carried out with the help of blind wiring, the hot one - with the help of circulation.
A simple diagram immediately shows the differences between different water supply schemes: 1 - standard, “dead”; 2 - with forced circulation; 3 - “blind” using a collector
Water and air heating
Heating can be water (using water or antifreeze as a coolant) and air (heat is carried throughout the house by air currents). Which option is more functional?
The author votes with both hands for the classic water heating system. The only convincing advantage of air as a coolant is that it is not afraid of freezing when the boiler is stopped.
The problem of water-type heating freezing is eliminated by filling the heating circuit with antifreeze
There are many more disadvantages:
- heating is much more expensive (it requires laying large cross-section air ducts throughout the house and installing a heat recuperator in the ventilation);
- It is installed only at the construction stage: known air channels are laid in the walls or above false ceilings;
- It forces you to sacrifice the usable area of the house, precisely because of the large diameter of the air channels, which compensate for the low heat capacity of the air.
Boiler and air heating lines
Single pipe system
The operation of a single-pipe distribution system occurs according to the following principle: there is a single pipeline that is closed. The coolant circulates through this pipeline. The coolant heats up as it passes through the boiler. Next, the coolant transfers heat to the radiators. And when it has already cooled down, it returns to the boiler again.
A single-pipe system has a single riser. It is located depending on the type of building. If it is a multi-story building, then this is a vertical arrangement. If it is one-story, then the location is, accordingly, horizontal. In order for the coolant to function through a vertical riser, a pump may be needed.
Pros:
- easy installation.
- quick installation.
- low costs for materials and equipment.
- stable hydrodynamics.
- minimal risk of accident.
Minuses:
- passing through all the radiators in the circuit, the water gradually loses its original temperature.
- heating elements heat up unevenly.
- the number of radiators that can be placed on one riser is limited.
Which option is better?
To understand which design of the heating system is better: open or closed, it is worth considering how they differ.
The main difference between a closed structure and an open one is the location of the expansion tank. In an open structure, it must be placed in the highest place of the house. But in a closed design, the tank can be installed anywhere, even on the same level as the boiler.
Insulation in a closed type of heat supply from the environment prevents air masses from getting inside. As a result, the service life of all equipment becomes significantly longer. Also, additional pressure is created in the uppermost components of the structure, which reduces the risk of air locks in the heating elements.
The open type of heating is distinguished by larger diameter pipes, which lead to additional inconvenience. In this case, the pipes have to be installed at a large angle to ensure circulation. Thick-walled pipes cannot always be hidden. In addition, in order to ensure correct hydraulics, it is necessary to take into account tilts, lifts, narrowings, turns, and connection options to radiators.
For a closed structure, pipes of a smaller circumference are needed. This makes the design cheaper
However, in such systems it is very important to ensure that the pump is installed correctly, otherwise it will become very noisy.
The closed type of heating, unlike the open one, is more durable and reliable. At the same time, it is able to maintain pressure at a constant level, and it is also possible to regulate it. The coolant in this design can be antifreeze rather than water. Simplicity of installation and quick start-up are also characteristic of a closed type of heating supply.
Among the advantages and differences, it is also worth noting the ability to connect additional equipment. Heating of this type is characterized by high efficiency, cost-effectiveness and the absence of the need for constant monitoring.
Of course, there are differences in the closed type, which cannot be classified as advantages. For example, the volume of the tank must be large and there must be an electrical network. Operation of a closed structure from other sources is possible, but only for a short time and in emergency cases.
The open design has a simpler installation scheme. It operates more silently than a closed one, and heats at a faster rate. You can fix faults in it very quickly, as well as turn it off completely. It does not need a power grid, nor does it need recharge in an emergency. Installation of the circuit does not require large expenses and a lot of time.
Air can get into the open type of heating, which causes various problems - for example, air congestion, rust. Unlike the closed type, such a system can boil or freeze.
The difference between the systems is quite significant. It is possible to say unequivocally which one is better only individually. To do this, it is worth once again emphasizing the main advantages and disadvantages of each system.
The closed design saves energy and supplies high-quality water, but the process of preparing this water itself is more complex and expensive.
The open design is very economical. However, due to long pipelines, the water there is of low quality. If you try to purify the water so that it has a better color and smell, then such a system will lose its dignity.
Water source
Basically, only cool water is supplied to a private home. Its heating for household needs is carried out by a local heat source. What can become a source of water?
The video in this publication can help you learn more about the installation of engineering systems in a country house.
Water supply main
If there is a main water metering station near your house, the problem can be solved by signing a contract with the local Vodokanal. After drawing up and approving the project, a water meter well is built, a connection is made into the main line and a water supply system is installed - a water meter with a pre-filter and shut-off valves.
Water pipe in a well
Suburban water metering station
In order to provide water
was uninterrupted, a storage tank is installed in the house connected to the country water line with water supply according to the schedule. The simplest solution is to install it in the attic: water will be drawn into the container when it is supplied to the water metering unit through a float valve, which prevents overflow, and will move to the water intake points on its own.
Water is independently supplied to the water metering unit from a tank placed in the attic
Unfortunately, this option makes it difficult to organize the provision of water and heat to a wooden house: for wooden beams, the weight of a storage tank of a couple of tons will be a large load. In this case, you can turn to plan “B”: the tank is mounted in an insulated basement or subfloor and is equipped with a station with a pump with a hydraulic accumulator.
Providing water
from a tank in the lower floor with a water supply station with a pump
Well, borehole
How to provide water
from a well or well?
- The well pump is equipped with a check valve, which will prevent water from draining from the water meter unit when the pump is turned off (see Belamos well pump);
- A pressure meter and an automatic relay are responsible for controlling the pump;
- A membrane tank is installed in the water supply circuit. Its function is to stabilize pressure and save pump life.
Providing water
from a well with a submersible pump
Useful: if the distance from the ground level to the mark of the complex of water intake structures is less than 8 meters, the pump can be surface-mounted. In this case, the check valve is installed on its suction pipe.
Scheme of independent water supply with a surface-type pump
Installation of heating and water supply in a house begins with the selection of a wiring diagram for engineering systems.
Cool water is distributed according to a dead-end circuit (in other words, it moves along the water wire exclusively during water tapping).
The wiring can be:
Serial wiring is common for Soviet-style buildings
Box for manifolds on water supply
Apart from dead-end wiring, recirculation schemes are used for hot water supply systems. A circular pump constantly pumps water between taps of the storage water heater. This ensures instant supply of hot water to all taps and constant heating of the towel dryer connections collected in the gap.
DHW supply with recirculation from indirect water supply
Like water supply , heat supply can be collector or sequential (tee). The first type of wiring is more often used with warm hydraulic floors: the high hydraulic resistance of small-diameter pipes laid in a screed reduces the length of one circuit by 100-120 meters.
Moreover, the heating distribution can be:
Traditional "one-pipe distribution system": batteries connected in parallel to a single dispenser
A positive quality of a single-pipe distribution system is its unconditional resistance to failures: as long as there is at least some difference at the ends of the filling, circulation in it continues. The downside is the significant temperature difference between devices for heating the room.
Dead-end two-pipe wiring: heating devices closest to the boiler are hotter than those further away, because a significant part of the coolant moves through them
This wiring allows you to bypass any obstacles and create several parallel branches of the heating system. However, jumpers between pours cause the difference between them to drop as they move away from the boiler.
The result is cooling of distant radiators right up to defrosting in severe frosts. The problem can be solved by balancing - limiting the permeability of the connections of the batteries closest to the boiler.
The Tichelman loop ensures the same temperature of the batteries without throttling the connections
Connection diagrams for heating devices
Installation of a heating system and water supply in a house outside the city includes, among other things, the installation of radiators. If panel-type radiators and convector heaters are installed only in the manner prescribed by the manufacturer, then sectional heating devices can be connected to the bottling or riser according to one of three schemes.
One-way connection - for a moderate number of sections
Diagonal connection to two fillings
The connections are connected exclusively to the lower manifold of the heater
What materials are best for installing heating and hot water
and cold water distribution?
Operating conditions
Heat supply and water supply to houses with independent water heating are used in greenhouse conditions in terms of loads:
- The pressure in the DHW circuit is equal to the pressure in the cold water supply line and in most cases can vary from 2 to 6-7 kgf/cm2;
- In the heating system, the pressure is even lower - 1.5 - 2.5 atmospheres;
Stereotypical pressure in an independent heating circuit
- There are no water hammers, and with little sanity of the homeowner there cannot be;
- Like home heating
,
the water supply
does not heat above 75 degrees.
Conclusions? Both pipes and devices for heating the room can be selected without taking into account the safety margin in case of force majeure, relying solely on standard operating parameters.
From the author’s point of view, polypropylene is an excellent choice. For cold water, pipes without reinforcement with a working pressure of PN 10 and higher are used, for hot water and heating - reinforced with aluminum or fiber with a nominal pressure of PN 20 - PN 25.
Water supply - home heating
made of timber, mounted with polymer pipes
It is worth paying attention: reinforcement is needed not so much for strength in relation to hydrostatic pressure (it is already excessive), but to reduce the elongation of the pipeline when heated. For unreinforced polypropylene it is 13 times greater than for steel, while for reinforced polypropylene it is only 3 times.
The photo shows firsthand the elongation of a polymer pipe without reinforcement when heated
How to provide water
and home
heating
from PP pipes (see Installation of a water supply system from polypropylene pipes)? They are connected by low-temperature soldering using a soldering iron with Teflon tips.
The instructions for the connection setup process are incredibly simple:
- Install a nozzle of the appropriate size for the pipe;
- Preheat the soldering iron to operating 260 degrees;
- If you are using an aluminum-reinforced pipe, clean the reinforcement in the soldering area with a shaver. Cleaning will enable the connector to weld with the inner polymer shell of the pipe and prevent its delamination due to aluminum corrosion;
Cleaning metal reinforcement with a shaver
- Place the connector on the nozzle and at the same time insert the pipe into it from the other side;
- After 5 seconds (for a diameter of 16-20 mm), remove the parts from the nozzle, connect them with a translational movement and secure;
- As soon as the plastic melt sets, move on to the next connection.
Installation of a fitting connection on polypropylene
Room heating devices
We recommend using metal sectional heating devices as radiators. They combine remarkable heat transfer per section (with a typical size of 500 mm along the collector axes - up to 205 watts) with the most affordable price (from 240 rubles).
These cheap room heating devices have excellent heat output
Legal basis for relations in the field of heat supply
The relationship between energy companies and consumers is regulated by the Federal Law on Heat Supply No. 190, which came into force in 2010.
Chapter 1 outlines the basic concepts and general provisions that define the scope of the legal foundations of economic relations in heat supply. It also includes the provision of hot water
The general principles of organizing heat supply are approved, which consist in creating reliable, efficient and developing systems, which is very important for living in the difficult Russian climate. Chapters 2 and 3 reflect the broad scope of powers of local authorities, which manage pricing in the field of heat supply, approve the rules of its organization, accounting for heat energy consumption and standards for its losses during transmission. The full power in these matters makes it possible to control heat supply organizations that are classified as monopolists. Chapter 4 reflects the relationship between the heat supplier and the consumer based on the contract. All legal aspects of connection to heat networks are considered. Chapter 5 reflects the rules for preparing for the heating season and repairing heating networks and sources
It describes what to do in case of non-payment under the contract and unauthorized connections to heating networks. Chapter 6 defines the conditions for the transition of an organization to the status of self-regulatory in the field of heat supply, the organization of the transfer of rights to own and use a heat supply facility.
All legal aspects of connection to heat networks are considered. Chapter 5 reflects the rules for preparing for the heating season and repairing heating networks and sources. It describes what to do in case of non-payment under the contract and unauthorized connections to heating networks. Chapter 6 defines the conditions for the transition of an organization to the status of self-regulatory in the field of heat supply, the organization of the transfer of rights to own and use a heat supply facility.
Users of thermal energy must know the provisions of the Federal Law on heat supply in order to assert their legal rights.
