Boiler-based heating systems can perform various functions. In addition to the actual space heating, boilers can also produce water heating for domestic purposes, for example for washing. Such systems can be installed not only in dachas and country houses, but also in private apartments, offices and production sites. Boiler is enough simple device and its installation, as well as piping the boiler indirect heating It’s quite possible to do it yourself. There are several schemes for such strapping, let’s consider them in more detail.
Boiler devices can have two water heating circuits.
- The first is water in the heating system, which, after heating, is supplied to the heating radiators. Such a circuit can be closed and special chemical additives can be added to such water to ensure uninterrupted operation radiators, descaling systems, and so on.
- The second circuit is water used for domestic purposes. It is intended for washing dishes, for washing. Therefore, this contour is not closed. Cold water enters it from the main water supply system, and then, as it is used, such water is drained into the sewer.
Principles for connecting boiler piping
When installing an indirect heating boiler piping system, you must remember the following principles:
- Point of entry cold water the boiler piping should be located at the lowest point of the system, but the hot outlet leaves the piping already at the top point.
- In this regard, the recirculation point is located almost in the geometric center of the piping.
If the specified principles for installing the piping are observed, the operation of the heating system will be as efficient as possible and the heat from the boiler will be efficiently transferred to the mass of incoming water.
Installation options for indirect heating boiler piping
Installation of water circuit piping on indirect heating boilers can be mounted in three main ways:
- With installation of a three-way valve,
- With the installation of two circulation pumps,
- Using a hydraulic arrow.
Please note that the use of a water recirculation system significantly improves the efficiency of the heating system and increases the efficiency of heating water and the room from the boiler.
Installation of an indirect piping system with a three-way valve
This installation option for an indirect piping system is intended for structures with big amount hot water. When designing the system, the installation of two heating circuits will be calculated. The first - the main circuit will be intended for the circulation of water entering the heating system. The second, additional circuit will heat water intended for domestic use. In order for the water coming from the water supply system to flow into one circuit or another, a three-way valve is used. The valve device is controlled from the boiler thermostat.
The use of a three-way valve when installing a heating system allows you to distribute the flow of water flowing to the boiler. The thermostat prevents the water from overheating and directs it to the circuits hot water when it reaches a certain temperature. This strapping scheme has a number of advantages and all our experts recommend it!
If the water in the heating system cools below a predetermined threshold temperature, the boiler thermostat switches the valve and supplies a new portion of the coolant to the circuit responsible for heating. The water receives heat from the boiler and heats up. The thermostat controls the heating temperature and prevents the water from overheating and therefore damaging the system. Once the set temperature is reached, water from the circuit is directed into the system. The water temperature is measured directly in the boiler heating circuit.
The moment of obtaining information about water temperature is very important. If the water in the tank for domestic use has a set heating temperature higher than in the heating circuit of the heating system, the system may begin to work incorrectly. In this case, switching to heating the heating circuit will not occur.
There is an option for installing an indirect heating boiler with two circuits. Choice possible option It also depends on the water in your water supply. If the water in the main channels has a high degree of hardness, then it would be wiser to use a system with a three-way valve. Otherwise, the dual-circuit system may quickly fail due to clogging.
Installation of indirect heating boiler piping with two pumps
Another option for installing a boiler piping system with an indirect heating system could be the use of two recirculation pumps. A check valve must also be installed in the system.
IN in this case Two separate heating circuits are installed in the system: heating circuit and water heating circuit for household needs. Each circuit has its own recirculation pump, which directs heated water into the system circuits.
Both indirect heating circuits are mounted in parallel to the boiler. The boiler circuit has priority during installation and when used in the system. Thus, the circulation pump of the boiler system is located before the heating system pump. As with the previous version of the system, a temperature sensor is used to control both circuits, which redistributes water to the heating circuits.
In addition, the system has a check valve, the purpose of which is to prevent mixing of heated water flows.
The principle of operation of such a system is that as the temperature of the water decreases, it is directed for heating and further heating system.
A system with two circuits and pumps can be installed with two heating boilers. Each of these boilers will have a separate power supply and will be responsible for heating water in one of the circuits: heating or for domestic use.
The heating system from boilers ensures fairly rapid heating of water in the heating system. The boiler usually takes an hour to do this. Thus, while heating occurs in the boiler for the hot water supply circuit, cooling of the heating systems does not occur.
Description of the operation of the hydraulic heating system
A boiler-based heating system may include more than two circuits. For example, a heated floor system can be used as an additional heating circuit. In addition, it may include other elements.
To regulate water flows in the heating circuits, a hydraulic arrow is used. Simply put, it is a system for distributing coolant flows, which is somewhat reminiscent of an ordinary railway switch. Also, during operation, the hydraulic arrow equalizes the pressure in several circuits of the system.
Each circuit in complex heating systems with multiple circuits has its own recirculation pump. At the same time, different pressures can be created in different parts of the heating system. The difference in pressure readings must be balanced. This is precisely why manifolds and hydraulic arrows can be installed in complex systems. In addition, in order to equalize pressure indicators, specialized balancing valves can be used.
Such a complex system has many nuances when adjusting and therefore, when installing it, it is recommended to use the services of specialists.
Beneficial coolant recirculation
The use of a recirculation system allows heating systems to receive hot water from the tap almost instantly, without long waits. In this case, a ring coolant line is formed in the heating systems. Water constantly flows through this line and heats up. As a result, waiting for heating at household use hot water is practically eliminated.
To ensure that the water in such a circuit constantly moves, a recirculation pump is built into it. It is recommended to pass this constantly hot stream of water through devices that require constant heating, for example, through a heated towel rail.
Piping an indirect heating boiler: video
To install a hot water supply system (DHW), there is Several variants, some of them are double-circuit and single-circuit boilers with a separate boiler.
If in a dual-circuit device A small heat exchanger is already built in to heat water for domestic hot water, but in a single-circuit system with a boiler, the task of heating water for domestic needs is assigned to it.
Double-circuit boilers are usually equipped relatively small capacity for DHW, therefore they cannot provide the desired temperature for many consumers for a long time.
Types of gas boilers with indirect heating boilers
Eat two options water heaters for DHW:
- indirect heating (IH);
- direct heating.
BKN connects to the installed gas boiler. Inside it there is a heat exchanger (this can be a pipe twisted in a spiral or a “tank-in-tank” design).
Hot water from the heating system circulates through this heat exchanger, heating the water in the boiler. The latter is connected to the cold water supply network (CWS), and from the collapsible pipe the hot water supply is supplied to consumers.
Direct heating boiler can be compared with a conventional gas boiler heating. It also has gas-burner and a water tank. The burner heats the water in the tank independently of the central heating system.
Important! When installing a BKN, it is necessary to estimate the power that will be spent on DHW. If there are many consumers and use water frequently, The boiler power may not be enough for heating, and the temperature in the rooms will be lower than the set one.
In this case, it is advisable to replace the boiler with a more powerful one, or use a different type of water heater.
Schemes for connecting a boiler to a single-circuit boiler
Exists three ways connecting the boiler to the boiler.
Direct connection of the water heater to the heating system
IN this option BKN is included in the heating system, in series or in parallel with other radiators. The simplest and most ineffective scheme is not recommended for use and is given for reference.
Photo 1. Scheme of direct connection of a water-heating gas single-circuit boiler to the heating system.
If the boiler temperature is set below 60 °C, this scheme becomes even less economical, and the water takes a very long time to heat up.
Temperature increase
Added to the connection diagram three-way valve — special device, which switches the movement of coolant when the temperature in the water heater tank drops to DHW and vice versa.
Thus, if the DHW water cools down, The heating is temporarily switched off.
All boiler power is redirected to DHW.
The temperature on the device in this scheme is set higher ( usually 80-90 °C).
And the heating temperature is regulated by a three-way valve.
Reference! The boiler temperature must be set at 5 °C higher than the required water in the domestic hot water supply.
Using a thermostat in a water heater and automation
If a thermostat is installed in the BKN (a device that gives a signal when the set temperature is reached), and the boiler controller has contacts for connection boiler thermostat, then this circuit is the most preferable.
In this case, the boiler electronics know about the temperature of the water in the DHW system, and it decides itself where to direct its power: for heating water in the BKN or for heating.
Photo 2. Thermostat for a water heater in a heating system, with it you can find out data on the water temperature.
Materials and tools
Materials:
- Pipes, shut-off valves, check valves- not applied to them special requirements: use the same materials as for working with hot water supply or heating systems.
- Expansion tank— a separate one is required for the domestic water supply system; it serves to prevent sudden pressure changes when opening/closing taps.
Attention! The tank must be designed for use with hot water, such devices are usually designated special markings.
- Circulation pump— as a rule, a separate pump is installed in the heat exchange circuit with the water heater.
In addition, in DHW systems with recirculation, a separate pump is required to circulate water in the DHW circuit.
This will eliminate the need to wait for hot water to flow through the pipes long length from the place where the water heater is installed: the water will immediately be hot.
- Wires and small electrical wiring— if you plan to connect the water heater thermostat to the boiler automation.
- Fasteners- especially in the case wall installation, also for securing pipes and pumps.
- Standard plumbing set of sealants, seals, gaskets.
Tool:
- gas key;
- spanners various diameters;
- Adjustable wrench;
- building level;
- hammer drill, screwdrivers, screwdriver;
- Minimum set for an electrician: knife, wire cutters, electrical tape, phase tester.
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Installation process: how to connect
Ideally, the boiler should be located as far as possible closer to the heating boiler to minimize heat loss.
Cold water is always supplied to the bottom pipe of the boiler, and hot water is drawn from the top.
- Select a location for the water heater so that it does not interfere and is easy to maintain. Mount brackets, stands, and secure it to them.
- Connect to the HVS network: make a tap, install a shut-off valve and a coarse filter.
- Through a tee, take the cold water line to consumers, connect the second output to the boiler through a safety valve.
- Connect the domestic hot water line to the boiler, not forgetting about the expansion tank on it. In addition, install bypass taps so that you can disconnect it from the circuit during maintenance.
- Now connect the boiler to the gas boiler according to one of the given diagrams. Don't forget to turn off the boiler and shut off the system before connecting!
- Connect electronics, sensors, pumps according to the instructions.
Startup and testing
To ensure that there is hot water in the house or sanitary premises in production, an indirect heating boiler is used. Connection to the boiler is carried out in several ways, depending on the importance of providing hot water supply. If space heating is more important, then it is connected to the system in series, and for better provision of hot water - in parallel.
Provide your home with hot water
Unit design
Externally, this device resembles a simple storage electric boiler. There are containers different sizes depending on the amount of fluid consumed. The water heater consists of the following elements:
- tank in a casing with a layer of thermal insulation;
- steel or brass pipeline made in the form of a coil;
- thermostat pipe;
- magnesium anode;
- hot water circulation pipes;
- pipes for connecting the heating system.
From this video we will learn the operating diagram of a single-circuit boiler and an indirect heating boiler:
There are some designs where, instead of a coil, another container is installed in which the heat exchange of the liquid occurs. Interior reservoir must be made from of stainless steel. Used as thermal insulation mineral wool, polyurethane, polystyrene, etc. These materials also protect the tank from mechanical damage.
Principle of operation
The operating principle of this device is based on the heat exchange of liquid from the heating system with water from the hot water supply circuit. Hot coolant from the heating system enters the coil through the upper pipe.
Passing through it, the coolant heats the water inside the tank. The degree of heating is controlled by a special temperature sensor, and as soon as the required temperature is reached, the valve will block the movement of water along the coil. When the liquid cools, the valve opens and the heat exchange process begins again.
Connection diagram indirect boiler through the upper pipe of the coil allows you to provide the maximum volume of heated water. Other water heater designs work on the same principle.
Types of water heaters
Currently, two types of indirect heating boilers are known: simple and with built-in control. Control elements refer to temperature sensors and devices that ensure water flows into the heat exchanger and stops it.
All operation of this equipment occurs automatically. To start it, you need to connect the inlet and outlet pipes of the hot water supply, the supply of cooled liquid and the comb for distributing the heated coolant. Modern models tanks have equipment for heat accumulation.
Such devices are very useful when there are frequent power outages. These structures usually have enhanced thermal insulation and large reservoir volumes. Recently, recirculation boilers have become popular. Their difference is additional pipes for hot water intake.
The nuances of tying tanks
Indirect heating tanks are easier to install together with all equipment than to install in already existing system. The boiler installation location should be close to the heating boiler and be level to prevent the water heater from skewing.
At the outlet of the hot water tank, it is necessary to install a membrane accumulator to protect against thermal expansion. It is recommended to use ball valves as shut-off valves, as they are more reliable.
All fastening work on walls should be carried out using special brackets and brackets. All pipelines to the tank must be connected only in a straight line, without unnecessary bends.
Connection to a single-circuit system
A single-circuit heating system with an indirect heating boiler involves the use of two circulation pumps. They perform the task of separating coolant flows.
Such installation of a water heater primarily contributes to the operation of the hot water supply circuit. The action of the pumps is regulated by a thermostat, which is built into the tank. To prevent mixing of coolant flows, a check valve is installed in the system before the pumps.
As a result, the pumps operate alternately, that is, when pumping is turned on in the water supply circuit, it is turned off in the heating system. The connection diagram for an indirect water heater is as follows.
The difference between this connection is the absence of additional heating of water for hot water supply. The water is heated only by the boiler. The general connection of equipment is carried out in three stages:
- Using hoses and pipelines, the water heater is connected to the boiler piping.
- Circulation pumps and shut-off valves are being installed.
- Lastly, a three-way sensor is installed to monitor temperature changes.
In such a system there is one important drawback: If the equipment fails, the hot water supply stops.
Installation in a double-circuit heating network
In order to correctly connect an indirect heating boiler to a double-circuit system, it is necessary to take into account that the operation of the heating system and water heating must occur simultaneously. This is the main difference between their operation in a single-circuit circuit.
The connection occurs in a parallel circuit. The only drawback It is the impossibility of a high-quality supply of coolant to the heating system if there is a high consumption of hot water.
For correct use The boiler uses a three-way valve. It ensures uniform distribution of coolant between the circuits. This connection is most often used and is most convenient for one-time consumption of hot water.
Hot water supply, without which comfortable living in modern housing is impossible, can be established by connecting an indirect heating boiler. Such units are much more profitable and efficient in operation than traditional ones. flow heaters thanks to higher power and efficiency. We will consider what options for connecting the boiler are used later in the article.
How does an indirect heating boiler work when connected to a heating boiler?
The installation of modern water heaters guarantees the supply of hot water in the proper volume at several distribution points - in the bathroom, kitchen, etc. Specifications the selected boiler must meet the water consumption requirements at comfortable temperature in the required volume. To ensure rapid heating in short term, it is necessary to correctly calculate the power of the water heater. For example, when consuming water in volumes of 500 liters per hour, a tank with a capacity of 100 liters or more is required.
Main elements of the heating system:
- Heating boiler;
- A pump that ensures constant circulation of water;
- Three-way valve;
- Hose with connections for connection to the pipeline system;
- Indirect heating boiler.
The indirect heating unit looks like a simple one storage boiler, powered by electricity, and performs the same tasks of creating a hot water supply. The main difference is the operating principle used using a heating boiler for heating.
The basic kit of the indirect heating device includes:
- storage tank in a casing, surrounded by a layer of thermal insulation;
- coil built-in for water circulation;
- Sleeve for connecting a temperature sensor;
- Pipe for connecting the boiler to the water supply system;
- Recirculation line (on some models).
The operating principle of the device is based on heating the coolant passed through the coil storage tank. When interacting with water, heat is transferred from the coil with a simultaneous increase in both temperature and pressure in the tank. During operation, it is necessary to monitor the degree of heating using the setting function desired temperature, avoiding limit values. When connecting an indirect heating boiler, the use of temperature sensors will help with this. When the water heats up, the temperature sensor signals the pump or three-way valve that the required temperature has been reached, and the water in the coil stops circulating. A similar principle underlies the operation of the sensor when the coolant cools.
When connecting, several different piping schemes can be used with a single principle for supplying cold and discharging heated coolant: cold water enters from below into a container for indirect heating, and heated water is discharged to the water supply. As heated water passes through the coil, it gives off heat and comes out from below. This connection option allows you to maximize the volume of heated water.
The heating scheme can be described as follows: when the hot flow is directed to the user, the cold water supplied from below acts in the form of a piston, and, passing through the heated coolant, the cold flow heats up and moves to the upper part of the tank.
The piping of an indirect heating boiler is carried out according to the principle of piping a radiator, differing only in the need to stop the circulation of water in the coil after reaching the desired temperature. To solve this issue, a three-way valve or an additional pump connected to the built-in thermostat is used. It is possible to use a dead-end DHW or circulation circuit. The first option will require additional opening of the tap to drain the cooled water in the pipes.
Simple principles of connecting to a double-circuit boiler
Using an indirect heating unit has its advantages and disadvantages. TO positive aspects applications of this device include:
- the ability to connect various heating sources;
- ability to connect with various types heat sources;
- uninterrupted supply of hot water supply;
- no additional energy consumption;
- the ability to use heated water for any purpose due to the absence of communication between the coolant in the heating system and the heated water.
The disadvantages of this connection include high initial installation costs and the need for additional free space for mounting equipment.
When connected according to this diagram to gas device, equipped with a circulation pump and automation, the valve control process, based on the signal supplied by the water heater thermostat, is carried out by the boiler.
When using a three-way valve, the water heater circuit has priority over the heating circuit. It is recommended to use this scheme in the presence of a large-capacity tank, as well as in conditions of using water of high hardness, which interferes with the normal functioning of the hot water supply circuit.
The connection is based on a dual-circuit heating device, which provides for parallel operation of heating and supplying heated water. It should be borne in mind that if there is a large demand for hot water, such a scheme for connecting an indirect heating boiler can negatively affect the existing heating system. For this reason, it is recommended to carry out the main consumption within the DHW using a boiler, limiting the use of water from the boiler to a minimum.
Connection to a double-circuit boiler follows a simple scheme:
- 1. A three-way valve is installed immediately after the pump responsible for water circulation.
- 2. The temperature sensor is connected directly to the pump.
- 3. After the water reaches the temperature set on the regulator, the valve closes.
- 4. The water flow circulates within the heating system.
During installation, the choice of priority function is taken into account: if the most important is DHW, the installation is performed in parallel with the heating system, and if heating plays a dominant role, it is installed in series, without using a temperature sensor.
Connection to a single-circuit heating unit
To connect an indirect heating boiler to a boiler with one circuit, a circuit using 2 circulation pumps can be used. This connection is based on the principle of separating water flows through pipelines using pumps. When making this type of connection, priority is given to the DHW circuit, which is achieved only by adjusting the switching algorithm. The pumps are used according to a signal sent by a thermostat built into the tank. To prevent mixing of flows, a check valve is installed in front of the pumps.
Operation according to this scheme is similar to connecting to a dual-circuit device. R The difference is that the temperature sensor must control the operation of 2 pumps alternately: if the DHW pump is turned on, the heating pump is turned off, causing the coolant in the system to cool. If the volumes of domestic hot water are small, there will be no noticeable deterioration in heating performance.
A feature of working with a connection to a standard single-circuit device is the absence of a water heating function for DHW, and, therefore, only the boiler capacity will be used to supply heated water.
The connection is made as follows:
- 1. The boiler is connected to a single-circuit boiler using the provided hoses and pipes.
- 2. A circulation pump is installed in the system.
- 3. A special three-way sensor is installed that controls the heating process to the required temperature.
When installing a boiler connected to a single-circuit heating device, one thing should be taken into account: serious drawback– if the equipment fails, the supply of heated water is impossible due to the lack of backup source for heating.
If you decide to install an indirect heating device, you should take into account a number of recommendations from specialists that will allow you to carry out the installation competently and efficiently. When choosing a device, it is based on the standard hot water needs per user. The optimal choice would be a container calculated based on 20 liters of water per consumer.
- 1. During installation, provision should be made for grounding.
- 2. Compensation for thermal expansion and amortization of possible water hammer occurs due to the installation of a hydraulic accumulator on the output line.
- 3. The installation location should be in close proximity to the outlet, thereby ensuring the ability to turn on the boiler if the boiler is turned off or breaks down.
- 4. To facilitate the operation process and provide protection, taps are installed on the mains, allowing you to disconnect the device from the heating system at any time.
- 5. To heat the water faster, the device should be installed at the highest possible height above the radiators.
- 6. Installation of equipment will be easier if the location is chosen close to the heating unit, with mandatory control of the correct orientation of the pipes in relation to the pipeline.
- 7. Heated coolant is supplied from the top of the device, and cooled water comes out from the bottom.
Hot water in taps has long ceased to be a luxury. Today this is one of the mandatory requirements of normal life. One of the possibilities for organizing hot water supply for a private home is the installation and connection of an indirect heating boiler.
What is an indirect heating boiler and what are they?
A water heater or indirect exchange boiler is a tank of water in which a heat exchanger is located (a coil or, like a water jacket, a cylinder within a cylinder). The heat exchanger is connected to a heating boiler or to any other system in which hot water or other coolant circulates.
Heating occurs simply: hot water from the boiler passes through the heat exchanger, it heats the walls of the heat exchanger, and they, in turn, transfer heat to the water in the container. Since heating does not occur directly, such a water heater is called “indirect heating”. The heated water is used for household needs as needed.
One of important details in this design there is a magnesium anode. It reduces the intensity of corrosion processes - the tank lasts longer.
Kinds
There are two types of indirect heating boilers: with and without built-in controls. Indirect heating boilers with built-in control are connected to a heating system powered by boilers without control. They have a built-in temperature sensor, their own control that turns on/off the supply of hot water to the coil. When connecting this type of equipment, all you need to do is connect the heating supply and return to the appropriate inputs, connect the cold water supply and connect the hot water distribution comb to the upper outlet. That's all, you can fill the tank and start heating it.
Conventional indirect heating boilers work mainly with automated boilers. During installation, it is necessary to install a temperature sensor in a certain place (there is a hole in the housing) and connect it to a certain boiler input. Next, they wire the indirect heating boiler in accordance with one of the diagrams. You can connect them to non-volatile boilers, but this requires special circuits (see below).
What you need to remember is that the water in an indirect heating boiler can be heated slightly below the temperature of the coolant circulating in the coil. So if your boiler operates in low-temperature mode and produces, say, +40°C, then the maximum temperature of the water in the tank will be exactly this. You won't be able to heat it up anymore. To get around this limitation, there is combined water heaters. They have a coil and a built-in heating element. The main heating in this case is due to the coil (indirect heating), and the heating element only brings the temperature to the set one. Also, such systems are good paired with solid fuel boilers— the water will be warm even when the fuel has burned out.
What else can be said about the design features? In large-volume indirect units, several heat exchangers are installed - this reduces the water heating time. To reduce the heating time of water and to cool the tank more slowly, it is better to choose models with thermal insulation.
Which boilers can it be connected to?
Indirect heating boilers can work with any source of hot water. Any hot water boiler is suitable - solid fuel - using wood, coal, briquettes, pellets. You can connect to any type of gas boiler, electric or liquid fuel.
It’s just that, as already mentioned above, there are models with their own controls, and then their installation and wiring is more simple task. If the model is simple, you have to think through a system for regulating the temperature and switching the boiler from heating radiators to heating hot water.
Tank shapes and installation methods
An indirect heating boiler can be installed on the floor or hung on a wall. Wall-mounted options have a capacity of no more than 200 liters, while floor-mounted ones can hold up to 1500 liters. In both cases there are horizontal and vertical models. When installing wall version The fastening is standard - brackets that are mounted on dowels of a suitable type.
If we talk about shape, then most often these devices are made in the shape of a cylinder. In almost all models, all working terminals (connection pipes) are located at the rear. It's easier to connect, and appearance better. On the front part of the panel there are places for installing a temperature sensor or thermostat; in some models it is possible to install a heating element - for additional heating of water when there is a lack of heating power.
According to the type of installation, they are wall-mounted and floor-mounted, the capacity is from 50 liters to 1500 liters
When installing the system, it is worth remembering that the system will only work effectively if the boiler power is sufficient.
Connection diagrams and features
There are two principles for connecting an indirect heating boiler: with and without priority for heating hot water. When heating with priority, if necessary, all the coolant is pumped through the boiler heat exchanger. It takes a little time to heat up. As soon as the temperature reaches the set temperature (controlled by a sensor, thermostatic valve or thermal relay), the entire flow is again directed to the radiators.
In schemes without priority for water heating, only a certain part of the coolant flow is directed to the indirect water heater. This results in the water taking a long time to heat up.
When connecting an indirect heating boiler, it is better to choose a scheme with priority - it provides hot water in required quantity. At the same time, heating does not suffer much - 20-40 minutes are usually enough to heat the entire volume of water, and 3-8 minutes to maintain the temperature at a flow rate. During such a time, no house can cool down enough to feel it. But this is provided that the boiler power is comparable to the boiler power. Ideally, the boiler is more productive, with a margin of 25-30%.
General rules
To provide normal operation of all appliances connected to the hot water comb is installed at the outlet of the boiler expansion tank for hot water (not for heating). Its volume is 10% of the tank volume. It is necessary to neutralize thermal expansion.
Also, shut-off valves (ball valves) are installed in each connection branch. They are needed so that each device can be used - a three-way valve, a circulation pump, etc. — if necessary, disconnect and service.
Check valves are usually also installed on supply pipelines. They are necessary to eliminate the possibility of backflow. In this case, connecting an indirect heating boiler will be safe and easy to maintain.
Installation next to the boiler in a forced circulation system (with 3-way valve)
If the system already has a circulation pump, and it is installed on the supply side, and the forced heating boiler can be placed next to the boiler, it is better to organize a separate circuit that comes from the heating boiler. This connection of an indirect heating boiler is implemented with most wall-mounted gas or other boilers that have a circulation pump in the supply pipe. With this connection diagram, it turns out that the water heater and heating system are connected in parallel.
With this piping method, a three-way valve is installed after the circulation pump, controlled by a temperature sensor (installed on the boiler). One of the outputs of the three-way valve is connected to the boiler pipe to connect the heating. A tee is cut into the return pipeline before entering the boiler, and a pipe is connected to it to drain water from the heat exchanger. Actually, the connection to the heating system is completed.
The operating procedure of this scheme is as follows:
- When information is received from the sensor that the water temperature is below the set temperature, the three-way valve switches the coolant to the boiler. The heating system turns off.
- The entire coolant flow goes through the heat exchanger, the water in the tank is heated.
- The water heats up enough, the three-way valve redirects the coolant to the heating system.
As you can see, the circuit is simple, its operation is also clear.
Scheme with two circulation pumps
Pir installation of water heater in the system in circulation pump, but not next to it, but at some distance, it is better to install a circulation pump in the circuit on the water heater. Connecting an indirect heating boiler for this case is shown in the diagram below.
The circulation pump can be installed either on the supply pipe or on the return pipe. In this scheme there is no three-way valve; the circuit is connected through ordinary tees. The coolant flow is switched by turning the pumps on/off, and it is controlled by a temperature sensor, which has two pairs of contacts.
If the water in the tank is colder than that set on the sensor, the power circuit of the circulation pump in the boiler circuit is turned on. When a given degree of heating is reached, the contacts of the pump close, which drives the coolant into the heating system.
Scheme for a non-volatile boiler
In a scheme with a non-volatile boiler, in order to ensure priority for the boiler, it is desirable that it be located higher than the radiators. That is, in this case it is desirable to install wall models. IN ideal— the bottom of the indirect water heater is located above the boiler and radiators. But such an arrangement is not always possible.
The circuits will also work when the boiler is located on the floor, but the water will heat up more slowly and in the lower part it will not be hot enough. Its temperature will be comparable to the degree of heating of the return pipeline, that is, the supply of hot water will be less.
At non-volatile heating The movement of the coolant occurs due to the force of gravity. In principle, you can connect an indirect heating boiler using traditional scheme- with a circulation pump in the circuit for heating it. It’s just that in this case, when the electricity is turned off, there will be no hot water. If you're not comfortable with this twist, there are several designs that will work with gravity systems.
When implementing this scheme, the circuit that goes to the water heater is made with a pipe with a diameter 1 step larger than the heating one. This ensures priority.
In this scheme, after the branch, a thermostatic head with an overhead sensor is installed on the heating system. It runs on batteries and does not require external power. The thermohead regulator sets the desired water heating temperature (not higher than the boiler supply temperature). While the water in the tank is cold, the thermostat opens the supply to the boiler, and the flow of coolant goes mainly to the boiler. When heated to the required degree, the coolant is redirected to the heating branch.
With coolant recirculation
If present in the system, constant circulation of water through it is necessary. Otherwise it won't work. All consumers can be connected to the recirculation loop. In this case, hot water will be constantly circulated by the pump. In this case, by opening the water at any time, you will immediately receive hot water - you will not need to wait for cold water to drain from the pipes. This is a positive thing.
The negative is that by connecting recirculation, we increase the cost of heating water in the boiler. Why? Because the water cools down as it runs around the ring, therefore the boiler will be connected to heating water more often and will spend more fuel on it.
The second disadvantage is that recirculation stimulates the mixing of water layers. During normal operation, the hottest water is at the top, from where it is supplied to the DHW circuit. When stirring, the overall temperature of the supplied water drops (at the same settings). However, for a heated towel rail this is perhaps the only way out.
How to connect an indirect heating boiler with recirculation? There are several ways. The first is to find special indirect units with built-in recirculation. Very convenient - the heated towel rail (or the entire loop) is simply connected to the corresponding pipes. But the price of such water heater options is almost twice as much as the price of a conventional tank of the same volume.
The second option is to use models that do not have an input for connecting the recirculation circuit, but connect it using tees.
