What is an indirect water heater

Owners of private properties often wonder how to provide hot water to the kitchen and bathroom, while carrying the minimum cost of heating water? The answer may be the use of an indirect heating boiler for this purpose. On the one hand, this unit has a rather high cost. But the savings will be noticeable during the operation of the device, since it does not have its own heating system, but uses an external heat carrier (hot water from the heating system).

Why do I need a water heater indirect heating

For water heating, a variety of storage water heaters of various types is used. This may be an electric storage water heater, installed mainly in apartments. Gas boilers are used in private homes, and are designed so that the burner and the tank with the heated liquid are in the same housing. But the undoubted advantage in terms of profitability occupy indirect type devices.

Indirect heating boilers recommended to purchase paired with single boiler. Such a kit is more expensive when compared with the price of a double-circuit boiler, and can occupy considerable space. But the possibility of an indirect type of apparatus to provide all households with the necessary volume of hot water supply with a constant temperature is an indisputable advantage over a double-circuit boiler.

Existing methods of heating water have drawbacks: heated water is only enough for a couple of points, while the temperature of the liquid is subject to fluctuation. If, for example, at one time to wash the dishes and take a shower, the temperature drop will be felt, which causes discomfort.To take a shower, you will have to ask the household not to open hot water in the kitchen.

The water heater of indirect heating makes it possible to use hot water at the same time to all households, and its quantity is limited only by the capacity of the tank. The liquid in the tank warms up evenly throughout the volume and when opening the tap it is not necessary to wait until cool water runs off.

Boiler device

The unit looks like a large cylinder with a capacity of up to several hundred liters. Devices are wall and floor. The latter can interfere with very large volumes of liquid, so it is impossible to hang them on the wall. The boiler body is made of metal (stainless or enameled steel) or plastic. The standard unit consists of the following elements.

1. External metal or made of plastic tank.
2. Thermal insulation strip between the inner tank and the case, which can be from different materials (foam rubber, mineral insulation, polyurethane and others).
3. Cold water pipes.
4. Pipes to exit the already heated fluid.
5. Heat exchanger - “coil”, Which passes through a carrier of heat, and gives thermal energy to the liquid that surrounds it. It is made of brass (which is more preferable) or of steel. Due to the serpentine form, the area of ​​contact with the liquid and, accordingly, the heat transfer increases. Some models have 2 heat exchangers. An indirect heating boiler with two heat exchangers is designed in such a way that the former is traditionally used (the heating system is connected to it), and the latter can use an alternative source of heat (solar energy, hot water from the centralized main). There are units that do not have a coil, and an internal tank (tank in the tank) acts as a heat exchanger.
6. Thermostata, the task of which is to give a signal to the automation of the heating boiler and synchronize its operation with the boiler (with sufficient heating of the water in the tank, the heating stops).
7. Magnesium anode. Its role is to protect the inside of the tank from corrosion. This is due to the fact that the potential of the metal of the reservoir is greater than that of the electrode, and the latter will be subject to destruction.Therefore, it is important to check in time the condition of the anode and, if necessary, change it to a new one.
8. Security systemsconsisting of a safety (emergency) valve and reverse. The latter protects the apparatus from the reverse flow of water, and the safety valve - from the overpressure that occurs when the liquid expands during a rise in its temperature.
9. Chipper (flow damper), which helps to evenly distribute the incoming liquid and eliminates turbulence.
10. Audit hole. Through it you can carry out maintenance and repair work.

There are also indirect heated boilers. They contain not only traditional coils as a source of heat, but also built-in heating elements. This boiler is convenient to use in the summer, when heating is not required.

Principle of operation

Indirect water heaters are connected to the heating system. With indirect heating boiler can be used as a gas boiler, and electric boiler. They should be located as close as possible to the boiler and connected parallel to the main layout. A circulating pump and a three-way valve are built into the system, which allows the DHW system to be separated from the heating system. The whole construction works quite simply:

• cold water is poured into the tank through the inlet pipe;
• at this time, a heated fluid flows from the heating system (CO) along the coil;
• cold water in contact with the heat exchanger begins to set the temperature;
• through the outlet nozzle, the already heated fluid enters the places of consumption.

How to choose

It is very important to correctly calculate the volume of the unit before purchase. This indicator will directly affect the speed and quality of the provision of heated water to the consumer. Water consumption depends on the number of people and appliances using it. For example, to wash the dishes, you need from 20 to 25 liters. For washing - 9-20. To take a shower, you have to spend up to 90 liters of water. And for taking a bath - about 180 liters.

Therefore, you should focus on the needs of users and their number, and select a unit with a displacement of 50 liters to 1000. When choosing, consider: the larger the displacement, the higher the cost of the device.

Indirect heating boiler per 100 liters suitable for a family of 2 people.This should take into account whether there are pets in the house that require regular bathing (for example, a dog). For such purposes, a good option would be the Protherm (Proterm) WH B100Z 1165

Heater Protherm WH B100Z 1165

The capacity of the tank in this unit is 100 liters. In addition, a titanium anode is used to protect the tank, and polyurethane is used as insulation, minimizing heat loss.

Also a good option for a small family can be considered an indirect heating boiler Drazice OKCV 125 NTR, which has horizontal placement type.

Boiler Drazice OKCV 125 NTR

The internal tank of this wall unit Drazitsa is designed for 125 liters. The wall unit is compact and does not take up much space.

Indirect heating boilers are in good demand. with stainless steel housingsuch as Premier Plus 100.

Premier Plus 100 Heater

The light weight of the unit is ensured by the use of DUPLEX stainless steel. Installation option can be wall and floor. The heat exchanger in it has the “coil in the coil” design, due to which the liquid will heat up faster.

Indirect heating boiler volume of 200 liters will allow you to comfortably use hot water to a family of 3-4 people, such as, for example, the model Gorenje GV 200.

Water heater Gorenje GV 200

The manufacturer provides a warranty on this device for 24 months. The unit has a steel tank with enamel coating, and the inner tank can withstand a working pressure of 6 bar. Installation of heating elements in this device is not provided, but there is a recirculation circuit. The time taken to raise the water temperature from 10 ° C to 60 ° C is 15 minutes.

For a family of 5 people or more, an indirect heating boiler is required. with a volume of 300 liters. Atlantic 300 will cope with the tasks in excess. This is a floor boiler indirect heating.

Atlantic 300 water heater

Internal tank device with antibacterial coating. Applied heavy-duty enamel based on titanium with cobalt. In this indirect heating boiler of 300 liters, a system is built in to prevent water from overheating, there is protection against possible freezing of the liquid. It is possible to connect the circulation of hot water to the device, and there is also a hole for the installation of the heating element for a voltage of 220 V. To accommodate a boiler for indirect heating of 300 liters with the boiler, a separate room (boiler room) is required.

For industrial use, for example, for canteens, cafes and restaurants, large volumes of sanitary water are already required, therefore the boiler is indirectly heated. on 500 liters with TENG Hajdu STA 500 C will completely provide GVS all these points.

Heater Hajdu STA 500 C

The internal tank of this unit has a high-strength coating with the use of glass enamel. Thanks to the built-in powerful heat exchangers, a very rapid increase in the temperature of the liquid occurs. This unit can serve at the same time several points of water intake. During the summer period the device can work from the built-in heating elements. A safety thermostat is installed to protect the tank from bursting. The possibility of using this indirect heating boiler with a recirculation system has been implemented. Manufacturer's warranty - 7 years applies only to the tank. For all other elements - 2 years.

Pricing is influenced not only by volume, but also by the manufacturer (additional options in devices, materials used, etc.).

Binding indirect water heater

For the correct operation of the unit it is necessary to make the correct binding of the boiler of indirect heating.

Three-way valve application

Most often produced by tying scheme using a three-way valve. This valve redirects the coolant either to the unit or to the heating system.Priority is given to heating the fluid in the unit. Redistribution of flows occurs automatically. The valve switches from the incoming signals of the thermostat located in the boiler body.

The use of two pumps

This scheme of the boiler indirect heating involves use of 2 pumps to ensure circulation. When installing the device, you need to create a separate circuit that must be connected in parallel to the pipes for heating. The fluid flow is directed alternately turning on the heating and heating circuits. Starting the necessary pumps is engaged in a temperature sensor located in the unit.

Recycling

Another variant of the indirect heating boiler piping scheme is recycling. This kind of strapping allows you to get hot water without waiting for the cool water to drain.

Indirect heating boiler piping diagram

Such a scheme involves the creation of a looped highway with a constantly heated fluid through it. Often in this scheme the heated towel rail crashes.

Advantages and disadvantages

The indirect type devices have their strengths and weaknesses.

Merits

The advantages of the unit include:

• low in comparison with other types of heating cost of obtaining a hot liquid, while no electricity consumption;
• the ability to produce large quantities of hot water;
• the possibility of simultaneous supply of sanitary fluid in different directions;
• ability to connect to different heat sources (solar battery, gas boiler and electric boiler, solid fuel boiler).

disadvantages

The main disadvantages of indirect players:

• high cost of all equipment;
• it takes longer to heat the liquid in the tank when compared with an electric or gas boiler, while the temperature in the heating system drops, which affects the intensity of the heating of the rooms;
• boilers, especially large sizes, occupy a lot of space - to install the whole structure sometimes requires a separate room.

Thus, indirect type units are an ideal option for an inexpensive source of hot water for private houses, as well as for establishing hot water supply in bars, canteens, restaurants and other locations where a large amount of heated fluid is required. Although the initial investment is significant, further savings will be substantial.