Recirculation of hot water through the boiler

The water pressure in the boiler itself may not be sufficient to provide hot water supply. To recirculate hot water through boiler , it is necessary to correctly install the DHW system with the installation of a circulation pump.

In large country houses, experts recommend installing a hot water supply system (DHW) of a centralized method of heating water, through gas and an electric water heater (you can also use a single-circuit gas boiler). In this case, in order to provide the necessary supply of hot water, an indirect heating boiler must be installed in this system.

The volume of the boiler is calculated taking into account all people living in the house (for a family of 4 people, a 100-150 liter boiler will be enough). The water in the DHW system is heated using a heat exchanger, which is connected to a heating source (boiler, column).

The DHW tank has several inputs and outputs. The design feature of indirect heating boilers is that a coil is mounted in it in the form of a spiral metal tube, through which hot water from the boiler passes. Due to heat exchange between hot water in the coil and cold water in the boiler, the liquid inside the boiler is heated. This creates a preliminary supply of hot water for human needs.

The entire DHW system has a closed cycle of operation. If hot water is not used for a long time, it starts to cool down. When a person wants to use hot water, he will surely face the problem of initial absence. When you turn on the tap, the system itself is activated and water heating begins. But it may take several minutes before it heats up to the desired temperature.

So that you can use hot water immediately after opening the tap, they are installed in the system circulation pump, which ensures the recirculation of water around the circuit constantly, regardless of whether a person uses hot water or not.

Uninterrupted water recirculation through the boiler is carried out by installing additional equipment: an expansion tank, non-return and safety valves, an air drain valve.

Thus, the recirculation of hot water through the boiler takes place using a circulation pump, a heat exchanger and additional equipment, which is mounted into a single DHW system. As a result, a person does not have to wait for the water to heat up, letting water through for some time.

Recirculation boiler piping

One of the most important and complex processes for installing a hot water supply system is piping a boiler with recirculation, but it is quite possible to carry it out with your own hands.

One of the most economical and efficient water heaters for home and summer cottages, experts consider the indirect heating boiler. The water heating source can be gas, electricity or a heat exchanger. It is the heat exchanger that ensures the economical use of a DHW system with an indirect heating boiler.

The further functioning of the entire system depends on the correct piping of the boiler. The concept of piping can be defined as a feature of the installation and connection of the DHW system to a source of water heating.

When installing the boiler and the entire system with recirculation, you need:

• Set the recirculation point. It is usually located in the center of the heating vessel;
• Cold water is supplied to the lower hole of the boiler;
• The hot water outlet must be installed at the top of the boiler;
• The coolant pipe is connected from the top and goes down (the circulation of the heat exchanger water will pass along the circuit, the inlet of which will be at the top of the boiler, and the outlet at the bottom).
• The pipes must be supplied to the energy source according to the rules for the installation of materials, and connected using adapters. Valves and taps.

You should be aware that the efficiency of the DHW recirculation system depends on the home heating system. This increases the efficiency of the indirect water heater (boiler) by 35%.

The piping of the boiler with recirculation is carried out with a standard set of materials: taps, PVC pipes, adapters, fittings, pumps. You need to choose only high-quality certified products made from durable materials. The use of corrugated hoses and powder metallurgy material is strongly discouraged.

Boiler recirculation diagram

Recirculation of water in the DHW system is necessary in order to provide hot water to any point of the system without additional spilling. For this, a circuit is installed along which water from the boiler passes through the entire system, and then returns back to the boiler. Recirculation is carried out using a small pump that runs completely silent. Such a system helps maintain a stable hot water temperature anywhere in the house.

Among the common recirculation schemes, there are several main options:

• Installation of a three-way or servo-driven valve. This method is used for wall and floor models of boilers. Two pipes (two circuits) are connected to the boiler. One circuit is for heating, the other for hot water. The water heater in this system acts as the main heat carrier. When the water temperature drops, a servo-driven or three-way valve is used, which starts to work to heat the water. Heating is shut off at this time. After heating the water to the desired temperature, the heating resumes;
• Installation of two circulation pumps in one system. With this scheme, one of the pumps is designed to recirculate hot water through the heating system, and the other through the boiler circuit. This system initially provides normal water temperature in the boiler, and then in the heating system. A feature of this scheme is the presence of a thermostat and a mode switch, which allows you to turn off, if necessary, one of the systems;
• Application of the hydraulic arrow. It is used if there are more than two circuits in the house (heating, hot water, floor heating). This scheme is aimed at heating water, due to which all circuits are heated. This system has a significant drawback - when parsing water. The coolant may not be able to cope with meeting the needs of all people at the same time.

The choice of the method of heating water and heating, as well as the methods of its recirculation through the boiler, should be carried out in accordance with the clear calculations of all consumers and the capacity of the heat carrier. Boilers with three-way or servo-driven valves have an advantage among the main schemes.

Video about organizing hot water recirculation