Most often, residential private houses are heated by a water heating system in which heated liquid (not only water can be used, but also special antifreezes - non-freezing liquids) moves through pipes and transfers heat to heating radiators.
Heating systems can be divided into two types:
- with natural fluid circulation through the system,
- with forced movement of the coolant.
In the case of forced circulation, the coolant moves thanks to the circulation pump.
The principle of the coolant
In practice, all owners of autonomous heating systems, without exception, sooner or later are forced to solve the problem of reducing the volume of coolant in the heating system and use make-up pumps.
The only difference is that in open systems the coolant decreases systematically and fairly quickly, and in closed systems it decreases more slowly.
When circulating through the heating system, the heat carrier is heated by a heat generator, passes through radiators and gives up part of its heat to heat the premises. Then the cooled coolant returns to the boiler and heats up again to go to the heating radiators. This cycle is repeated again and again while the heating system is operating.
If the volume of liquid significantly decreases in volume, then, in addition to reducing the efficiency, heating equipment may fail , and the system will be “airy”. In order to avoid such a nuisance, they also use make-up pumps for the boiler room, integrating them into special automatic make-up units.
The reasons for the decrease in coolant volume
In the case of an open heating system, the coolant constantly evaporates from the expansion tank, since the liquid is hot and the tank is open. In addition, evaporation occurs in the air vent, in the safety valve, with increasing pressure, at the joints of the equipment (micro-leaks are formed). The inner surfaces of metal pipes undergo constant corrosion, which reduces their thickness, and, as a result, the system becomes more space empty with liquid.
During the removal of air from the system through Mayevsky taps, a coolant leak also occurs. In addition, during the next preventive work, part of the liquid is drained when the mud filters are cleaned, pipes are repaired, or equipment that fails is replaced.
Manual heating system refill
If an autonomous heating system is organized in the house and there is no common water supply or the water is often turned off, you can get out of the situation by using the manual pump through which the system is fed and take liquid, for example, from any available container, bottle and can.
Tip: you can use a classic pressure pump as a make-up pump to fuel the heating system.
Water is connected before the circulation pump to the "return" of the heating system. This is necessary because at this point the lowest temperature and pressure are minimal.
Manual recharge has its drawbacks:
- high and constant labor costs;
- you must constantly monitor the marks on the pressure gauge or in the expansion tank.
This problem is easily solved by installing a make-up pump in the heating system.
To control the pump requires:
- check valve;
- pressure switch or electrical contact pressure gauge;
- storage capacity (if there is no central water supply, if water is used as a heat carrier) or if non-concentrated antifreeze is poured into the system (when its concentrate is used, simply add water)
The principle of operation of the automatic recharge unit
After detecting a pressure drop in the system, the adjustable pressure sensor is activated and the pump contacts are closed. The coolant is added either from the water supply system or from the storage tank. After reaching the necessary coolant pressure in the system, the pump turns off.
Such a device has another indisputable plus - with the help of a recharge pump, it is possible to pump coolant into the system without resorting to disassembling the heating system. This is necessary to repair or replace the coolant.
How to pick up
The charge pump of the heating system has a different task than the circulation pump, which ensures the movement of the coolant along the heating circuit. The feed pump should provide greater pressure with a small flow. Vane, vortex and monoblock pumps are suitable .
Make-up equipment usually has a low efficiency (only about 45%). But in this case, this is not significant. The make-up pump for heating is switched on only periodically and does not work for long.
When buying a recharge pump, you should pay attention to:
- On the pressure that is needed. It must necessarily be higher than the pressure in the "return" of the heating system, and, in addition, it will need to overcome the resistance of the pipeline and pressure sensor.
- At the expense. For closed heating systems, about 1/2 percent of the total volume of coolant in the boiler circuit and heating system is considered the norm.
The volume of coolant is determined either empirically or at the rate of about 15 liters / kW of boiler power.