Most often, residential private houses are heated by a water heating system, in which a heated liquid (not only water, but also special antifreezes - non-freezing liquids can be used) 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.
Principle of coolant operation
In practice, without exception, all owners of autonomous heating systems sooner or later have 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 rather quickly, while in closed systems it decreases more slowly.
When circulating through the heating system, the coolant is heated by a heat generator,passes through radiators and gives off part of its heat for space heating. Then the already cooled coolant returns to the boiler and heats up again to go to the heating radiators. This cycle repeats over and over again as long as the heating system is running.
If the volume of liquid decreases significantly in volume, then, in addition to reducing efficiency, heating equipment may fail, and the system will "air up". In order to avoid such a nuisance, they use make-up pumps for the boiler house, embedding them in special automatic make-up units.
Reasons for reducing the volume of coolant
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 an increase in pressure, at the equipment junctions (micro-leaks are formed). The internal surfaces of metal pipes undergo constant corrosion, which reduces their thickness, and, as a result, there is more space not filled with liquid in the system.
During the removal of air from the system through Mayevsky's taps, the coolant also leaks. In addition, during regular maintenance work, part of the liquid is drained when dirt filters are cleaned, pipes are repaired, or failed equipment is replaced.
Manual replenishment of the heating system
If an autonomous heating system is organized in the house and there is no common water supply or water is oftenturn off, you can get out of the situation using a manual pump, through which the system is replenished, and take liquid, for example, from any available container, bottle and can.
Tip: You can use a classic pressure test pump as a make-up pump to feed your heating system.
Make-up is connected in front of the circulation pump to the "return" of the heating system. This is necessary because at this point the lowest temperature of the coolant and the pressure is minimal.
Manual feeding has its drawbacks:
- high and constant labor costs;
- you have to 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.
Pump control requires:
- check valve;
- pressure switch or electrocontact pressure gauge;
- accumulation tank (if there is no central water supply, in case of using water as a coolant) or if non-concentrated antifreeze is poured into the system (when its concentrate is used, just add water)
The principle of operation of the automatic make-up unit
After detecting a pressure drop in the system, the adjustable pressure sensor is triggered and the pump contacts are closed. The coolant is topped up either from the water supply or from the storage tank. After reaching the required pressure of the coolant in the system, the pump turns off.
Such a device has another indisputable plus - with the help of a make-up pump, you can pump coolant into the system without resorting to disassembling the heating system. This may be necessary to repair or replace the coolant.
How to choose
The booster 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 make-up pump should provide more pressure with a small flow. Vane, vortex and monobloc pumps are suitable.
Make-up equipment usually has low efficiency (only about 45%). But in this case it doesn't really matter. The boost pump for heating is switched on only intermittently and works for a short time.
When buying a make-up 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 the pressure sensor.
- At the expense. For closed heating systems, it is considered normal for leakage of approximately 1/2 percent of the total volume of coolant in the boiler circuit and heating system.
The volume of the coolant is determined either empirically, or at the rate of about 15 liters / kW of boiler power.
