In the event that a system with natural circulation is in good condition, pipes and nozzles have not rusted and are not clogged, it is best to connect a circulation pump into the system. Connection of the circulation pump is the easiest way to translate the system from natural circulation to forced. After installing the pump in the system, the necessary pressure appears and circulation improve.
If the pipes in the system are clogged with a drop, then the conditional passage of the pipes is reduced and, as a result, hot water (coolant) can be poorly circulated, or not at all to separate radiators. To clean the pipes from the scale, it is recommended to disassemble them and blow well or rinse. If the pipes cannot be cleaned, the pressure in the system should be increased using a circulation pump.
In the event that in the system there is a gas boiler, it is recommended to replace the discoveries of the expansion tank with the same, only diaphragm (with a closed principle of functioning). If in the system there is a boiler for solid fuel to replace an open expansion tank strictly prohibited. A closed tank performs all the same functions as open, with the difference that water (coolant) does not contact open air.