Hydraulic compensators or balancing cylinders play a key role in heating and cooling systems where there are several circulation pumps, as they allow hydraulic separation of circuits (primary production circuit and secondary distribution circuit). The installation of a hydraulic separator is the best way to eliminate problems arising from the difference in flow between the heat and/or cold generators and the distribution network (pumps that burn easily or hot radiators even with the pump shut down), providing a proper balance between both circuits in all possible situations. In addition to this function, Ibaiondo compensators are designed to act as automatic air separators and sludge decanters: the air bubbles are released into the atmosphere through the purge with which they are equipped and the impurities are decanted at the bottom and evacuated through the discharge valve.


The hydraulic compensator is a collector where the flow flows of a heating or cooling system converge and mix. It creates an area with low load loss, which allows isolating the primary and secondary circuits, so that the flows of both circuits will depend exclusively on the flows of their respective pumps.

The flow of the secondary circuit shall be put into circulation only when the respective pump is switched on, allowing the installation to be adapted to the specific requirements of each moment. When the pump in the secondary circuit is turned off, all flow generated by the pump in the primary shall flow back through the compensator.

If the compensator is installed correctly, the flow rate of one circuit shall not affect the flow rate of the other circuit. The flow rate on each circuit shall be the exclusive function of the recirculating pump of each circuit.

There are three possible scenarios depending on the flows of the primary (production) and secondary (distribution) circuits :

1) The flow of the primary circuit (generator) is EQUAL to the flow of the distribution circuit : In this case the compensator is in a neutral position. The flows of the primary and secondary circuits are equal. This situation causes a cold return to the generator and can be interesting in condensing boilers, because at a lower temperature higher performance.

2) The flow rate of the primary circuit (generator) is HIGHER than the flow rate of the distribution circuit : This situation occurs when the heat generator pump provides more flow than is required by the part of consumption and causing part of the flow of the primary circuit to flow through the hydraulic compensator towards the return of the circuit primary, raising this one’s temperature. Installations with solar panels usually have this design.

3) The flow rate of the primary circuit (generator) is LOWER than the flow rate of the distribution circuit : Demand is higher than production. This occurs when all the secondary circuits are working at the same time and the generator pump does not have the capacity to provide the required power. It is also occurs in under floor heating systems with conventional boilers.