Counterflow heat exchangers

Moisture/odour transfer

In a counterflow heat exchanger there is neither moisture nor odour transfer. In this the extract and supply air ducts are completely separated. Compare this with, for example, a rotary heat exchanger that always has a certain amount of internal leakage between the extract and supply air. A leakage between the extract and supply air may mean that the used-up air from, for example, the bathroom or kitchen to some extent is brought back with the fresh supply air, which may cause some odour transfer.

Few moving parts

The REC counterflow heat exchanger consists of a heat exchanger with no movable parts, which means there are less parts that can break. In a rotating heat exchanger, heat is transferred using a rotor that spins, which results in a greater risk that some part may break.


With today’s new technology used in the counterflow heat exchanger you achieve the same or a higher efficiency than with the rotating heat exchanger. Previously, plate heat exchangers (counterflow heat exchanger) had a lower efficiency. This has been one of the main reasons for selecting a rotating heat exchanger. TEMOVEX Blue / RECOM 4 has up to 96% efficiency. Learn more about our FTX units here.

Defrost function

Efficient counterflow heat exchangers requires defrosting during the winter period. REC Temovex Blue has two different methods for defrosting or avoiding freezing. As a first measure, to prevent freezing, the unit is preset from the factory with a bypass control. This method means that one part of the out-door air passes by the heat exchanger.  The exhaust air will with this method heat up the exchanger, instead of stopping the supply air fan. The next step will be the so-called “stop defrosting” when the supply air fan stops short periods when there is a risk of freezing (a total of about 10-15 hours/year, in middle of Sweden).