Energy recovery always acts like a temperature rectifier between the two air streams. Output control is therefore not necessary as long as the extract air temperature corresponds to the setpoint/room temperature.

There are different pressures on the supply and extract side of a ventilation system – depending on the installed components and the arrangement of the fans.

If humid air is cooled down, the relative humidity rises until condensate is formed. If the outside air is so cold that the extract air is cooled below the freezing point of the condensate, it can freeze and block the heat exchanger on the extract air side partially - or in extreme cases even completely.

Since the first energy crisis in 1973, heat recovery in HVAC systems has become the benchmark in the industry – even though there was previously no obligation to use it and no mention of minimum thermal efficiency. With the implementation of the Ecodesign Directive...