Double purge sector
Rotor purging during overpressure on the outdoor air side
The purge sector causes that the outgoing air existing in the heat storing mass ducts is purged out by the outdoor air. No outgoing air can get into the outdoor air.
A complete separation of outdoor air and outgoing air for regenerative rotary heat exchangers is ensured only with a functioning double purge sector.
In devices without double purge sectors a small proportion (< 3%) of the outgoing air can be transferred to the outdoor air by co-rotation. If this cannot be permitted, then the co-rotation can be eliminated by employing purge sector systems.