Can virus particles enter to the ventilation system via a heat wheel ?

In the case of heat wheels, the carry over transfer is limited mainly to gaseous pollutants, for instance to tobacco smoke and other smells. In the case of properly operating equipment, heat wheels with purge sector practically do not transfer particles – this applies also for virus particles. The main concern in older equipment is the air leakage from exhaust side to supply side.

This depends on pressure difference and condition of seals. If fans create higher pressure on the exhaust air side, the air leakage can increase from a few percent to 15%. If needed, the pressure differences can be corrected by dampers or by other arrangements. Because the leakage does not depend on the rotation speed, it is not needed to switch rotors off, but inspection for older equipment can be recommended.