The photos above are the best advertisement for our SEVi decentralised HRV System.
They just show the peak of the iceberg - the visible parts of a standard mechanical HRV system. We suppose the extract ducts are filthy on the entire length, whilst the air intake ducts seemed to be visible clean. Not really a surprise because the extract valves absorb the dust and dirt, coming from the room and the fresh intake air ducts blow the dirt & dust back to the room. Perfect circulation!
To bring some clean air back into our clients home , we did an extensive cleaning and changed the filters completely.
It´s a pitty that the most standard mechanical heat recovery ventilation systems do not have a display where the client can see clearly when it´s time for the next cleaning.