Positive pressure ventilation sources a fresh drier air supply from either the roof cavity or from outside the home, filters it and then gently introduces this air throughout the home. It is commonly referred to as a ‘forced air ventilation system’.
For every cubic metre of fresh dry air introduced a cubic metre of moist stale air is exchanged. This stale air escapes through the gaps and tiny openings in your home.
This type of system suits almost every home and budget and can be installed where there is no roof cavity – they can even be installed outside the home. It is simple, effective and efficient.
A heat Recovery Air Ventilation system has two fans – one to introduce the fresh dry air and the second to exhaust the stale moist warm air. As the air passes through the Heat Exchange unit the heat from the exhausting air is transferred, via an aluminium or plastic heat exchange plate, to the incoming fresh dry air. These systems are up to 90% efficient.
These systems are more suited to new homes that are well insulated and air tight. This is the result of double glazing and high levels of insulation and modern construction methods.