Reply To: Positive pressure systems and heating

[Ian McChesney]

Hi Johnny
As we head towards winter the temperature of the air blown from a positive pressure system sourcing from the ceiling cavity will become increasingly cold, especially in evenings and throughout the night, because it reflects ambient external temperatures rather than any short term heat storage offered by a ceiling cavity during the day. Under still night air ceiling cavities can even become colder than ambient.
So, no surprises that people feel cold from positive pressure systems. And it is a different ‘cold’ than that referred to by Consumer – they are talking about mixing the heat that is already contained within the room to minimise stratification and maximise its warmth effectiveness; a PP system introduces an additional source of cold air which will diminish the warmth in the room.
I wrote a report on home ventilation systems for EECA in 2009 – the report is on their website and link is below:
http://www.eeca.govt.nz/sites/all/files/home-ventilation-report-06-09.pdf

Bear in mind that this report is 6 years old now, and there are a better range of balanced pressure/heat exchange systems now available
regards
Ian

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