The suction it creates pulls air from your rooms. If the room isn't well sealed it will be pulling air in from outside, say through badly sealed windows, negating some of the point of it. I guess the question is how well sealed does it need to be?
I'd say have a close look at the heat exchanger that is on offer and see what you think. My unit was a relatively small sealed all plastic looking affair. How much energy actually moved between the incoming and outgoing air with such small surfaces involved I don't know -- especially when the differences in air temps between the in and outgoing air are relatively small -- I strongly suspect the efficiency of that unit was not great.
Given the cost of these systems I'd be asking them for the numbers and guarantees of efficiency.. I think you'd also want well insulated ducting - my system had non insulated ducts that ran quite long lengths in the roof - suspect during cold evenings any heat actually recovered by the heat exchanger would have taken big losses running to and from the outlets in those ducts.
Often branded as "heat recovery" as they draw air from the roof space (a dubious idea from an air quality perspective), which is warm in some conditions. Studies have found that the roof space is typically cold at time when one would want their house heated....
This is what I've never understood about these systems. There was one where I previously lived in Auckland. In summer the roof temps were often over 50 degrees, and there was no point during the night that it would less than the temp in the house. So in summer, there was no point using it. In winter the roof temp was often cooler than the house temp, so again, it wouldn't get used!
There must be some roof, house types or location where it can work. All this did was blow gross brown rings onto the ceiling. And once a couple of heatpumps were installed the HRV was turned off and blocked off.
Ceiling ducts for HVAC are typically R0.6 to R1.0, not a lot of insulation but a lot better than none. I checked two HVAC suppliers in NZ and both only stocked R0.6 and R1.0.
This is what I've never understood about these systems. There was one where I previously lived in Auckland. In summer the roof temps were often over 50 degrees, and there was no point during the night that it would less than the temp in the house. So in summer, there was no point using it. In winter the roof temp was often cooler than the house temp, so again, it wouldn't get used!
There must be some roof, house types or location where it can work. All this did was blow gross brown rings onto the ceiling. And once a couple of heatpumps were installed the HRV was turned off and blocked off.
That's why I changed mine from pulling ceiling cavity air through a cheap ineffective filter to pulling fresh air through a HEPA / charcoal filter. There's no heat available when you need it, it smells off due to the old wood and various poisions up in our ceiling space, the sock filters went from white to gray to dark gray really quickly.
Are you subscribed to our RSS feed? You can download the latest headlines and summaries from our stories directly
to your computer or smartphone by using a feed reader.
Trusted
ID Verified
