What is the actual effectiveness of Zehnder’s “Bypass” mode?
I’ve received a quote from Zehnder for our PGH build in NW Ontario (10,000HDD). They spec’ed the Q600 Comfoair unit to meet our needs. At a max CFM of just over 350cfm it’s grossly oversized (not a bad thing). Zehnder designs their systems to run at medium speed continuous. Our ventilation requirements for the size of home is around 130-160cfm depending what formula you use. Our home will have an interior volume of around 32,000cu Ft.
I love the idea of bypass mode as shoulder season overheating is a legit concern. I’ve read conflicting articles about the actual effectiveness due to the very low CFM.
Is anyone aware of any studies done regarding the actual effectiveness, or any first hand experience?
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I was hoping for a little more data on this subject.
How effective is 350CFM of 15 degree C (or even 10 degree C) outside air at cooling 32,000 cu ft of indoor air that is 25 degrees C?
What is the w/CFM of the unit in bypass mode? Usually the issue with using an ERV like this is the blower power use is high, CFM is pretty low and not much delta T, the COP is not that great.
Depending on static pressure it looks like the w/CFM ranges from .35 at 175cfm+ up to .71.
I guess a better question would be: if we are continuously ventilating at the designed rate ~160ish~ cfm how much actually (free) cooling are we receiving with a temp delta of say 15c? I wouldn’t necessarily consider the COP data to be valuable as we would be ventilating at the designed rate regardless.
160cfm*1.08*24F(15C)=~4000BTU.
Not nothing but not much. At about 60W blower power, the COP is actually pretty decent.