HRVs tied into Forced Air Systems
My understanding is that HRVs should have dedicated ductwork sized specifically for lower ventilation flows. The system should also be balanced and commissioned.
However I’ve been seeing HRVs tied into Force Air Systems. What are the consequences of doing this? and how to advise the homeowner if they have this situation? Is this setup just wasting electricity or might it be contributing some fresh air while taking advantage of the some heat exchange? Can these systems work together if designed correctly or are the different fan mechanisms fighting each other? Should the homeowner disconnect the HRV from the Force Air System if it has already been installed?
I figure that when the Forced Air System is off the HRV system doesn’t distribute well because of the oversized ductwork, but is still of some benefit to dump some pre-conditioned fresh air into the thermal envelope?
When the Forced Air System is running, whether cooling or heating, can an appropriately designed connection to an HRV work like a CFIS setup or is there something about the balanced nature of the HRV that changes the physics of this situation?
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