Sarah Deeds posted in HVAC, DHW & Plumbing

Energy analyst is telling me that no "through wall" HRVs are on the approved list. I am not seeing the lunos or the panasonic whisper comfort....Is this correct?

Some of them are not HVI rated but still provide the benefits of a balanced ventilation system with heat recovery. There are efforts underway to modify code to simplify their code compatibility. For example, some are rated to European standards and it may be as simple as recognizing those. A work around is to model them as balanced without heat recovery. These require fan power inputs and those ratings from manufacturer spec sheets are acceptable if they are not available in the HVI database. Although, there's an archaic ASHRAE rule requiring a minimum amount of duct work on exhaust fans if not properly rated for sound—really have to get lost in the weeds to find that. To avoid this, install both the ductless systems and a bath fan with continuous operation capability for compliance. There will likely be a penalty losing w/o heat recovery, but at the ADU scale it's not as significant. Almost certainly not an issue when using a HPWH. Hopefully they simplify ductless ventilation requirements in the next code cycle.


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