ERV/HRV for Dehumidifying a Bathroom
My “HVAC guy” said that an ERV/HRV did not provide enough exhaust to effectively dehumidify bathrooms in a reasonable time—-even with a boost mode. I had previously gotten a quote from Zehnder and followed up with them to ask if they could put in additional exhaust ducts to the bathroom (and supply ducts somewhere else) to counter this and they said the might put in one more but they wouldn’t really recommend much more because “it would be too much.” Well… which is it?
My master bath is roughly 18’x 11’ (= 198ft2). I read that bathroom exhaust fans need to be about 1CFM per ft2. So do I need a 200cfm exhaust system? The ERV for the entire house is only 240cfm. Zehnder initially quoted me 2 tubes to the bathroom for 24cm and said they could put in a third for 36cfm but they wouldn’t recommend more. This seems too little. I know they have a boost mode, but a boost mode doesn’t boost the system that much.
Appreciate any insight. I’d love to not penetrate my envelope with bath fans and save the money as well.
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