Would a motorized AC coil bypass make sense?
I live in a 3500 sq ft house with 3 stories (inclusive of finished basement). HVAC is natural gas forced air furnace with an air conditioning coil and HRV. The current setup has symptoms of an oversized AC unit – short cycles (e.g., 3-5 minutes), uneven temperature between rooms/floors, insufficient dehumidification. The ducts are all rigid metal ducts and we sealed everything we could access when we were finishing the basement (all the trunk lines and take-offs from them). All the rooms in the house have at least one return, though I’m sure they’re probably super leaky since the returns use framing voids.
I have found that leaving the blower fan on continuously greatly reduces the temperature variation between room/floors but it has the side effect of driving humidity levels up quite a bit. It seems that a cure for this would be to install some sort of motorized bypass that would direct air through the AC coil when the thermostat asks for cooling but bypass it when only the blower is on, allowing the moisture on the coil to drain out rather than getting evaporated back into the conditioned air.
Does anyone make a product like that? Would it make sense to install one?
Our air conditioner seems to be working just fine so I’m looking for lower cost improvements I can make until we have occasion to install a new, properly sized, AC unit or maybe a heat pump and make other weatherization improvements to the house (e.g., improve air sealing and insulation in the attic).
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