Is there a preferred approach to preventing mold in attic AC only ducts? (We have snowy winters (New England) and baseboard heating)
If we pick registers with the tightest kind of seal for the winter and block the return, this still allows a small amount of humid, warm air to enter the ducts... leading to condensation and eventually mold, right? (If this is the preferred approach, which brand of registers should we ask for?)
If we run the system on fan for x minutes every hour, that moves a lot of humid warm air through ... does this approach work by basically heating all ducts to room temperature (water doesn't condense on a room-temperature mug)? Doesn't this mean we are heating an R8 space (all the ducts) losing some of the benefit of our R38/39 attic insulation? Could we heap additional fiberglass insulation on top of all the ducts or pay for better-than-R8 insulation? Shouldn't the fan be controlled by a thermostat on a duct surface (vs simply running x minutes every hour)?
Should we run a stand-alone dehumidifier all winter long? (It would be in the lower level of our split-level house because it's loud)
Can we have the AC system provide whole-house dehumidification without cooling in the winter? Or is the cooling and dehumidifcation inseparable?
What's a sensible amount of money to spend to prevent mold in a New England house that needs only 2 or 2.5 tons of cooling? (How bad $$ would it be if we got mold?)
Thanks in advance for your advice!