[masraum]

Originally Posted by berettafan

Some background- a/c is serviced annually. tech's take is for how old the system is it's running well but he recently said aging outdoor unit causing 'very high head pressures'. not sure what that means. house is about 21 yrs old and has a sealed crawlspace with concrete floor and sump pump. air handler is in crawlspace. no insulation under flooring (one story house). generally feels very dry when I have to go down there but not sure humidity level. This morning here it was 99% humidity, everything outside wet, fog, the whole nine yards. Temp was 72 and a/c not having to run. My understanding is when cooler at night a/c doesn't run but humidity builds.

Sounds like a 2 speed HVAC would essentially include the dehumidifying function via the lower speed. How much delta is there in price vs one speed or variable speed?

Yeah, if the weather is cool enough that the AC rarely runs, but the ambient humidity is high, the humidity in the house will go up higher than usual (if the AC isn't running, then it's not dehumidifying). I guess the question is how often do you have the situation where the humidity is high and the temp is low enough that the AC doesn't need to run. If that happens frequently enough then I would think you would want a dehumidifier. I wonder if you could just use one of those stand alone units while running the AC fan in the on position and that would be "good enough".