basement humidity

10 years ago

As a wrap up my basement project I am starting to determine the actual humidity down there and how to deal with it. I had run a dehumidifier for years without really knowing what the humidity level was. The unit broke, I bought a new one and and am now going down a path of trying to get the humitdy down from 60% or so to 50%.

Obstacles are the location of the humidier...ideally it would be near a drain and our drain is in a closet area along side the air handler. If I move it outside the closet its noisy as heck. In either place it runs almost non stop with the compressor kicking on and off every few minutes. Reasearch has show thats how these newer models operate. BTW, The wife does wash down there and also hang some out to dry. Humidity levels appear to differ as much as 8% depending on where I check them in the basement...its not consistent.

Does anyone have any experience putting a return from their heat pump / ac system in down there. To what degree will it lower humidity? I am planning on getting the hvac guys out. Our system is about 4 years old. They said they'd come back and pop a few more vents in down there...to help with heat in the winter...but I am now wondering if a return would help with humidity and/or if there is a downside to adding a return.

Comments (8)

worthy
10 years ago
To reduce the noise, you could place the stand-alone dehumidifier in a separate closet and integrate it with the central fan supply ventilation, as described in Building Science Corp. document RR-OO5. All basements should have a return and most especially finished ones.
bus_driver
10 years ago
I have used several different makes and models of dehumidifiers. Most of them were noisy and several were short lived-- less than 2 years.
My most recent purchase is the Frigidaire FAD740DUD. Much quieter than any other I have owned and apparently much more efficient as it keeps the humidity level as set with much less running. Cost about $240 delivered to my house.
If your situation was in my house, I would buy one of the Frigidaire to try and then if I was pleased with it, buy additional units to place in other parts of the basement. I have two dehumidifiers in my basement.
Not sure if it will be significant on my power bill, but the sharply reduced running time should help reduce the running cost. I think my old unit was just not doing much moisture removal at the last.

This post was edited by bus_driver on Sat, Jun 8, 13 at 12:19
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Mossonarock
10 years ago
Lucky you! Only 60% humidity!
I struggle with getting my basement under 90%.
Even the concrete floor molds. Although, it has been raining a lot. Putting a return vent into your basement should help to vent fresh air down there, but what's the humidity like in your living space? If the humidity is about the same, putting a return vent in your basement won't bring down the humidity all that much. bus-driver, thanks for the recommendation for the dehumidifier. I believe I may need to consider that.
worthy
10 years ago
Sorry, but putting a return air in the basement without understanding supply and exhaust flows peculiar to your house could actually endanger your life unless your furnace and water heater are sealed systems or electric.

A properly designed return air ensures there is sufficient supply to keep the furnace operating without creating a negative pressure situation, either absolute or relative to other pressure. In any case, it is not the solution to basement high humidity.
andrelaplume2
Original Author
10 years ago
We have an electric heat pump.
bus_driver
10 years ago
Give us an up-date.
andrelaplume2
Original Author
10 years ago
Well, with the unit on high and set at 55%, I pretty much ignored. My little humidistat started showing less than 55% and I noticed the unit cycling though still running more than I'd like. I put the fan on low and its still maintaining 55% (assuming that's accurate) . Not sure if its more economical but its quieter. I guess at this point its all I can ask for. I have not tried setting it at 50%...maybe I should! I did put it back in the closet area....humidity rose to 60%...no dice in that location. I have not yet added a return.
bus_driver
10 years ago
What is your desired humidity level-- the "target" value? If 55, that is the perfect setting for that level. If you desire 50, what is the logic for using a different, higher, setting?