venting basement with dirt floor

Hi, The basement of our homeowner association community house is unfinished and has a dirt floor. We've already put down continuous heavy plastic, but th e humidity is still significant and anything we store down there made of wo od (or paper) grows mold. We don't have financial ability to properly wate rproof, pour concrete slab, etc. for another couple of years. I was thinki ng of installing a vent fan in one of the several open crawlspace vents to suck air out of the basement, acknowledging there may be rainy days where i t might be more humid outside than inside. My concern is outdoor temperatu re. We're in New York State. I don't want to create a negative pressure a nd draw cold air in if the outdoor temp is less than, say, 40F as it would risk freezing pipes elsewhere in the basement. Can anyone recommend a vent fan controller that would turn off at a low temp? I only see vent control lers that turn on/off at higher temps... like in an attic. Many thanks Theodore
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On Sunday, September 10, 2017 at 11:56:40 PM UTC-4, snipped-for-privacy@yahoo.com wrot e:

nd has a dirt floor. We've already put down continuous heavy plastic, but the humidity is still significant and anything we store down there made of wood (or paper) grows mold. We don't have financial ability to properly wa terproof, pour concrete slab, etc. for another couple of years. I was thin king of installing a vent fan in one of the several open crawlspace vents t o suck air out of the basement, acknowledging there may be rainy days where it might be more humid outside than inside. My concern is outdoor tempera ture. We're in New York State. I don't want to create a negative pressure and draw cold air in if the outdoor temp is less than, say, 40F as it woul d risk freezing pipes elsewhere in the basement. Can anyone recommend a ve nt fan controller that would turn off at a low temp? I only see vent contr ollers that turn on/off at higher temps... like in an attic.

An AC line thermostat used for electric resistance heating? IDK how low they go, but probably to at least 45 which would be low enough. I'd probably put it on a timer too. How well it will work, IDK. I'd be concerned about when there is a rapid temp change, it's cool inside and you pump humid outside air in. It's more days than just rainy conditions. I guess the fan will also equalize the temp, so maybe it will work OK. I'd proceed cautiously if there is stuff stored down there that belongs to other people, etc. If it gets wrecked after you install the fan, they may come after the condo association. No condo reserves to pay for fixing it right now, raising the fees a bit to pay it back to the reserves?
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Right... that's the other concern: drawing in 90F humid air in July when it 's a cool 75F in the basement will cause even more condensation. So I'd ha ve to have a sensor that measures/accounts for relative humidity too!? May be getting complicated. But, all opinions greatly appreciated.
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On Monday, September 11, 2017 at 10:29:49 AM UTC-4, snipped-for-privacy@yahoo.com wrot e:

it's a cool 75F in the basement will cause even more condensation. So I'd have to have a sensor that measures/accounts for relative humidity too!? M aybe getting complicated. But, all opinions greatly appreciated.
You could wire in a humidistat in series too that would respond to outside humidity. I could rig up something for my own house fairly easy. For a condo, you'd probably need an electrician.
If you want to respond to both outside humidity and temperature, I'd go with a relay system. Plug the fan into a receptacle controlled by a relay, use low voltage to control the relay. For a relay, google "relay in a box". Then you just need low voltage temp and humidity sensors, one that will close when temp is above a set point, the other that will close when humidity is below a set point and a 24V transformer.
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snipped-for-privacy@yahoo.com posted for all of us...

suck air out of the basement, acknowledging there may be rainy days where it might be more humid outside than inside. My concern is outdoor temperature. We're in New York State. I don't want to create a negative pressure and draw cold air in if the outdoor temp is less than, say, 40F as it would risk freezing pipes elsewhere in the basement. Can anyone recommend a vent fan controller that would turn off at a low temp? I only see vent controllers that turn on/off at higher temps... like in an attic.

I'm more concerned the association doesn't have enough money. What happens when an emergency occurs? What & where is this?
--
Tekkie

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