indoor humidity at 60%?


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Old 10-09-08, 02:59 PM
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indoor humidity at 60%?

We have a 3 year old stick built home on a concrete slab and live in southeast North Carolina near the coast.
We have a heat pump for a/c and heating.Heat pump is outside and exchange coil is in the attic, heated space is 1462 sq ft.
Lately with the a/c set on 76* our indoor humidity is around 60%-is this anything to worry about?
We have many drywall screwheads that blistering up the drywall and paint right above them.Some have done it several times after fixing them.Can high humidity cause this?
 
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Old 10-09-08, 04:39 PM
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Yes high RH can cause this. 60% is to high! Need to get this under 55% 50 would be better.
 
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Old 10-09-08, 04:42 PM
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How do we get it lower?
We used to live in upstate ny and had a portable dehumidifier in the basement.
We have no basement so how do they do it on a slab house with exchange coil in the attic?
 
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Old 10-09-08, 07:44 PM
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I am going to guess you are near Wilmington. In green grass states this time of year we call it a no load time. No cooling and no heating. There is not a good way to remove the RH except using a dehumidifier. One can be installed in your attic to do the whole home. http://www.thermastor.com/Ultra-Aire-65/
 
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Old 10-09-08, 09:04 PM
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Humidity should be between 35-55 year round. Higher than 55 tends to cause problems with condensation, mold/mildew, etc. When humidity is high, it is important to run dehumidifiers to reduce humidity and fans to improve air circulatation.
 
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Old 10-10-08, 04:48 AM
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We leave our ceiling fans running and the air has been on 80% of the time.
I am also having a cracking problem with my concrete slab foundation. I have at least 6 that are over 10 feet long and minimum 1/8 inch wide in several rooms that we discovered after removing the builder installed carpet.
Could that be contributing to the humidity problem?
Yes we live near Wilmington,NC.
I had a structural engineer come and look at the house already and I was told we have some problems.
We also have a high water table in this area, and high outdoor humidity.
 
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Old 10-10-08, 05:34 PM
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Yes the cracks could let in moisture.
 
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Old 10-10-08, 06:17 PM
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As Air said, the cracks can bring in the humidity.. Have them sealed off.

If your budget don't allow you to get a whole house dehumidifier, a stand alone unit can be used, and set it in your kitchen or most open area of the home.. Being that you don't have a basement, let the unit drip into the pan and once the pan is full it will shut down on it's own.
 
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Old 10-10-08, 08:18 PM
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humidity

What is happening with your sheetrock is not being caused by 60% humidity, it is being caused by movement in your house. This can either come from framing that has been improperly dried or from foundation movement. Because you have already stated that your slab is cracking quite a bit I would vote for foundation movement. Sealing up your house is one way to help your humidity situation, also make sure the ductwork in your attic is properly sealed. You can also slow the fan down in cooling made to artificially create longer run times to extract more moisture, just be careful that you keep a clean filter because especially at this time of year you can have a freeze up.
 
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Old 10-10-08, 08:40 PM
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How are you measuring your indoor humidity? I have seen the cheapo meters that will lie pretty badly, you may want to invest in a proper humidty measuring tool before moving forward with any retrofit operations.
With the proper monitoring equipment you can watch for certain household activities that raise the Humidity level such as showers with the exhaust fan NOT on (a easy fix there) anyway just a thought.
 
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Old 10-11-08, 03:42 PM
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I had the a/c company that installed the unit come check out the house and verify the humidity level. He said I had a leaking window, allowing outside humidity to be sucked in when the fan runs.
They are Silverline vinyl windows, builder is no help(already retained a lawyer)-I called Silverline and left a message Friday.
My Silverline vinyl patio door is out of square also.
 
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Old 10-15-08, 02:15 PM
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I don't think my windows are leaking, the draft he felt was coming from the air vent of the a/c system.
I bought a dehumidifier and the humidity is coming down.
Now I put my humidity meter up to the a/c vent when it's running and the humidity is the same as the room level 3 feet above the floor (53%), shouldn't the air coming out of the vents be less humid?
Can a bad coil be causing my high humidity?
 
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Old 10-15-08, 04:56 PM
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Do you have any neighbors nearby who you are friendly with, so you can go there to compare? That be interesting. To see if it is just YOUR house or your lifestyle, for example.
 
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Old 10-15-08, 05:35 PM
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Yeah, I can ask my neighbors, some of them have been complaining about mold problems.
It's just the two of us, no kids, we each take one shower a day running exhaust fan, no excessive indoor water use, don't cook much.
We both work so we are not home 24/7.
 
 

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