View Full Version : humidity control problems in new house
01-31-2005, 12:43 AM
Please help me!!! I built a new home in East TN and am having a terrible time with the humidity. In the summer, the clothes in my closets molded and the house felt very damp and uncomfortable. The humidity measured around 80%. The mildew was all over the house...on all three floors. Now that winter is here, the house is so dry we can hardly stand it. The humidity measured in the teens for a while but it stays mostly in the mid to upper 20's. We have a forced air natural gas furnace and central air conditioning. My HVAC man wants NOTHING to do with this problem. I have a mist humidifier on both main floor heating units. He doesn't want to put a humidifier on the attic unit because of freezing. We have about 6,000sf on the first and second floor and about 3,000 in the unfinished basement. The basement has not been finished yet due to the humudity problems. I think I might benefit from the Aprilaire 5000 for the high humidity problems but what do I do in the winter? How can I increase the humidity over and above the 2 humidifiers I already have? My new home has become a nightmare. Please help me!!!!!!!
01-31-2005, 06:37 AM
Sir,if you are having problem of high humidity in the summer and low humidity in the winter,then someone did not
do there job properly when it comes to sealing up the home.
I would be looking for leaks in the envelope,as well as appliance that gets it combustion air from inside of the home.
I say its time for a blower door test.
01-31-2005, 07:20 AM
Sounds like a drafty home with oversized AC.
The cold dry air infiltrating in to your home is drying it out.
Lots of humidity in the outdoor air in the summer.
As a homeowner I would definitely follow Simpleman's advice, get a blower door test. There are several other people on this board who understand this type of problem and I expect they will agree to that test.
Your HVAC guy may not have the most integrity in this case. Keep your records in case a lawsuit is appropriate. I think he is already worrying about that.
This is too important not to do.
Best of luck -- P.Student
01-31-2005, 01:00 PM
It seems like you'd need an enormous amount of infiltration and oversizing to get it this bad. I'd be suspicious of a major return leak and oversizing *in combination*.
01-31-2005, 01:35 PM
how will an Aprilaire 5000 help control the humidity?
01-31-2005, 06:13 PM
80% humidity??? thats way too high, I live in the south and that percentage of humidity is way too high. I agree with everyone you may have some infiltration and the system may be oversized. Did the HVAC contractor run a Manual J? will he give you a copy?
01-31-2005, 06:33 PM
Brand new houses sometimes have high humidity until the paint, drywall compound, concrete, lumber, etc. have time to dry out. 80% seems extremely high.
02-01-2005, 01:24 AM
Sorry...I meant to say that I wondered if an ULTRA-AIRE dehumidifier might fix the problem. The only things in the house that would require combustion air are 2 gas water heaters and the 2 furnace units...all of them in the unfinished basement. All appliances and the dryer are electric. I can't imagine where leaks would be coming from. The house is well constructed, had house wrap, top of the line windows, is all brick, and was insulated over and above usual values. What type of places would I look for air infiltration to cause all these problems? I have never noticed any areas that I thought had a draft or cool spot. Also, can you explain to me what a blower door test is and what it is supposed to show? If my units(an Amana 90 Air Command #CHA60TCC and #CHA36TCC) are too large, would it fix the problem if when I finished the basement, I ran the heat and air ducts off these units instead of a whole separate system, which is what is proposed? THANKS!!!
02-01-2005, 08:17 AM
first, YOU need to run the load calc program from this site -- you will have to know or measure the outside dimensions & opening sizes -- and how much and what type of insulation is where in the house.
get a relative humidity gage at the local reptile shop $10.
do lots of reading here and BUILDINGSCIENCE.com.
do you have ventilation INPUT piping?
are the joints and cracks of the ducts & plenums of the units sealed with mastic?
blower door testing is putting a blower into an exterior doorway and sucking air out, measuring the pressure difference between in and out, and knowing how much power the blower uses -- it checks for cracks in the envelope -- cracks around elec boxes, under baseboard, around doors & windows, around piping & cable (CATV & phone = SLOPPY installs, usually), holes between those outlets into the attic or basement, etc. Or, spend the $300 to seal these holes yourself & forget the test.
Blower door testing is to measure the AMOUNT of leakage in your house. It might cost a couple hundred dollars and I cannot see any reason you should not do that ASAP.
If you find a high value, then you have a decent explanation for your problem. More than likely that problem would be leakage in gross amounts, and easy to find and fix. If you don't find a high value then that rules out some causes of your problem, and you and your technician can look more efficiently for the real cause.
I have been happy with hygrometers sold by Wal-Mart for $15-20, they are digital and easy to read. I have bought a half dozen and placed them around the house. While they are cheapies, they are sufficient for your needs and reasonably accurate I think. You might find it easier to locate a Wal-Mart than a reptile store <g>.
The Thermastor Ultra-Aire is probably a great product and should be on your list of possible solutions. I have a different dehumidifier made by the same company and it has brought down my humidity about 10 points -- but I was starting from 60% max rather than 80%!! But it should be considered only *after* you have identified the real cause of your problem. If you had a leaky boat, would a bilge pump be the first thing you think about? Of course not.
I would like very much to hear with your next post, that you have engaged a competent technician to search hard for the cause of your house problems. You need professional help in person! Do it now for goodness sake.
Best of luck -- P.Student
[Edited by perpetual_student on 02-01-2005 at 10:35 AM]
02-01-2005, 10:19 AM
Large basements create lots of moisture curing. Poured walls are famous for this. A dehumidifyer will help untill all this concrete cures. The other recommendations about a blower door test and hvac sizing are also sound.
02-01-2005, 11:51 AM
Do you know if these systems are setup for fresh air from outside? If they are that may be your problem.
02-01-2005, 12:42 PM
Does humidifier turn on while Furnace is on?
During the summer while AC is On look at the humidifier to see
is on or off. there may be a control/wiring problem on the humidifier.
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