Cold Weather = High Humidity ... Help Needed!

[jdetray]

Hello!

We recently moved into a 1950's home with gas-fired forced air heat and central air. The house is a 2000 square foot ranch built on a slab. The HVAC ducts are built into the slab. The furnace is a modern unit -- just 2 or 3 years old. The windows are relatively new double-pane with wooden sashes.

We're located in northwestern Ohio. Now that cold weather is here, the humidity in the house is very high. All of the windows are "sweating," to the point where they are dripping onto the wooden sills. The house often feels cold and clammy, even when the air temperature is high.

My sister's nearby home, which is also built on a slab, has exactly the same humidity problem. Nearby homes with basements don't seem to have this problem.

Questions:
1. Is the fact that the HVAC ducts are built into the slab a contributing factor to the humidity problem? If so, what is it about this arrangement that causes the high humidity?
2. Are there other likely causes?
3. What the best way to remedy this problem? We have a small portable dehumidifier, but it is not up to the task. We can buy a bigger dehumidifier, but I would really like to find a solution that is quiet and does not involve emptying heavy containers of water several times a day.

I am physically handicapped, and emptying the containers is difficult for me. I need a no-hassle solution.

I'm accustomed to houses that are too dry in the winter. This is my first experience with one that is excessively humid during the cold months.

Thanks in advance,

Jeff

[GregH]

Jeff,

The cause of excess humidity in the home is that there is more moisture being generated than can leave the structure.

The most common cause of this is making a home tighter and more energy efficient without taking care of the ventilation side of it.
Your solution could be as simple as using the bathroom exhaust fan and/or range exhaust fan running continuously or as deluxe as an air/air heat exchanger.
Often just running the bathroom exhaust or the range fan for a full hour after you use them helps a lot.

I would suggest you also purchase a digital humidity/temperature guage so you can at least get a reasonably accurate reading of the levels in your home.

Any more q's, just ask.

[Ed Imeduc]

Just off hand not a lot you can do here, I dont think.
1950 dont think they put any V/B under the slab there. Many of the ducts at that time where put in with the cardboard tube type pipe. Have seen they come apart and let water and dirt in to the duct set up. Id try and work on the outside first. Good gutters ,down spouts away from the home. Out side ground a good slope away from the home..
lots of dehumidifiers you can run a hose from them. Or get small pump to pump the water out . Like we use on the AC units sometimes.


ED ;)

[jdetray]

Thanks Greg and Ed,

We are going to get the HVAC contractor for the house to come in and give us an evaluation. There are a lot of homes in this town of similar construction and age (slab foundation, built in 1950's), so they must have seen this problem before.

This is our first winter in this house, so the humidity problem caught us off guard. It's so bad that some comforters and blankets actually feel damp!

We sometimes don't run the bathroom exhaust fan at all after a shower, but we will certainly start doing that. The kitchen has no range hood, which I'm sure contributes to the humidity.

Just grasping at straws, what about an attic exhaust fan to promote good ventilation? Can these be controlled by a humidistat to operate when the humidity rises above a certain level? Or is that a stupid idea?

We'll attack this in multiple ways, I imagine, so I'm interested in learning what some of the practical steps might be.

- Jeff

[Ed Imeduc]

what about an attic exhaust fan to promote good ventilation? Can these be controlled by a humidistat to operate when the humidity rises above a certain level? Or is that a stupid idea?

Sure hope its not up there . Should have a V/B there at the ceiling and not let it up into the attic. Think of the attic as it's on it's own. You do want it to have all the vents it needs up there. If this humidity did get up in the insulation from the home it would like kill the R value of the insulation you have there. "I know been there and done that."

ED ;)