Wet windows on cold days in the morning

Steve Samperi

We have a problem I can't seem to figure out. When we wake up in the morning all the windows are wet. Now it doesn't happen every day, just certain days. My wife also has a few house plants that have been growing mold on top of the soil. We also have a skylight in the kitchen that the water just drips off.
Any help or advice would be greatly appreciated. THANKS!

Travis G.

humidifier

What kind of heat do you have?

paul lessard_2

could be products of combustion

have someone check out your equipment

Mark Eatherton1

I hope...

you have a CO detector in your home.

I have seen a direct corelation of humidity and spilled combustion products. This is not to say that you have a problem, but maybe you do.

It could also be something as simple as tight house syndrome.

Better safe than sorry. Waking up dead is not a good way to start the day. Call in a professional and have them check your home and gas fired appliances.

ME

Unknown

Need to know what

kind of heating you have and also what gas or oil equipment.

Moisture can come from a variety of causes. The one of greatest concern is caused by recirculation of products of combustion into the house. Products of combustion which should be exiting through flues or chimneys can get circulated into the house because of poor venting and ventilation. A tight house can cause a wet house syndrome or even worse Carbon Monoxide build up. The products of complete combustion are carbon dioxide, water VAPOR, and some nitrious oxides. The water VAPOR hitting cooler surfaces will condensate and give you the effect you are talking about.

I stongly suggest you have your house and heating system checked by a heating professional.

Aidan

condensation

The water vapour may not be from the combustion products. the air indoors will contain water vapour from breathing, cooking, washing, house-plants, etc..

If the windows are single glazed, or have metal frames, they will be close to the outside temperature. If this happens to be below the dew-point for the air indoors, then you get water condensing on the cold parts. Regular maintenance of oil or gas fired appliances is still good sense.

Tom Anderson

An Annual Occurance

There is a posting about this problem almost every year about this time on the Wall.

Heavy condensation occurs at windows and other thermal short-circuit points from interior moisture when the outside temperatures become cold.

We have the same problem every November and December here in our 30 year old house in northern Vermont, when the first real cold weather comes rolling in. All the double pane 70's vintage windows had puddles of water under them. The problem lasts for a week or two, then becomes less severe, and almost gone come very cold mid winter weather.

Assuming you do not have a combustion venting problem, the moisture is coming from materials in the house... woodwork, sheetrock, furniture, etc. which absorbed the moisture over the summer.

Moisture laden interior air must be replaced with much dryer outside air to reduce the overall RH inside the house. I'll bet the RH in your house is 40% or greater this time of year. Try running your bathroom exhaust fans continually in cold weather to help speed the ejection of the moist air. Run kithcen exhaust fans to eliminate new sources of moisture when cooking. This is one of the rare times when infiltration is beneficial for a few weeks.

Keeping a room warm reduces the quantity of condensation. Baseboard systems are especially nice for this since they directly heat the glass areas.

Hope this helps...

Dave Yates (PAH)

oddities in heating

We have a customer who lives in a 1,200 sq ft home that was experiencing the same problem. It's an older home with SP windows and not very well insulated. Hot air heating (newer 90+ unit we installed three years ago) with NO humidifier.

She's single and says she doesn't cook at home a great deal. She utilizes both a ducted hood over the stove and bath fan is ducted to the exterior too.

Had me scratching my head - right up until the moment I realized every room has about three dozen plants & some of those qualify as small trees! D'OH!

The humidity level hangs right about 45%. Any higher & she'd need to ventillate to prevent mold growth.

The comments regarding blocked flue are right on target though & that's the first thing I look for when arriving to service the heating. CO detectors are a wise investment. We promote their use on a daily basis.

A really smart CO detector manufacturer ought to set up a contractor coupon program whereby we could pass them on to customers. We're already in their house!

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

heretic

Normal

This is normal during transition to heating season, to some extent...

The 'stack effect' in the winter months dries the air, and all of the moisture-laden materials contained within the structure. Wood, concrete, fabrics, etc., all absorb moisture during warm weather. Concrete slabs and walls in particular hold very large quantities of water. Think of them like a sponge.

Entering into the heating season, the 'stack effect' really only gets going in the cold morning hours, during which the relative humidity is likely to spike, since there is so much excess moisture available within the structure. It takes prolonged periods of cold to get the structure dried out to winter equilibrium.

If you have a damp basement or slab already, that will make matters that much worse.

This is a good article on the subject:
http://www.homeenergy.org/archive/hem.dis.anl.gov/eehem/95/951108.html

To quote:
"Windows are typically the coldest surfaces in a room, and are therefore where moisture is most likely to condense. Condensation may occur either because the interior airborne moisture level is rising, or because the exterior air temperature (and the temperature of the interior surface of the glass) is dropping, so that the relative humidity adjacent to the window rises to 100%.

When condensation occurs, the window is acting as a dehumidifier for the room (unless the condensed moisture reevaporates). The more moisture generated in or entering a space, the more moisture will be deposited on the condensing surface. Vapor pressures will rise only when the rate of moisture generation or entry in a space exceeds the rate of moisture removal by the condensing surface. However, when moisture generation or entry stops or is reduced, equilibrium will occur at a vapor pressure limited by the temperature of the first condensing surface in the room. In effect, the temperature of this surface controls the behavior of moisture in the room."

Steve Eayrs

If its too high humidity, then thats what HRV's are all about. Exhaust the moist inside air, and replace it with the dryer outside air, which is preheated by the heat exchanger, with the air being exhausted.
Of course the flue gas leak, as others mentioned should definitely be checked out ASAP.

Steve