Windows Sweating?????

[Coach1310]

A buddy of mine is having an issue with sweaty windows. He just resided his house late this summer. It was due to the storm, like many others in our area. Anyway, he didn't replace any windows and I think he added Tyvek, but I am not sure. Is there anything he can do to eliminate the sweating/moisture problem?? Thanks I know he will appreciate any help.

[sweept]

They need to lower the humidity in there home. Also running the furnace fan continuiosly will help some. The colder it gets the lower the humidity will have to be.

[Roofer]

Yes, too humid.

How old is the home?

If it was just re-sided, they better have used tyvek, as it is code.

Tyvek alone could not cause sweaty windows. It is normally just too humid or the windows have lost their seal. Re-sisding would not cause this either, unless they used some type of sealed siding, like cement.

[stick]

I have battled this too, and I was told to watch the humidity since when it gets colder, the humidity (even at 30%) will start condensing. If there is an air to air exchanger, those settings can factor in too.

[Surface Tension]

Start out by knowing what the humidity is in the home.

You can get a Digital readout thermometer/humidity meter for 5 bucks.

Moister on windows. Warm moist inside the home hits a cold surface and condenses. Theres two variables here.

How moist that air is and how cold the surface is. You can reduce the the moister in the air and you can reduce that cold surface. That'll give less condensation on the window.

Come winter its not the furnace that dries out your house.

Winter: The colder the air the less moister it can hold.

Summer: Warm air can hold a lot of moister.

So unless your introducing the house with large amounts of moister your house should start to dry this time of year.

Where can you reduce moister now. Showers and baths put large amounts of moister in the home. Boiling water in the kitchen puts large amounts of moister in the home. Your raising the humidity in those rooms.

Reduce that by using an exhaust fan in the bathroom and hopefully you have a range hood thats vented outside.

Lets say your humidity is down around 30% now but still getting condensation on the glass. You've reduced the humidity level, so that means your glass is cold. I'll bet you don't have at least double pane windows and I'll bet you don't have a decent storm window, both of which would give enough insulating qualities to the point of stopping condensation at 30% humidity level. Get yourself the plastic wrap and you'll stop the condensation and save yourself money in heating dollars.

Lets say that humidity at 30% is condensing around the edges of the windows. In that case cold is being transfered from the sash. Most likely a vinyl sash with poor R value.

Next you can get condensation in areas where weather striping is failing or in some cases no weather striping.

As we get further into winter and colder temps the outside air will become drier. Your humidity level inside the home should be going down as well. With those colder temps the windows will get colder. You might start to see condensation then, its just a matter how good your window is. However with the lower humidity it might even out.

[reddog]

Anything you do to change the dynamics of a house, can have an effect on how the house functions. Sometimes, its as negative as the positive you were trying to gain.

Adding tyvek to the exterior wall assembly should reduce the wind movement through the structure ( if it does what it says it does), therefore the house may not be aspirating/breathing as well as it did prior to the housewrap/siding retrofit.

If its not naturally changing the air like it was prior to the retrofit, then, the humidity level will rise in the house, because its not breathing like it was prior. Tyvek will not cause condensation on windows, that is correct, BUT, adding tyvek to your home, can cause the house to carry more humidiity than the windows are capable of handling, when they did before.

Changing a furnace or water heater out, can have negative effects on how a house operates, as usually this takes a naturally aspirating appliance, and changes it to a sealed combustion unit, and the chimneys are eliminated. Chimneys ventilate a house 24/7 when the is a large enough delta T (temperature differential) through stack effect.

Two fixes:

decrease humidity in the house, by either a lifestyle change dehumidifyer, running the bath fans more often, central exhaust system or simply adjusting the heat exchanger to exhaust more, if there is one. A last resort to dumping the humidity level in a hurry, is to simply flush the complete air in the house, by opening the doors and windows on each end for a few minutes, and let nature take it course. While this may seem counterproductive, it is not quite as bad as it seems. First off, you are not dumping all the heat in the home, just the air. All of the walls, furniture and other things will maintain room temp during the flush, which is just for a few minutes. The other thing is, its considerably easier for your heating system to warm the new,dry air back up to room temperature, than it is to maintain temperature of moisture laden air.

OR, warm the surface of the windows, by leaving the drapes open, running the furnace fan (as mentioned earlier) or whatever you can do to keep the condensing surface warmer will prevent condensation, but its more cost effective to reduce the humidity level.

What you also need to realize, is that the windows are also a barometer of what is happening within the structure in other places. If the moisture level is high enough to condense on the windows, its condensing in other places within the structure that you cannot see. Most notably, rim joist areas, and possibly roof sheathing. While I dont think that the temperatures have been inclement enough for these areas to even start to show yet, it will happen, as the winter progresses, and you should keep an eye on them. Water does not like to be in a vapor state. It wants to be solid, whether thats water or ice. It will find the first condensing surface, whether its your windows, roof sheathing,rim joist, or your cocktail glass.

[Bjjams]

Is sweating on the windows an indication that I need to turn up the air exchanger? I've been turning it up slowly every couple of days, but I'm still seeing condensation mostly in the mornings only. Would it be more important to turn the air exchanger up or leave the fan on the furnace running?

[reddog]

If you are only noticing condensation in the mornings, and it has dissipated with the warmer daytime temps, I wouldnt make any adjustment at this time, unless you are getting water damage to the sills and sashes when it melts. Typically, this type of condensation will turn to vapor, rather than water, and not damage the windows. If there is damage occuring, then, you need to crank the system up, or boost it, if you can with the bath switches.

Are you able to boost your system temporarily in the baths at the time of showers? If so, run the system on high speed for at least an hour after showering. This can provide help, instead of cycling the complete system more often, 24/7.

Under extreme temperature differentials, there may always be condensation on the glass, regardless of the setting of the Xchanger. There will be a point, between too much moisture, and drying the house down, to where its too dry for creature comfort. The recommended humidity levels in an energy efficient structure in a heating climate during the winter is about 20-25%. This should still provide a level of comfort, and not allow any considerable condensation on the glass, unless temps get extreme.

[Bjjams]

Quote:

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If you are only noticing condensation in the mornings, and it has dissipated with the warmer daytime temps, I wouldnt make any adjustment at this time, unless you are getting water damage to the sills and sashes when it melts.

Are you able to boost your system temporarily in the baths at the time of showers? If so, run the system on high speed for at least an hour after showering. This can provide help, instead of cycling the complete system more often, 24/7.

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I haven't noticed any condensation in the afternoon or evenings and most of the showers are in the morning so that makes sense. I just assumed if there's any condensation on the window I have a moisture issue.

In my bathroom I do have the flat switch for the exchanger but when I have tried to use it in the past the light blinks twice and the exchanger doesn't immediately turn on. I think I need to do some research on my air exchanger and find out if it's working properly. As far as I know though it might be working right. Thanks for the help reddog.

[TNFL]

The newer houses have to be wrapped with poly inside of the studs and ty-vek outside of the house. This causes litle air movement and should reduce heating costs. However, as stated earlier with little air movement humidity can build up. Therefore, newer homes are required to be installed with an air exchanger, which brings fresh air in and pumps old air out. However as the air is exiting & entering it is seperated by a bunch of plastic channels so the heat & cold sort of rub off on each other.

So, basically, if you have an Air exchanger, you need to run it at a higher level. If you don't have one you will need to occasionally open a window. Or run your furnace fan a lot, since all furnaces have a fresh air channel (big flex duct that feels cold, do not ever plug this) nearby to prevent CO2 poisoning.

[Coach1310]

Thanks for the responses. Here is some more follow up info... the house has tyvek on the outside, but no poly on the inside.... the house is heated with hot water baseboard heat, so no forced air anywhere.. he is still having the problem, although it has gotten a little better...any suggestions other than adjusting air exchanger(which doesn't exist).... thanks again

[reddog]

Quote:

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Thanks for the responses. Here is some more follow up info... the house has tyvek on the outside, but no poly on the inside.... the house is heated with hot water baseboard heat, so no forced air anywhere.. he is still having the problem, although it has gotten a little better...any suggestions other than adjusting air exchanger(which doesn't exist).... thanks again

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1)Run the bath fans longer, which will dehumidify.

3)Mechanically dehumidfy.

4) open the doors and windows for a few minutes before you leave for work, and "flush" the house of a large dose of humidity.

5) turn off the humidifyer, if he has one running.. OK, just a shot in the dark, there. hehehe

6) eliminate any other source of humidity in the house, such as excessive plants, or firewood stored in the basement and such.

7)If there is any crawlspace in the house, make sure there is a sealed ground cover intact.

[scaup]

I have a similiar situation. There are a lot of variables that have been mentioned. The key for me and your friend is that I have no duct work in my house. We have baseboard elctric and wood heat. Becuase of the way the air natuarally circulates in our house we have dead spots in our bedrooms. If we had duct work condensation on the bedroom windows would be and easy fix but as mentioned earlier we have no duct work. So I have done the following:

1. Install Ceiling fans in each bedroom and run them on low durring the day. This helps move the moist air out of the bedrooms and replace with less moist air from other rooms.

2. As mentioned earlier keep the blinds open. We close them when we need to but when we do it does not take long for the condensation to begin.

Unless I tare my basement apart and install duct work with an air exchanger there really is no fix. You just kinda manage the problem for a few months. It is a bit of a pain but then again the water next to my kids bed doesnt turn into ice like it did in my fathers day so I can deal with it.