Newly installed window dilemma

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Newly installed window dilemma

#1 Post by Makman »

I am reaching out to all of the experts who frequent this board. I did much research here and onther places on the web before I made an informed decision and had 11 Softlite Private Label replacement vinyl windows installed in my home. The windows have been in for 1 week and I am experiencing a interior condensation problem worse than I had with the old windows. Allow me to give the basics: Had 11 garbage vinyl Acorn new construction windows replaced with 11 Softlite triple-pane, low-e, argon-filled w/Super Spacer, foam-filled frame windows. The dealer/installer claimed that this was the best for the money. The previous Acorn windows had a bad interior condensation problem to the point that the condensation would collect on the sills and run down the wall onto the carpet. The windows were also covered with mold and all of the seals were shot and the panes fogged. My house is only 10 years old and it has vinyl siding. The installers cut away the old windows with a Sawzall alongside the J-channel leaving the old nailing fin in-place. They then wrapped PVC coated aluminum coil from behind the J-channel, across the J-channel (covering it), and then wrapped into the house and nailed to the sheetrock returns in the window cavity. The windows came with insulation packs for the outside of the frames (to fill the gap between the wall and the window). The installers did not put them in stating that the windows were tight enough in the opening and that the insulation packs were twisting and binding. Once the window was set and secured, they caulked the gaps inside and out with a high-grade silicone caulk (can't remember the name). Now the problem: Here in NJ we are having 50-70 degree days and 30-40 degree nights so windows get open during the day and the furnace comes on at night. My new windows have so much interior condenstion that I now wonder if I made a bad decision, or got ripped-off. The condensation is occuring on the bottom edges of the glass units and were the interior grids come to the edge of the glass. Most of the condensation appears to be coming from the interior caulk joint especially at the bottom sill. Touching the caulk joint it feels cold and damp. Just an FYI: my interior humidity is abot 48% and I have my furnace humidifier turned off. I called the installer and I feel he is back peddling. He says it is a temporary problem due to season change. I disagree especially with regard to the caulk joint condensation. He says 48% humidity is too high. I thought triple-pane, low-e, Super Spacer would rectify the original condensation problem as his sales talk suggested. He states that he doesn't think it's an installation problem and had the Softlite rep call me. The rep said that the condensation is a combination of seasonal change and high indoor humidity. He suggested that I go on the Web and read up about condensation. I found out that with 40 deg. outside and 70 deg. inside, the recommended indoor humidity should be no more than 40%. I also found a chart that shows that triple pane, low-e should not form condensation on the glass until 68% humidity (40 deg outside, 70 deg. inside). I think I'm getting a run around. However the Softlite rep is coming out on Thursday hopefully with the dealer/installer. The softlite rep also stated that some people use the insulation packs and others don't. I could not get him to commmit to whether or not they are required. He said he would talk to the dealer/installer. That is my story so I'm looking for any suggestions on how I should address this problem with the rep and dealer/installer and if anyone on this borad has had a similiar problem.

Thanks in advance.

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#2 Post by Oberon »

Relative humidity is the ratio of the amount of water vapor actually in the air compared to the maximum amount of water vapor the air can hold at that particular temperature (and pressure).
In simplest terms, it is a ratio of the air's water vapor content to its capacity:

Relative humidity is given as a percent.
So, air with a 50% relative humidity actually contains one-half the amount of water vapor it could hold.
Air with 25% relative humidity contains one quarter of the amount of water vapor it could hold.
Air with 100% relative humidity is said to be saturated because it is filled to capacity with vapor.
Increasing or decreasing the amount of water vapor in the air will cause the relative humidity to go up or down as a consequence.

Dew point temperature is the temperature the air must be cooled to for saturation (or dew) to occur.
In a nutshell, the surface temperature of your windows is below the dew point or saturation capacity of the air in your home. When water vapor in the air comes into contact with a surface whose temperature is lower than the dew point the water vapor will condense and moisture is the result.
The difference between air temperature and dew point can indicate whether the relative humidity is low or high, for example when the air temperature and dew point are far apart, the relative humidity is low; when they are close to the same value, the relative humidity is high. When the air temperature and dew point are equal, the relative humidity is 100%. ..makes sense?

You mentioned that your home has a 48% relative humidity, which is rather high for the inside of a home. I am curious how you know that it is 48%?

There is a standard measurement of the ability of a windows resistance to condensation. It is called CRF, which means Condensation Resistance Factor. Without going into formulas and all, windows are tested to condensation resistance with an internal air temperature of 70F and an external air temperature of 0F.
A number from 30 to 80 is then assigned to the window, with the higher the number the greater the ability to avoid condensation. Some manufacturers include this number on their NFRC labels and some do not.
A CFR rating of 35 is generally considered to be the minimum acceptable rating.

All this stuff isn’t really getting to the root of the problem, which is, how to control the moisture on the surface of your windows.
Two ways to do it. First, lower the indoor relative humidity, which will raise the dew point.
The second option is to warm the surface of the glass to a temperature above the dew point for the temperature and relative humidity in your home…which is the reason that you bought these windows for in the first place.
ALL windows will “sweat” if the indoor air has enough moisture and the window glass is cool enough – which is subject to the outdoor temperature and the make up and quality of the window.

Your installer has suggested that this problem may be seasonal. He may be correct. It is not uncommon for windows to sweat a little in the change of the season from summer to winter…and the problem that you report is also not unknown among window manufacturers.

It really is entirely possible that this problem will correct itself as the air becomes drier and winter sets in.
But, I would suggest that if you could lower your indoor relative humidity to 30%-35% that it would really help as well.

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#3 Post by E-Z »

Hey Oberon, all good stuff and very useful specially cause we are turning seasons. People have a misconception of energy efficient windows and condensation but i think the industry also has hidden behind the logics and roots of condensation like a poorly insulated home. Obviously in this case the house was well insulated so oops there goes that one. Do you have any links that we proffesionals can look at and learn to articulate the condensation issue and describe it in lament terms to our customers?


E-z Windows

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#4 Post by FenEx »

Sooo many variables... and Oberon did a top notch job of explaining the physics part of it. Without actually testing your house... I see a few clues just based on your statements. If the house is only 10 years old... chances are it has a vapor barrier on the exterior of the walls behind the siding and nothing at the ceiling. The 90's were also pretty BIG on "ROOF VENTILATION" as it "was" thought to help a home breathe and release unwanted moisture as the mold issues came into the medias... in fact, it made it worse. Now you have buttoned up your windows (holes) even tighter. Stack effect would be my guess... actually drawing in moisture like a straw.

I would venture a guess that the condensation you see on your windows is only in the mornings and more prevelant in certain rooms... and probably increasing with the colder weather. Where is the humidistat... an interior wall? Where is your furnace... is it in the basement... and if so... is your basement damp? Your registers are right below your windows right? Need more info.

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#5 Post by Makman »

Thanks to all for your replies. I have researched the all about condensation, "tight" houses, indoor air quality, etc. and you are all right on track with your reponses. I guess I am going to have to look into "loosening" up the house perhaps with a "energy recovery ventilator". Here are answers to some of the questions:
I am assuming relative humidity based on a Radio Shack hygrometer located in the living room. I am getting my hands on a sling psychrometer that will hopefully give a better reading. Front of house faces north. House does have a Tyvek vapor barrier in some spots under the siding while I have also seen spots under the siding with just construction paper. The house does have "roof" ventilation consisting of a ridge vent, soffit vents, 3 gable vents and a power ventilator (not running this time of year). House does have a finished basement and furnace/water heater are in mechanical room in basement. Basement has never been damp except for one or 2 places and that was minor. The basement walls are finished with 2'x4' studs, insulation, vapor barrier, sheetrock with a suspended ceiling and carpet/tile on floor. Heat registers are NOT under the windows. Condensation is happening on EVERY window replaced throughout house but not on an 2 year old Anderson sliding patio door with double-pane, low-e glass. Condenstaion is seen in the mornings after cool/cold nights (40's). Forced hot air furnace has a self draining, element type wicking humidifier that is OFF. Humidistat for the humidifier is on the return plenum. Hope this info helps. Maybe I should not have put in such energy efficient windows? Thanks again for all of your info-it is invaluable.

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#6 Post by Guy »

Makman, first off I would try and force the installaer to insulate around your frames. The only time we ever caulk is if the window is tight to a stuc. If there is an eighth of an inch it should be insulated and not caulked. I'm not a technical responding person in any way. So FenX and Oberon by far have me with their superior advice. I've always questioned why we get condensation in our newer homes today. I live in MN so I know cold and warm climate change. I also understand the tight house theory. The thing that boggles me more than anything is the Hair Dryer Theory on glass. You know when you took a shower and had to John Travolta your hair for the Disco in the day. Out came the blow dryer to take the moisture off the window. Now if your furnace kicked on why didn't the moisture disipate? You would figure the forced air would work in the same way. My only theory here is it's a home without an Air Exchanger. Here's a great way to figure it out. At night before you go to bed turn on a vented fan to the outside. Like a bathroom fan at the highest level in the house. Close and lock all the windows in your home except for one at a low level. Just open it a crack. Let the fan run through the night and see if you have condensation in the morning. Usually the cold air at night is low with humidity. So you will keep your level down as it draws colder air into your home. This will show you how tight your house is if it works. It would be interesting to hear the results from this.


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#7 Post by Oberon »

E-Z, I would suggest a google search of "windows condensation humidity" and I guarantee that there will be so many responses that you won't know where to start! But, within all that data will be the information that you are wanting. It will just be a matter of filtering it!

Hygrometers are certainly an acceptable way to measure humidity, but the sling psychrometer really is the best way to is not all uncommon to use a hand-held, manually operated, sling psychrometer to calibrate the fancy, and expensive, electronic measuring devices. Just be sure that there are no "objects" close by when you are spinning it! The thermometers on the psychrometer are breakable when they contact something while in motion (voice of experience here!)...and keep the thing away from your body, at arms length, as you spin it, otherwise it could read your personal humidity as well.

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