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Do You Have IR Thermometer

Post in 'DIY and General non-hearth advice' started by James04, Jan 28, 2009.

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  1. James04

    James04 Member

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    If you have one of the IR thermometers. I would like to ask you for a favor. I am having trouble with condensation on my second floor windows. This is what I have found.

    Typically the first floor of the house is in the mid to upper 70's with a RH (relative humidity of about 35%). This is with a pot of water on the stove. That is just about ideal. However the second floor will typically be in the low to upper 60's with an RH from 40 to 50%. So the cooling air raises the RH. That is not so bad. But I am getting lots of condensation on all of the windows of the second floor. These are new Pella windows. They are low E argon filled. They boast a U value of U.31. That is about as good as you can get without going to triple pain. So when I asked on another forum (machinists) what the problem may be one of the members advised that my windows may not be performing as advertised. So I took my IR thermometer upstairs and found that with a room temp of 70 the the Sheetrock near the windows was 69 and the majority of the glass was 61. I think that is about rite. However when you get to the the last half inch of glass at the bottom of the sash and the wood frame at the bottom of the sash it was 49. That is were the condensation is occurring. This is typical throughout the house only to varying temperatures. Depending on the temperature in the room.

    So I would like to ask anyone with an IR thermometer to take some reading like I described and report the results here. I am thinking these windows are either defective, over rated or I am expecting too much. The windows are installed properly and they do make a seal. There are no drafts. So before I call Pella. I would like to know if this is indeed normal or my windows are not performing as they should.

    Also My home is 2400 sqft colonial (1200per floor) new "tight" construction and well insulated. Do you think I am getting adequate heat up to the second floor? In other words rite now it is 77 on the first floor and 69 on the second floor. Does it sound like I am losing too much heat?

    I would like to hear about your experiance with these things. Do you have a big temperature differance between floors. Do you have condensation on your windows. Do you know what the RH is in your house. Any an al comments are welcomed and much appreciated.

    James

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  2. edthedawg

    edthedawg Minister of Fire

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    I live in the same area. I have a similar sized house. But mine is 124 years old "wheezing" construction. I've insulated a lot of it, but the 2nd floor joist bays are the big hurdle. Upstairs is COLD as as result. You sound like your temps are fine.

    My antique single-pane double-hung windows do tend to get a lot of condensation. I have a blanket hanging in front of our stained glass window and it's a freakin' waterfall behind it. I've had ice 1/4" thick on some single-panes before in rooms where the heat is off.

    I have replaced 14 of the windows (about half the house - all in the front, facing east and south, 6 downstairs and 8 upstairs) with the best Pella low-e double-pane replacement windows I could get. Al-clad, solid wood, yadda yadda. I never get condensation on those. Had 'em for years.

    That said, I don't suspect your windows as-mfg'd. I suspect the installation. The rough openings in the framing are likely shimmed and that creates a little air gap. If that's not filled w/ foam or fiberglass, it'll cool off the window locally w/ the temps we're having...

    I do have an IR thermometer - i'll take some readings tonight (hopefully I remember).
  3. James04

    James04 Member

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    Loc:
    Eastern Ct
    Hi Ed,

    Thanks for the reply. The windows were installed properly by me. I have installed more windows than I would have ever liked to. I was a carpenter for most of my adult life. The windows are fully insulated with low expansion foam all the way around.

    I would appreciate it very much if you could take the measurements that I have. Since we live in the same are perhaps I can take mine tonight as well and compare notes. Do you know if your windows are the proline? Those are what I have. They have the narrow wood sash frames about an inch and a half wide.

    James
  4. velvetfoot

    velvetfoot Minister of Fire

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    I have Pella windows on a 4 year old house and they have some condensation on them when it gets cold.
    I just got some readings of 56 and 40.
    That is on a window with a cellular shade on it that I lifted up.
    Sometimes if the shade is down all the way for a while, it'll get some condensation too.
    Lifting the shade a little on the bottom gets enough warm air on it to get rid of the frost.
    I recall I was surprised when we first moved to the house about three years ago at the amount of condensation I got on them.
    I don't know, but I might not be seeing as much as I used to.
    A friend at work had a similar issue with his Pella windows.
    They'll say that your house is too humid.
    I bet your pot of water doesn't help.
    I don't think we had this on our last house. It doesn't seem to have to get as cold in this house before condensation occurs, but it's subjective in my case.
    Perhaps it's something in the window design, like the hollow plastic channels the panes slide in channeling cold air.
    Maybe do a web search. I haven't yet.
  5. James04

    James04 Member

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    Loc:
    Eastern Ct
    Pyro,

    Thank you for taking those measurements. Are the two temps the pane and the edge of the bottom of the pane? Do you know which Pella windows you have? Are they wood frames? Also do you know the temperature in the room and the outside temp at the time?

    James
  6. Corey

    Corey Minister of Fire

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    It may not matter as much how the windows are performing, but what is in front of them. Even a high performance window will get cold if it has a big, heavy curtain/blind in front of it. When the window cools, you'll get water condensation as soon as the surface temp goes below the dew point of the air in the room. The solution is either to dry out the air or heat up the window. Most people object to "cracklin' dry air" during the winter - so that only leaves warming up the window. Basically, you'll have to open up any curtains or blinds and provide for enough airflow to keep the window warm. This is where the high performance comes in...you can keep the inside of the window warm, while the outside is cool - without loosing too much heat from the house. Of course, at some point, the outside temp may get so cold that the indoor temp can't keep the window above the dew point. But opening curtains, blinds and providing airflow would be the first step.
  7. velvetfoot

    velvetfoot Minister of Fire

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    James,

    It's not Pyro, that's what the forum software calls you depending on how many posts you have.

    I think I have a window that has the word 'architect' in it.
    It is wood with aluminum shield on the outside.
    Yes the two temps are as you described, but I got the same temp on all the sealing edges.
    The room with the window in it was about 71F.
    The window was next to the stove.
    It was about 27F outside at the time.


    In some rooms I have the cellular shades down all the way most of the time, and I check them periodically for condensation.

    I have some a couple of fixed double pane windows with definite condensation issues and have to make sure to keep the shades cracked there during the day.
  8. James04

    James04 Member

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    Loc:
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    Sorry Velvetfoot,

    Thanks again. I found some posts on ask the builder web site. It appears that the Pella windows in particular are having problems with condensation due to the aluminum spacer between the panes of glass conducting the cold into the sash frames. I feel like I paid for a quality brand name window and got stuck with junk. I have been told that other manufacturers are using a thermal break to avoid this.

    Corey,

    This was happening before I even put up curtains. Yes the curtains make it worse. I saw on ask the builder that the host recommends below 35% humidity for outdoor temps below 20F. That is pretty dry. I wonder if his opinion is that recommended by the window manufacturers. After someone has to sponsor the site.

    James
  9. velvetfoot

    velvetfoot Minister of Fire

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    That's very interesting info James.
    I'm having difficulty visualizing this.
    Do you have a link you can refer me to where this is discussed?
    Is this the spacer that Pella uses so they can make up the window with flat pieces of glass?
    In the old days Anderson used to use fused glass, but it wasn't as big a space between the two pieces.
  10. James04

    James04 Member

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