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Window Condensation

ced48
ced48 Member Posts: 469
in THE MAIN WALL
Well I put in a Modcon boiler which heats with 120 degree water, +- baseboard radiation, tightened house up with new windows, doors, and insulation. Great, nice low gas bill, but now I have an issue with condensation on the windows. I assume caused by low heating water temperature, and lack of air movement. Is an HRV unit going to solve my problem?

Comments

  • JUGHNE
    JUGHNE Member Posts: 11,276
    Sometime extended use of bath and kitchen exhaust fans by use of timers will clear it up. It has worked for me.
  • Robert_25
    Robert_25 Member Posts: 549
    Did you do other remodel work that added a bunch of moisture to the house?  Thinset and sheetrock compound contain a lot of water.  If you did a remodel and just closed up the house and turned the heat on, the condensation may clear up in a few days.  A dehumidifier may also help get things to a steady state.
  • ChrisJ
    ChrisJ Member Posts: 16,316
    You didn't give us enough information in my opinion.

    Is it all of the windows?

    What's the indoor RH and temperature?
    Whats the outdoor temperature?


    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

    Canuckerethicalpaul
  • ced48
    ced48 Member Posts: 469
    All windows, RH 50% +, outdoor temp 35 degrees and below.
  • Zman
    Zman Member Posts: 7,611
    I have found that crawlspaces with exposed dirt or basements with inadequate moisture/vapor barriers are often the culprit.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • ChrisJ
    ChrisJ Member Posts: 16,316
    50% is probably too high in the winter.  I've always heard 35% is safer.  I agree you need better exhaust fans and perhaps need to bring in some air in general.

    But I'm not sure I would expect good windows to condensate with it 35 degrees out either even at 50%?  That seems surprising.



    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

  • ced48
    ced48 Member Posts: 469
    Getting the humidity level down seems to be one of the issues, but when the humidity outside is even higher than inside, seems like a HRV system would be counter productive.
  • ChrisJ
    ChrisJ Member Posts: 16,316
    edited December 2020
    ced48 said:

    Getting the humidity level down seems to be one of the issues, but when the humidity outside is even higher than inside, seems like a HRV system would be counter productive.

    Depends on the outdoor temperature.

    80% RH at 30 degrees F is only 18% at 70F.
    100% RH at 0F is 6% at 70F.

    That's why it's relative humidity. This is also why the windows are condensing humidity. The air cannot hold as much humidity when it hits the cold glass so the water literally falls out of it.

    Here's an online calculator you can use to see the relation.

    http://www.dpcalc.org/

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

    ethicalpaul
  • ced48
    ced48 Member Posts: 469
    So, bringing in outside air with a temperature of 35 degrees and a relative humidity of 65% will actually decrease the the humidity level inside which is at 68 degrees and 50% humidity?
  • ChrisJ
    ChrisJ Member Posts: 16,316
    ced48 said:

    So, bringing in outside air with a temperature of 35 degrees and a relative humidity of 65% will actually decrease the the humidity level inside which is at 68 degrees and 50% humidity?

    Yep.

    This is why drafty houses like mine are dry in the winter. It has nothing to do with the type of heat (forced air vs steam vs hot water) etc. But forced air, especially if installed improperly can make infiltration worse.

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

    Canuckerethicalpaul
  • JUGHNE
    JUGHNE Member Posts: 11,276
    Perhaps a big factor in the OP's house is that he got rid of a chimney vented boiler and went ModCon, probably 2 pipes.
    The constant flow of basement air up the chimney caused dry outside air to be pulled inside from various places.
    Tightening up the house and losing that air flow would add to retaining inside humidity.

    Our house is "superinsulated" with vapor barrier everywhere, minimal exterior wall penetrations. We had to run bath fans maybe 30 minutes per use to prevent condensation on windows.
    We have a 6" cold air pipe hanging into the basement for fresh air. Now only with a full house on holidays, will we see moisture.
    But all the kids live with heat pumps and feel overheated with our 72-74 rooms, so windows are snuck open when they think I am not looking. So plenty of cold dry air coming in.
  • Jamie Hall
    Jamie Hall Member Posts: 24,857
    There's a bit of elementary physics involved here. If we suppose an interior air temperature of 70 F and an interior relative humidity of 50%, then you will get condensation on any surface cooler than 50 F. Which a window is very likely to be if it's 30 outside.

    This has nothing to do with the source of the heat which is maintaining the interior temperature (assuming it's not open water, of course -- nothing like a hot tub!).

    What happens is that if the house is made tight, the natural moisture from human occupancy and activity will often raise the relative humidity into the critical range -- or even higher. Older, draughtier, houses had much better indoor air quality and much lower humidity -- and didn't have the problem.

    An HRV (sensible, not latent) will help by bringing in more outside air and lowering the relative humidity -- but if you want high relative humidity, you will have to cope with the condensation.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • bburd
    bburd Member Posts: 1,041
    @op I don’t want to worry you unnecessarily, but one of the signs that the combustion fumes from a gas fired appliance are not properly vented to the outdoors is high humidity indoors. 

    Are you absolutely sure the exhaust from that modcon boiler is venting out of the house as it should? Carbon monoxide from an incorrectly vented gas fire can kill you, and you’ll never smell it.

    If you have working carbon monoxide (CO) detectors and they are not alarming, you are probably OK.
    —
    Bburd
  • pecmsg
    pecmsg Member Posts: 5,294
    bburd said:

    @op

    If you have working carbon monoxide (CO) detectors and they are not alarming, you are probably OK.

    CO Alarms that are UL 2034 listed are virtually worthless. They will only alarm when 70PPM is achieved or exceeded for between 60 & 240 minuets.

    Every home Should Have a Low Level Detector!
    https://www.myhomecomfort.org/carbon-monoxide-levels-risks/
  • ChrisJ
    ChrisJ Member Posts: 16,316
    edited December 2020
    pecmsg said:
    @op

    If you have working carbon monoxide (CO) detectors and they are not alarming, you are probably OK.
    CO Alarms that are UL 2034 listed are virtually worthless. They will only alarm when 70PPM is achieved or exceeded for between 60 & 240 minuets. Every home Should Have a Low Level Detector! https://www.myhomecomfort.org/carbon-monoxide-levels-risks/

    I've seen people in here say this repeatedly.
    If they are "virtually worthless" why is that the standard that was developed and agreed on?

    If that is worthless why do we feel other codes and laws are so important?  

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

    motoguy128EdTheHeaterMan
  • pecmsg
    pecmsg Member Posts: 5,294
    edited December 2020
    ChrisJ said:


    pecmsg said:

    bburd said:

    @op

    If you have working carbon monoxide (CO) detectors and they are not alarming, you are probably OK.

    CO Alarms that are UL 2034 listed are virtually worthless. They will only alarm when 70PPM is achieved or exceeded for between 60 & 240 minuets.

    Every home Should Have a Low Level Detector!
    https://www.myhomecomfort.org/carbon-monoxide-levels-risks/

    I've seen people in here say this repeatedly.
    If they are "virtually worthless" why is that the standard that was developed and agreed on?

    If that is worthless why do we feel other codes and laws are so important?

    That level was accepted to cut down on 911 calls!
    CODES and Laws are Minimum Standards
    HomerJSmith
  • ced48
    ced48 Member Posts: 469
    I have run a combustion analyzer, 0. Thanks for the tip.
    Zman
  • pecmsg
    pecmsg Member Posts: 5,294
    ced48 said:

    I have run a combustion analyzer, 0. Thanks for the tip.

    0 What?
  • ChrisJ
    ChrisJ Member Posts: 16,316
    edited December 2020
    pecmsg said:
    I have run a combustion analyzer, 0. Thanks for the tip.
    0 What?
    I'm going to go out on a limb and assume 0 ppm CO.  ;)

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

    CLamb
  • motoguy128
    motoguy128 Member Posts: 393
    I thought it was a time weighted average and lower levels around 10ppm over 8 hours will still trip the alarm. Where more toxic high level will trip it almost immediately. It’s to prevent nuisance trips form ovens and stoves, and keep the price reasonable to there’s widespread adoption of the devices.

    That’s my take.
  • pecmsg
    pecmsg Member Posts: 5,294
    motoguy128 said:
    I thought it was a time weighted average and lower levels around 10ppm over 8 hours will still trip the alarm. Where more toxic high level will trip it almost immediately. It’s to prevent nuisance trips form ovens and stoves, and keep the price reasonable to there’s widespread adoption of the devices. That’s my take.
    On the UL Listed CO Detectors? No
    69PPM NO zero alarms
    70PPM OR above 60 to 240 minutes before alarming. 
  • ChrisJ
    ChrisJ Member Posts: 16,316
    pecmsg said:
    motoguy128 said:
    I thought it was a time weighted average and lower levels around 10ppm over 8 hours will still trip the alarm. Where more toxic high level will trip it almost immediately. It’s to prevent nuisance trips form ovens and stoves, and keep the price reasonable to there’s widespread adoption of the devices. That’s my take.
    On the UL Listed CO Detectors? No
    69PPM NO zero alarms
    70PPM OR above 60 to 240 minutes before alarming. 
    They also detect a rapid rise in co.


    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

  • Jamie Hall
    Jamie Hall Member Posts: 24,857

    It would have been much better @Marcus_Rull , to start a new thread on this.

    However… a skylight is a window. It just happens to be in a roof. Whether or not you will get condensation on the inside of it depends on two things: the dewpoint of the air in the house and the temperature of the inner surface of the glass. The latter depends on how good the skylight is and the interior and exterior air temperatures.

    You can get condensation on a skylight — like any window. It is much more likely on cheaper skylights (like windows again — you get what you pay for, and quality insulating double or triple pane skylights are VERY expensive).

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • WMno57
    WMno57 Member Posts: 1,408

    Interesting that both Marcus Rull and John Piterson both use an underscore in their username.

    I wonder if they know each other?

    WMno57_didn't_fall_off_the_turnip_truck_yesterday

  • Erin Holohan Haskell
    Erin Holohan Haskell Member, Moderator, Administrator Posts: 2,354
    https://forum.heatinghelp.com/discussion/comment/1801710#Comment_1801710

    Both were spam accounts and I've removed them. Thanks!

    President
    HeatingHelp.com

    EdTheHeaterManWMno57ratio
  • jumper
    jumper Member Posts: 2,385

    First thing to try is a small fan. If it works she can try fans in any room where OP doesn't like condensation. Or try running baseboards @ 160° and see what happens. 50% R.H. dries up moisture if there's enough air circulation.

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