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  1. #1
    Join Date
    Oct 2005
    Location
    Barrie, ON
    Posts
    2
    Hi there,

    Trying to find a solution for excess humidity in the home. I am between a whole house dehumidifier, and a heat recovery ventilator. The house is always way too humid 70-80, and it won't come down in the winter, therefore the windows are covered with condensation.

    The units i've looked at are the venmar HRV, the aprilarie dehumidifier and the ultra aire dehumidifier.

    Any feedback is greatly appriciated.

    Thanks!

    Home Info
    Barrie, ON, CAN
    1200 sqft
    forced air

  2. #2
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,089
    In the winter, an HRV could be the answer using much less juice. But in the summer if you have humidity issues, I don't see them helping unless your area has no humidity with the heat. Most areas would be better served with a dehumidifier if object is year round humidity control. If the house is that tight, might need both.

  3. #3
    Join Date
    Apr 2002
    Posts
    11,808
    The dehumidifier is for summer time humidity problems, you will need the RH down below 40% most likely in the dead of winter, a dehumidifier will ice up.

    Ventilate the house in the heating season, use an HRV if you want to use minimal energy.
    The way we build has a greater impact on our comfort, energy consumption and IAQ than any HVAC system we install.

    http://www.ductstrap.com/

  4. #4
    Join Date
    Mar 2004
    Location
    Vancouver, BC
    Posts
    125

    Find the source of the humidity first

    Why is there "excess humidity" in the first place? An HRV will help for most of the time, but with the humidity levels you describe, it will ice up in the winter. The first step would be to track down the source of humidity and try to eliminate it first.

  5. #5
    Join Date
    Apr 2002
    Posts
    11,808
    There is a good chance that the source of humidity is the occupants of the home.
    The way we build has a greater impact on our comfort, energy consumption and IAQ than any HVAC system we install.

    http://www.ductstrap.com/

  6. #6
    Join Date
    Apr 2002
    Posts
    11,808
    The 70 to 80% right now could also be home giving off moisture from a warm humid summer, this high of a level should not persist much longer, however with winter temperatures you would be getting condensation from 40 to 60% RH on those windows with a well sealed home.

    gmcd is right about finding the moisture source-- avoid hang drying clothes in your basement.
    The way we build has a greater impact on our comfort, energy consumption and IAQ than any HVAC system we install.

    http://www.ductstrap.com/

  7. #7
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,371
    A home needs 50-75 cfm of fresh air to purge pollutants and replace consumed oxygen through the year regardless of outside weather. With outdoor temps. of 20^F 80%RH, 15^F dew point, 12 grains/lb. of air, 100 cfm(428#air/hour) of infiltration/exfiltration removes 8,132 gr.(1.2 lb) moisture/hour at 70^F, 28%, 34^F dp, 31 gr/# inside air. One lb./hour is typical moisture load for 4 people. Most homes air infiltrate/exfiltrate +100 cfm from wind and stack effect during cold weather through the high/low cracks and exhausting devices like clothes drier, kitchen hood, bath fans and heaters. When moisture loads are higher or air leak rates are lower, indoor dew points rise. The choices are to lower the indoor dew point or raise the temp of the cold condensing surfaces. Deep night t-stat setback or window curtains could be part of the cold glass problem. High ground water tables, exposed earth in basements/crawlspaces, fish tanks, many plants/pets, or high occupany increases the moisture load. If the only problem is air tightness, increasing the air leakage to 100 cfm is a simple solution. If the natural cold weather leakage is 50 cfm and exhaust devices are used, adding 75 cfm of makeup air will change the total ventilation to 100 during cold weather and 75 cfm during the rest of the year. Fresh air is a necessity all year for IAQ. The additional 50 cfm of ventilation cost $75 with NG heat at 8,000 degree days. Cut the cost in half with a HRV.

    With correct fresh air ventilation, when the outdoor dew point is above 55^F, dehumidification is a must to control indoor humidity. The Ultra-Aire APD is setup for make-up air ventilation for winter humidity control and dehumidification during the times of the year when ventilation does not provide humidity control in the home. For starters, operate the bath fans continuously and crack windows to remove enough moisture during cold weather to stop window sweating. Talk to us if the problem is not easy to resolve with a little extra ventilation. We have fixed many with same problem. TB

    Check your %RH meter with a cup with 2 tbsp salt + 1 tbsp water in a sealed container. Should read 75%RH after one hour. The %RH should drop 2% for every degree warmed by a hair drier.

    This a complete discusion of the problem.
    http://thermastor.com/pdf/winter_moisture.pdf

  8. #8
    Join Date
    Apr 2002
    Posts
    11,808
    Running fans steady with the windows cracked is a good experiment teddy. They could try that when it was 12C or colder up there.

    You need to brush up on your energy costs tho, and they are over 8000 degree days there.

    The dehumidifier would help them in the summer, I do not get the impression they have AC.


    [Edited by Carnak on 10-25-2005 at 02:49 PM]
    The way we build has a greater impact on our comfort, energy consumption and IAQ than any HVAC system we install.

    http://www.ductstrap.com/

  9. #9
    Join Date
    Feb 2005
    Location
    Barrie, Ontario
    Posts
    4,622
    Originally posted by ryebox
    Hi there,

    Trying to find a solution for excess humidity in the home. I am between a whole house dehumidifier, and a heat recovery ventilator. The house is always way too humid 70-80, and it won't come down in the winter, therefore the windows are covered with condensation.

    The units i've looked at are the venmar HRV, the aprilarie dehumidifier and the ultra aire dehumidifier.

    Any feedback is greatly appriciated.

    Thanks!

    Home Info
    Barrie, ON, CAN
    1200 sqft
    forced air
    As Mr. Carnak Sir has posted to my attention, your thread, I am in Barrie also and very conditioned to our weather. I also had exactly the same problem the winter I installed my Hi-eff furnace after removong an old standard.( I should have known better.) The following fall I had to install an HRV with a wall control(dehumidistat) and a fan start relay. If the house requires dehumidification the control will start the HRV and the furnace fan. I put the control on the wall of a hallway between two baths upstairs... This is great for us and works well... As it stand my humidifier is practically redundant...runs maybe once or twice a year.

    In our case the house isn't R2000 but is semi-tight. The old standard furnace continually used indoor air for combustion and by doing so replaced it with outside air thus lowering the humidity in the home. When I installed the new furnace, direct vented to the outdoors, I didn't take this into consideration and found that there was not enough air infiltrating the home. I had to add some.

    The question for you is only this...Do you have a hi-effeciency furnace with no means for air exchange? If you do, you probably require an HRV. As mentioned in the above posts and whole house humidifier is a summer item and extremely cost INefficient when you can use outside air at a fraction of the cost to do the same job.
    Is this a Fabreze moment? C.Y.D. I'm voting white elephant. 2.
    My competition are my best salespeople!

  10. #10
    Join Date
    Apr 2002
    Posts
    11,808
    Houses built in the 70s in Ontario were prime examples of an accident waiting to happen.

    They had natural draft furnaces with pilot lights. Over the years, the place was tightned up, weatherstripping improved, new windows added.

    Drafthood furnace ventilating home 24/7 in the winter.

    Then the furnace gets upgraded to something with induced draft and suddenly a condensation problem when there was never one before. Lost the 24/7 ventilation with the furnace upgrade. Have to upgrade ventialtion when you upgrade furnace.

    Houses built in 80s without HRVs had constant winter humidity problem. By 1990, codes were tightened up on residiential ventilation at least in NW Ontario that pretty much forced you to have an HRV if you had a B-Vent appliance. If you have a 90% furnace codes would allow ventilation without heat recovery, at least in NW Ontario.

    The way we build has a greater impact on our comfort, energy consumption and IAQ than any HVAC system we install.

    http://www.ductstrap.com/

  11. #11
    Join Date
    Oct 2005
    Location
    Barrie, ON
    Posts
    2
    Thanks everyone for the replies, more than I expected. Especially the gentelman from here in barrie, makes it easy to compare.. Going to go for the HRV as recommended.

    Thanks Again!

    Ryan

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