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  1. #1
    Join Date
    Feb 2010
    Location
    Seattle, Wa
    Posts
    6

    Confused Removing high humidy issues

    Iv'e been fighting this present issue for a year now with no results from my prior havc instructor and hvac co workers. I live in seattle, wa in a 1700 sq ft rambler with an underground fully finished basement ( drop ceiling). My wife and I and my 2 kids occupy it about it about 14 hrs out of the day. I have 2 baths on the top floor and 1 in the basement, all have high cfm EH fans which are used. The bath down is plumbed to an in ground sump and ejected into the mainline. (main sewer line is higer than the lower bath). The house is a 1947 which I fully remolded - with double pane insulated windows and min r-30+ in the attic with code roof vents. Heating is an 80% 70kbtu gas furnace and 2.5 ton condenser.

    Last year my wife calls me at work and says there is some water in the mechanical room comming from the hot water heater. I had her turn off the water main comming in the house , which is located down stairs in the drop ceiling until I got home. I found the newer supply line had broke and replaced it. When turning the main back on I noticed a green stain line which ran down the wall where the shutoff is located. I also noticed all the copper which was insulated fully condensing. I removed all the insulation, wipped all the piping and checked for leaks, both with the water meter on and off- no leaks. Mind you this is in the wineter months here with alot of rain. I put the basement in 10 years ago which has a continous footing drain and has never leaked. I bought a portable 35 pint dehuhidifier and attempted to investigate further. I replaced the sump gasket, replaced all 3 closet rings on the toilets. The dehumidifier has run constantly both during the winter and summer for the last year. I run my ac from may to oct also. Humidity is 55-60 all the time regardless if I run the unit in auto or on. Like stated before the house is pretty insulated and tight. I don't pull in any make up air, since majority of the months the ouside is raining and don't want additional humidification brought in.

    Any ideas that can be brought to light would be much appreciated.

  2. #2
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
    Posts
    2,479
    It sound like a whole house dehumidifier is in your future. I don't see them much in our area. probably because of the cost, but I have installed them for people with the problem similar to yours.

  3. #3
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,062
    Quote Originally Posted by osci View Post
    Iv'e

    The dehumidifier has run constantly both during the winter and summer for the last year. I run my ac from may to oct also. Humidity is 55-60 all the time regardless if I run the unit in auto or on. Like stated before the house is pretty insulated and tight. I don't pull in any make up air, since majority of the months the ouside is raining and don't want additional humidification brought in.

    Any ideas that can be brought to light would be much appreciated.
    You have choices. Homes need fresh air change to be healthy. Most suggest an air change in 4-5 hours when the home is occupied. Air change purges indoor pollutants and renews oxygen. When the outdoor dew points are below 55^F, fresh dry air change removes moisture from the occupants and structural moisture. Seattle has low outdoor dew points during the winter months. Unfortunately, during the warmer months, fresh air outdoor air has higher dew points some of the time. At 70^F, 50%RH inside the dew point is 50^F. Therefore, the moisture from the outside infiltrating/ventilation air and the moisture from the occupants should be removed to maintain <50RH. You may need from 1-3 lbs. per hour of dehumidification when the outdoor dew points are above 50^F. Most residiential dehus are very slow at these low temps and <50%RH. I would fix the fresh air ventilation and dehumidification with one unit like the Ultra-Aire 70H. Fresh air ventilation during winter will take care of the moisture as long as you maintain +68^F inside the space. During wet times of the year, the Ultra-Aire will remove upto 50-60 pints per day. Ultra-Aire.com will show the concept.
    Look forward to further discussion. Keep us posted.
    Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  4. #4
    Join Date
    Dec 2000
    Location
    Flat Rock, NC
    Posts
    463
    agree that a ducted whole house dehumidifier is the best solution.

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