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  1. #1

    Very Dry home - help with bypass humidifier

    Hello (first post),

    I have a Honeywell bypass humidifier that is doing a poor job for my 4000sq ft (total w/finished bsmt) home (built in 2003). The humidity is < 20% but by hygrometer(?) does not read below 20%. I have read various posts and have come to 2 possible solutions.
    1) Try adding a duct fan to the bypass humidifier duct to increase air flow.
    2) Step up to a Aprilaire steam humidifier.

    For 1), I will try this first but wonder if I should continually run the duct fan or cycle it with the furnace. If I continually run it, I guess I should also continually run water across the humidifier pad?

    Thanks in advance and great forum.

  2. #2
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,547
    Perhaps, a wiser idea would be to determine the reason for the low humidity in the first place.

    Often, lower humidity is the result of cold, dry outside air leaking into the building, lowering humidity.

  3. #3
    Join Date
    Jan 2005
    Location
    Littleton, CO
    Posts
    264
    The bypass that I have installed at my home only maintains about 20% RH. I installed a trusteam at my parents and they can get about 40%. The downside to the steam unit, it will increase your power bill which depends on what level of humidity you want to maintain. I run my furnace fan 24/7 to constantly filter the air and the humidifier turns on and off depending on the RH in the return air duct. I have is wired to the fan and not when the heating calls. Good luck.
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  4. #4
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,047
    I've never been a fan of steam. Too much trouble. I put a small Truesteam in a condo which really needed little humidity and they didn't notice much difference. Glad it wasn't my idea. Been has it right. If you are that dry, you need to stop the infiltration.

  5. #5
    Quote Originally Posted by NoviceMan View Post
    Hello (first post),

    I have a Honeywell bypass humidifier that is doing a poor job for my 4000sq ft (total w/finished bsmt) home (built in 2003). The humidity is < 20% but by hygrometer(?) does not read below 20%. I have read various posts and have come to 2 possible solutions.
    1) Try adding a duct fan to the bypass humidifier duct to increase air flow.
    2) Step up to a Aprilaire steam humidifier.

    For 1), I will try this first but wonder if I should continually run the duct fan or cycle it with the furnace. If I continually run it, I guess I should also continually run water across the humidifier pad?

    Thanks in advance and great forum.
    My contractor has put in 2 8" ducts for fresh air into the enclosed utility room (Furnace + WH). Living in Colorado is very dry so I would believe this is the issue. I may have to look up code but I suspect this is overkill. If I could diminish this incoming flow, perhaps that is the best solution.

  6. #6
    Join Date
    May 2012
    Location
    Upper Michigan
    Posts
    3,588
    Quote Originally Posted by NoviceMan View Post
    My contractor has put in 2 8" ducts for fresh air into the enclosed utility room (Furnace + WH). Living in Colorado is very dry so I would believe this is the issue. I may have to look up code but I suspect this is overkill. If I could diminish this incoming flow, perhaps that is the best solution.
    How many btu total? You can also put a motorized damper on the pipes, on a call for heat it would open them.

  7. #7
    Quote Originally Posted by Joehvac25 View Post
    How many btu total? You can also put a motorized damper on the pipes, on a call for heat it would open them.
    The furnace is 132K (input) / 107K (output). The water heater has an insulating cover on it but it is 50gal capacity (if that helps). From google, it looks like a standard 50gal WH is 40K. So I guess my total would be 172K? Can this be converted to combustable air requirements?

  8. #8
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,875
    Is the air filter internal or external to the furnace. if external is there a door on the filter rack. Have motorized dampers installed on the intakes.

    A bypass humidifier usually has 150 CFM+/- going through it, so a booster fan is not needed. Connecting it to the hot water line will help some.
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  9. #9
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,619
    if the pipes are combustion air they need to be left open ,if they are fresh are they can be closed .im thinking that you have a high pipe and low pipe for combustion air not fresh air
    We really need change now

  10. #10
    Join Date
    Jun 2007
    Location
    Greenwood Indiana (Indianapolis)
    Posts
    420
    Honeywell humidistats are not accurate, turn it to max. for a test. make sure the water flow is good and floods the pad. I wire humidifiers so that its able to run when blower is on, not just when the burners are on. I never have had to add a duct booster to a bypass pipe, that don't seem logical.
    As iron sharpens iron so one man sharpens another Proverbs 27:17 NIV84

  11. #11
    Join Date
    Jun 2007
    Location
    Greenwood Indiana (Indianapolis)
    Posts
    420
    Quote Originally Posted by BaldLoonie View Post
    I've never been a fan of steam. Too much trouble. I put a small Truesteam in a condo which really needed little humidity and they didn't notice much difference. Glad it wasn't my idea. Been has it right. If you are that dry, you need to stop the infiltration.
    Next time try the Aprilaire steam, completely different technology and they kick *** I think its a model 800, They can be wired to 120v or 240v.
    As iron sharpens iron so one man sharpens another Proverbs 27:17 NIV84

  12. #12
    From what I have read so far,
    1) The two 8" ducts are for combustion air and cannot be altered
    2) The low humidity is probably due to air leakage. However, I would expect my home is pretty tight. The biggest leak is the combustion air. My basement is finished (with ceiling tiles) so I am not sure where I would check for leaks.

    I will try running the the humidifier 24/7 and wire the humidifier water into the furnace fan. If that does not solve it, I will look into the Aprilaire steamer.

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