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  1. #1
    Join Date
    Jul 2006
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    206

    Which type of humidfier for Carrier Infinity -- bypass or fan powered?

    My humidity level has been at 25% during the cold spell we have had lately. So I'm considering a humidifer for my carrier infinity zoned system.

    Based on some airflow issues with the small basement zone (16%) -- compared to 43 and 34% for the bedroom and main floor zones; the HVAC contractor is recommending the fan powered humidifier.

    What are the pluses and minuses of fan powered vs. bypass humidifiers?

  2. #2
    Join Date
    Jul 2008
    Posts
    551
    What kind of outdoor temps were you seeing at your 25% humidity levels?

  3. #3
    Join Date
    Jan 2009
    Location
    Keokuk, IA
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    5,520
    A bypass siphons off some CFM from the overall blower output. Typically around 100CFM I believe, but possibly a little more. Bypasses are less expensive, don't need 120VAC power and the fan power comes form the more effecient ECM motor on the main furnace rather than a small stand-alone fan (not very significant, probably a 5 Watt difference). The Bypass units may tend to leak air more since they are pressurized (I'm adding some thin weather stripping to seal it a little better.

    The fan powered units have a higher output, especially when only running on a circulating fan when the heat isn't running. They most likely are a little more effecient with water useage.

    Personally, I'd get the fan powered unit. I'm probably going to upgrade to one in a few years time. That 100cfm you lose isn't so bad when it's a 8% loss at 1200CFM, but it's noticeable when you're on the low speed fan and you lose almost 20% of your airflow.

  4. #4
    Join Date
    Jul 2006
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    206
    Quote Originally Posted by badtlc View Post
    What kind of outdoor temps were you seeing at your 25% humidity levels?
    In the 20s. At night down to the teens.

  5. #5
    Join Date
    Jul 2006
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    206
    Quote Originally Posted by motoguy128 View Post
    A bypass siphons off some CFM from the overall blower output. Typically around 100CFM I believe, but possibly a little more. Bypasses are less expensive, don't need 120VAC power and the fan power comes form the more effecient ECM motor on the main furnace rather than a small stand-alone fan (not very significant, probably a 5 Watt difference). The Bypass units may tend to leak air more since they are pressurized (I'm adding some thin weather stripping to seal it a little better.

    The fan powered units have a higher output, especially when only running on a circulating fan when the heat isn't running. They most likely are a little more effecient with water useage.

    Personally, I'd get the fan powered unit. I'm probably going to upgrade to one in a few years time. That 100cfm you lose isn't so bad when it's a 8% loss at 1200CFM, but it's noticeable when you're on the low speed fan and you lose almost 20% of your airflow.
    So does that mean a fan powered unit can humidify even when the furnace itself is not running?

  6. #6
    Join Date
    Dec 2007
    Location
    Cedar Grove, Wi-Sheboygan
    Posts
    1,582
    Yes, you can have the humidifier set-up one of two ways, it can humidify while the furnace is calling for heat or you can have it run when ever there is a need for humidifcation. I run my fan on low 24/7 so I have my powered humidifer run when ever there is a call for humidification and have the hot water line tapped into the humidifer as well. Also depending on the tightness of your home will depend on the ability to hold a steady humidity level in your home. If you have a realitively tight home it shouldn't be too hard to maintain 35%-45% RH thru out the house, if you have a leaky home and ok windows oyu might find that having high humidity will cause you to have codensation problems on your windows. But IMO as well as most here will tell you that a powered humidifer is better than a by-pass or even a steam mist type humidifer. The powered unit will give you more humidity especially in a 2 story or large foot print ranch style dwelling.

  7. #7
    Join Date
    Jan 2009
    Posts
    386
    Quote Originally Posted by DanW13 View Post
    ...But IMO as well as most here will tell you that a powered humidifer is better than a by-pass or even a steam mist type humidifer....
    How is a powered humidifier better than a steam mist humidifier, such as a TrueSteam from Honeywell?

  8. #8
    Join Date
    Jan 2009
    Location
    Keokuk, IA
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    Quote Originally Posted by eap View Post
    So does that mean a fan powered unit can humidify even when the furnace itself is not running?
    No, you still need the furnace fan to ditribute the moisture added by the humidifier located on the supply pelnum (just above or next to the air handler).

    The infinity system however has a low speed continous fan. It's often best to just leave that running most times your home. They normally consume less than 80 Watts.

    The circulating fan itself should reditribute moisture somewhat between the zones.

  9. #9
    Join Date
    Jan 2009
    Location
    Keokuk, IA
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    Quote Originally Posted by skizot View Post
    How is a powered humidifier better than a steam mist humidifier, such as a TrueSteam from Honeywell?
    The truesteams are nice, but not cheap, and if you have high electricity, the energy to create teh moisture comes from resistance heat, rather than gas heat or heat pump sourced. But they are better if your water rates are high or if you want more precise, more, responsive, more direct humidity control without log fan run times. They also do not consume BTU's for water evaporation, they actually slightly incease net heatoutput when running. The bypass and fan powered consume some BTU's to evaporate the water.

    Flow through (bypass or fan powered) are like carpet bombing with dumb bombs while the True Steam is like a pair of laser guided smart bombs. They both get the job done, by the truesteam is much more precise.

  10. #10
    Join Date
    Dec 2008
    Posts
    90

    Follow up on this one

    Hey, All!

    We just moved into our new (2ksf ranch w/2ksf, currently unfinished basement) house, complete w/3-zone Infinity system (80k BTU 96AFUE, 21SEER a/c) and Honeywell HM509H8908 humidifier ... which has crapped out twice, in one week ("Call Service" indicators, zero output condition).

    When I originally talked with the HVAC guy (I wasn't the builder. I bought a home FROM a builder, and had very little contact w/the HVAC guy, directly), he was telling me about the cool features OF the Carrier setup, including the automatic rollback of humidity, in response to low outside temps, to eliminate condensation.

    But he installed this Honeywell, instead, and -- aside from NOT compensating for that (Northern Colorado = COLD winters!) -- it seems reluctant to ... um ... work.

    I'm thinking about asking him to swap it out for a Carrier humidifier. It seems to me that the fan-powered type is the better option, based on the trade-offs that y'all outlined, above.

    Does anybody have an opinion, one way or the other, about the position I'm taking -- that better control, and automatic reduction in the RH setpoint in response to cold outdoor temps (in other words: full integration with the full Carrier setup) is a better thing than the "precision" and possible efficiency (water in vs. water out) gains of the Honeywell??

    I'd be oh-so-grateful

  11. #11
    Join Date
    Oct 2005
    Location
    MN
    Posts
    133
    I put an Aprilaire 400 on my Ruud Modulating system, and can say its tha cats a#s!

  12. #12
    Join Date
    Dec 2008
    Posts
    90
    Quote Originally Posted by frankt View Post
    I put an Aprilaire 400 on my Ruud Modulating system, and can say its tha cats a#s!
    Does the combination automatically dial back humidity in response to decreasing temperatures??

    I have the feeling that ... in climates like yours and mine ... this can make a pretty big difference.

  13. #13
    Join Date
    Oct 2005
    Location
    MN
    Posts
    133
    Yep, mine does.

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