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  1. #1

    Confused Whole house humidifier options

    Hi

    I would like some advice on humidifier options for a new house I'm building in Manhattan Beach California.

    I know humidifiers are not really required where we live, but we do run portable cool mist ultrasonic humidifiers in our bedrooms at night during the winter, so I may just as well install a whole house humidifier instead or in addition.

    New construction, 3800sqft house, 10ft ceilings, two story, dual HVAC systems, dual Nest controllers, one system for upstairs and one for downstairs.
    Downstairs FAU mounted horizontally in garage, upstairs FAU mounted vertically in closet (no space in ceiling due to low pitch of roof and build height restrictions).
    Equipment is Goodman high efficiency (95% downstairs and 96% upstairs) natural gas heaters, I don't know the exact model numbers.
    75cfm 24/7 whole house extractor fan per local building codes.

    From my own research I was planning on using AprilAire 700 or Honeywell TrueEase HE300 fan powered evaporative pad humidifiers.
    They seem to be a reasonably energy efficient (compared to steams hig electrical cost) and hygienic (compared to drum humidifers where water stand) option.

    This morning my HVAC contractor, who admits to having limited humidifier installation experience due to the local climate, brought me a Skuttle 592-22 Spray Humidifier.
    He says the supply house "old timers" say this is the way to go as they have very few returns on this unit.

    So I really have the following questions:
    1. Should I even consider a spray humidifier, I thought they are no longer used?
    2. Between AprilAire 700 and Honeywell HE300, which one?
    3. Space in upstairs FAU closet is limited, contractor suggest to install humidifier on A-coil unit instead of reworking ductwork to make plenum large enough for install. Is installing the humidifer on the a-coil unit acceptable?

    Thank you
    Pieter

  2. #2
    Join Date
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    I've got a bypass style AprilAire on my own home in SoCal and think it works fine. It's probably better than the steam or spray types, especially with the hard water I have at my house, as I just change out the pad at the beginning of each winter. It's simple, and easy to maintain.

  3. #3
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    Not a fan of spray/atomizing humidifiers.

    Aprilaire 600 or 700 or Honeywell HE300.

    Of course, running the exhaust fan 24/7 is probably causing a lot of your low humidity.
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  4. #4
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    If you build a tight house, you won't need to add humidity. You may need to remove it or use a ventilator! And save on utility bills.

  5. #5
    Thanks for replies.

    This is a brand new construction, so should be pretty tight, but with our moderate climate, there isn't too much inspection of insulation or sealing.
    The 24/7 ventilation fan is an energy efficiency building code, I'm not allowed to have a switch in the line, must be directly switched from distribution panel.

    I did consider the Aprilaire 600 fanless bypass unit, but there is not enough space for the bypass plumbing upstairs, so a fan unit is more practical given the tight space.


    What about the suggestion to install the humidifier directly on the A-coil unit, any issues?

    P.

  6. #6
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    I have my bypass unit installed on my A-Coil, with the bypass line then ducted back to the suction side of the blower on the furnace. I see nothing wrong with it, as long as whoever is doing the work knows where to cut and where not to cut. What you don't want is to be bypassing the coil with the cut, or worse, sawing a cut in the coil. The A-coil box itself, is just that, an air box, no reason it can't be used as such.

    I'm pretty sure the installation instructions for the Aprilaire models even show the proper way to mount it to the A-Coil.

  7. #7
    Ah, you're right, the diagram does show it mounted on A-coil.
    Ok, thank you.

  8. #8
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    On a basement upflow installation, install the hum on the return drop so when it leaks, it doesn't leak on the furnace.

  9. #9
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    Quote Originally Posted by BaldLoonie View Post
    On a basement upflow installation, install the hum on the return drop so when it leaks, it doesn't leak on the furnace.
    I think that is one of the primary reasons to mount it TO the A-coil, a problem that results in a leak (plugged drain line, for instance) will simply overflow into the A-coil, and be collected/handled by the condensate drain pan.

  10. #10
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    A home on the coast in a mild climate like California I wouldn't think if built to even reasonable tight or just well constructed to code, would need a humidifier. I would actually want fresh air ventilation, and wouldn't even bother with a ERV or HRV (too few HDD and CDD). I suppose when temps drop in to the 30's for a few weeks it's nice to add a little humidity if needed. A fan powered, non bypass type might be best.

    The best solution is to just construct the home properly so you don't need one.

  11. #11
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    The coast isn't always humid in cali. in fact, a lot of the fall-winter months, when there is a strong off-shore flow, the dew point runs in the 20s or below. Outside ventilation can very rapidly dry out any moisture collected in a home (a 20°dF OSA results in a 14%RH@72°F). Certainly dry enough to give respiratory issues to sensitive folks. This is also at times where there isn't really a heating demand either. It's usually only for days at a time, but it is enough to where a humidifier can make for a nice added comfort.

  12. #12
    Join Date
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    Quote Originally Posted by CraziFuzzy View Post
    I think that is one of the primary reasons to mount it TO the A-coil, a problem that results in a leak (plugged drain line, for instance) will simply overflow into the A-coil, and be collected/handled by the condensate drain pan.
    It doesn't all flow into the drain pan. A good amount can run down the outside of the plenum. Unless your caulking the bottom of the housing to the plenum.
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