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  1. #1
    Join Date
    Mar 2019
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    Question Aprilaire 800 in Denver area 2 story house - will it work


    Had a HVAC contractor (national name that's been in business decades) come to clean our ducts and while here suggested that this unit would solve our extremely dry interior climate that's causing dry skin, too much dust etc.
    Here in the Denver/Boulder CO area it's very dry in winter, especially with forced air heating throughout the entire home.

    We have a 5000sq ft home, basement, main living level (ground floor) and upstairs bedrooms.
    Home entrance area on main level is very open, with vaulted ceiling all the way up the stairs to the upper hallway that leads to all the bedrooms - I'd estimate the ceiling is probably close to 20ft high.

    Main Furnace in basement utility room for basement and main living area.
    Secondary furnace in attic for upper floor (4 bedrooms) only - ducting is very different from main furnace, in that it's all these insulated flexible hoses coming from a central plenum that are suspended throughout the attic, to the vents in the ceiling of each bedroom upstairs.
    In addition to these flexible supply hoses, there's 3 much larger diameter flex hoses that connect to large/square ceiling returns grilles - we change the filters in these so I know these are the returns.

    HVAC company suggested we install the Aprilaire 800 in the basement furnace, running it at it's maximum 240v output, upto 34 gallons of water turned into steam per day.

    Was about to pull the trigger on the install, but thought I would call Aprilaire directly to get their opinion.
    They said we would most likely be disappointed with the results, and the upstairs bedroom floor would likely not improve much at all.
    The tech explained that where there are vaulted ceilings, it's very hard to get the moisture up to the upper floors.
    They said that they would strongly suggest a second unit in the attic furnace, but there is no water supply to the attic furnace, so we would have to tear out walls to tap into bathroom water supply, and then also drain.
    The drainage may not be a big issue since there are several 2" black plumbing pipes venting up through the attic and out through the roof of the house - I'm guessing the humidifier could connect to one of these vents, since these will be connected to drains in bedroom bathrooms, and the humidifier is only going to be dripping water, so would not impede vents. Right?
    What about the type of ducting in the attic furnace? I'm concerned there may be the potential for mould in these flexible duct hoses?

    Aprilaire also suggested a different kind of unit (the 350/360 models) which are essentially 'plug in' units that mount in the ceiling joists in the attic and push humidity from the upper floor ceilings>
    The issue is that this house is 15 years old and the attic is not 'conditioned' so gets extremely hot in summer and stays pretty hot in winter - this would likely negate such a humidifier? Right?

    Aprilaire also suggested that if it was possible to run a line from the 800 in the basement to the attic furnace, then this could work, but that seems like a big job, since the only way to feasibly do that is to follow the main exhaust from the hot water heater next to the furnace as that vents up through the middle of the house into the attic and finally venting through the roof to the outdoors. Not sure if this would be to code to have a humidifier line running next to this vent?
    This could also be a good way to run water supply (1/4" copper) to a humidifier unit in the attic, but again I am not sure what code has to say about this?

    I called the HVAC company with this info and they said Aprilaire is wrong and the single 800 series at 240V would provide humidity to the entire home and we would be very happy.

    Sadly, I'm inclined to believe Aprilaire since they don't have a vested interest as I would not be buying the unit from them directly, whereas the HVAC company would be making several thousand dollars to install a unit that costs a fraction of the total cost.

    Appreciate advice, it would be a shame if the HVAC guys were BS'ing me just to make a buck - surely they know just how dry the climate is here and whether the unit would work or not?
    It would be several thousand to install, so I don't want to get screwed over to find that we are still suffering from dry conditions upstairs.


  2. #2
    Join Date
    Mar 2019
    Sussex County, Delaware
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    I would tend to disagree with Aprilaire in regards to which model would work best for you. Not knowing the details on your water supply makes things a little difficult for me. Steam humidifiers are the most efficient option available. When i say efficiency i mean water usage. If you are paying for a municipal water supply, the cost of water is not cheap. Therefore you will want a unit that does not waste a lot of energy down the drain. If you install (2) model 800 units, you could save on the cost of install and operate them on 120v by using the furnace electrical supply (assuming the circuit/wire can handle the added load). It's very uncommon for a home to need two model 800 humidifiers running on 240v cranking out 60 plus gallons of water a day. I would ask your contractor their opinion on installing two separate model 800 units connected to 120v circuits that are existing in place from you furnaces.

  3. #3
    Join Date
    Mar 2019
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    Thread Starter
    I was reading some more about the power consumption at 240v.
    If this thing runs for an hour it will b 4.5KW/h, which is about 52 cents where I live.

    Assuming the 800 model is going to be pushing hard to humidify my home, I'm wondering just how many hours a day this will run to achieve 40% humidity?
    If it's running close to 24 hours a day (I would have running with blower fan always set to on so it can humidify regardless of heat cycle), then this would present a massive jump in monthly electricity bills somewhere in the $350-400 per month increase!

    This would not be sustainable

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