Page 1 of 2 12 LastLast
Results 1 to 13 of 16
  1. #1
    Join Date
    Jul 2007
    Location
    Madison, WI
    Posts
    12

    Honeywell IAQ & Aprilaire 600

    Hi - I've got a Honeywell IAQ thermostat, AMV9 furnace, ASX14 AC & Aprilaire 600 humidifier. Basically, I want the house to be humidified to the percent I have set on the thermostat unless I've lowered the "frost protection" setting below 10. My install company says I can't do this with the IAQ and if I want my house at a set humidity percent all the time, they would need to remove the Aprilaire from the IAQ and I would have to use a manual dial in the basement.

    They've also told me the Aprilaire only runs when the furnace is on a heat cycle, and it won't run when just the fan is on.

    Is this info accurate?

    thanks.

  2. #2
    Join Date
    Mar 2005
    Location
    burlington county n.j.
    Posts
    9,763
    iaq can force fan to run when humidity is called for. its all in the setup.

  3. #3
    Join Date
    Dec 2006
    Location
    Northern VA
    Posts
    389
    It's all in the setting by the installer. Works fine in my house.

  4. #4
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,758
    The IAQ can run the humidifier even if its not calling for the furnace to heat the house.
    You may want the humidifier piped off of the hot water pipe if you want to add moisture when the furnace is not runnning for heat.

    Sounds like your contractor doesn't know anything about the IAQ stat.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  5. #5
    Join Date
    Jul 2007
    Location
    Madison, WI
    Posts
    12
    The IAQ is set to "Humidify forces fan on", but when the installer was here, he checked something in the basement and said it was only humidifying on heat cycles. I think he said that if I wanted it to also humidify when just the fan was on, he'd have to disconnect the outside thermostat, which would remove the frost protection feature. Then he said if I wanted my house to stay at a set humidity percent all the time, he'd have to hook the manual dial up in the basement with some kind of jumper modification. I asked him if he could just hook things up so that when frost protection is set to 10, my house will always be humidified to the percent I have set. I couldn't get a straight answer out of him. He also kept talking about how I don't want moisture running down my walls because then I'd have mold. I agree I don't want that, but I don't think that will be an issue unless I have humidity set near 100% and there's some serious condensation going on with my external walls. He disagreed, telling me 30-35% humidity is the sweet spot for winter. That's a little too dry for me.

    This install company has at least 1 guy who knows this thermostat well & installed one at his own house. I'll call back and specifically request that guy. But before I do, I just want to make sure I have reasonable expectations of my HVAC equipment -- if it's, for instance, 20 below zero & 0% humidity outside, I have the thermostat set to 68, frost protection set to 10 and humidity level set to 50%, can I expect my house to actually get to 50% and stay there? If I start getting frost on my windows, I'll lower the frost protection setting and expect my indoor humidity percent to drop as needed. My house is about 2300 square feet and my HVAC equipment is listed in my first post above.

    thanks.

  6. #6
    Join Date
    Jun 2007
    Location
    Metro St. Louis
    Posts
    181
    Condensation occurs on the outside walls and the windows because they are colder than the indoor air.

    The real problem occurs inside the walls. Your house breathes. Air exits, and air enters thru all of the little holes and seams. The moisture also can get into the wall cavities and condense on the outside wall's sheathing. And then the mold grows.

    To avoid this problem, the target RH% should reflect the outdoor temperature. According to your Aprilaire Owners Manual, at 40* outside, the ideal is 45%RH. Every 10 degrees cooler lowers the %RH by 5%. At 0*, target is 25%.

    I understand the desire to have some humidity to control static and cracked skin, etc. But you don't want to have to have your house condemmed due to mold as a result.

  7. #7
    Join Date
    Sep 2007
    Location
    South
    Posts
    89
    Quote Originally Posted by Waterloo View Post
    Condensation occurs on the outside walls and the windows because they are colder than the indoor air.

    The real problem occurs inside the walls. Your house breathes. Air exits, and air enters thru all of the little holes and seams. The moisture also can get into the wall cavities and condense on the outside wall's sheathing. And then the mold grows.

    To avoid this problem, the target RH% should reflect the outdoor temperature. According to your Aprilaire Owners Manual, at 40* outside, the ideal is 45%RH. Every 10 degrees cooler lowers the %RH by 5%. At 0*, target is 25%.

    I understand the desire to have some humidity to control static and cracked skin, etc. But you don't want to have to have your house condemmed due to mold as a result.

    Great explanation!! I was about to buy a manual control humidustat as I couldn't see much the point of using an automatic but where I live outside temp. changes drastically from day to night (20 to 30F) in the winter and I wouldn't be able to keep up with the dial.
    What's another word for Thesaurus?
    - Steven Wright

  8. #8
    Join Date
    Dec 2002
    Location
    Rochester, MN
    Posts
    5,305
    On that t-stat you can set it up with "frost guard on" with outdoor sensor, or turn it off.

    You want the stat to adj the humidity when it get cold out.. I have mine set to goal of 45%, Frost guard at 5, and use outdoor sensor,, it works very well.

    Sounds like the dealer don't know the t-stat very well...

  9. #9
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,758
    50% RH when its 15* outside is asking for trouble.
    And unless you have that Aprilaire hooked to the hot water pipe it won't do it on the average house.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  10. #10
    Join Date
    Dec 2002
    Location
    Rochester, MN
    Posts
    5,305
    Quote Originally Posted by beenthere View Post
    50% RH when its 15* outside is asking for trouble.
    And unless you have that Aprilaire hooked to the hot water pipe it won't do it on the average house.
    What do you mean by that??

  11. #11
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,758
    50% RH at the stat on an inside wall when its 15 outside can cause some areas around the windows or receps on the outside walls to be at 70% or higher, possible mold problems.

    Aprilaire 600 doesn't put a lot of moisture into 70* air, so connecting to hot water pipe at the WH helps.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  12. #12
    Join Date
    Jul 2007
    Location
    Madison, WI
    Posts
    12
    thanks for all of the excellent info here! with the frost protection enabled, is there a setting between 1-10 that will ensure no moisture buildup inside the walls? or at least come pretty close? ideally, i'd like somewhere around 45% humidity in the winter, unless the frost protection has lowered the humidity to prevent frost/moisture buildup. also, the aprilaire is hooked into the hot water line, so i think i'm set there.

  13. #13
    Join Date
    Dec 2002
    Location
    Rochester, MN
    Posts
    5,305
    Just set it at 45%, and Frost guard at 5.

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event