Wiring Help - Aprilaire 400

Discussion in 'HVAC Heating & Cooling' started by Michigan Ray, Jan 2, 2014.

  1. Michigan Ray

    Michigan Ray New Member

    Messages:
    17
    Location:
    Michigan
    Hi,
    Newbie here....Wow what a great forum! I have a cabin that I'm currently remodeling. I'm putting in knotty pine ceilings and hardwood flooring. The cabin is a small two story with a total of 1,500 square feet. Current humidity, a terrible 20%. I'm interested in purchasing the Aprilaire 400A with the digital h'stat. Being a drainless humidifier it would work perfect in my situation due to not wasting gallons of water and having a crawl space.
    I have over 30 years of experiance in building, plumbing and residential wiring, but the wiring of a humidifier to a furnace & h'stat is totally new for me. As for installation, the furnace is a downflow design on the main floor with all the main supply/trunk line T'd off in the crawl space. I'm planning on mounting the humidifier right below the furnace (center of the T supply/trunk line). The main return duct is directly over the furnace 14 x 20" x 4' 6" high with the furnace filter laying horizontal right in the middle (2' 3"). I plan on installing the 6" bypass duct in the lower section of the main return. This places the 6" bypass duct between the furnace filter and the furnace. I would rather have the h'stat mounted on a wall, but it appears that it needs to go above the bypass duct by approx. 6". I'd like to add, the furnace is in a seperate 4 x 10' closet shared with a washer & drier. One thing that I will definately install will be a 1/4" shutoff valve instead of a saddle valve.
    Wiring?? I only want the humidifier to run during the heat/fan cycle. My furnace control board (link below) appears to accept what is needed for proper wiring. I'm hoping to find someone that would have a fairly simple diagram and/or explaination in regards to wiring this unit to the furnace, digital control & outdoor temperature sensor. Aprilaire's diagram appears to be a little vague. I want to make sure I'm tying everything in correctly. Also, any of your suggestions would be most appreciated. My furnace is as follows;
    Brand: Bryant downflow
    Model: 373LAV
    Link to wiring specs pages 7-8 (the layout of my furnace is with the supply directly below the furnace "not shown")
    http://www.docs.hvacpartners.com/idc/groups/public/documents/techlit/sp04-62.pdf

    Link for #60 Digital H'stat
    ftp://ftp.aprilaire.com/Fulfillment/Inbox_Lit/60_62_ADHC_install.pdf

    Link to Aprilaire (Right column has an installation manuals for the 400A. Aprilaire 400 Series Humidifier)
    http://www.aprilairehumidifierparts...CI-O7Jy-3bsCFdE-MgodfFYA2Q&CA_6C15C=553764515

    Thanks in advance for taking time in helping me out. Ray
    Last edited: Jan 2, 2014
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,937
    Location:
    New England
    Looks to me like you'd run a pair of wires from the furnace (24vac common and the humidistat terminals) to the indicated terminals on the control unit. The max power draws are close, but within range - double-check but 10VA is less than the 0.5A max your furnace can provide on that path if I remember properly.

    You can check this with a multimeter...if you measure between the 24vac common and the humidistat terminals, there should only be voltage there when the fan is running. Put the black lead on the common and the red lead of the multimeter on the humidistat terminal.
  3. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,135
    Location:
    Maine

    That is exactly correct.
  4. Michigan Ray

    Michigan Ray New Member

    Messages:
    17
    Location:
    Michigan
    Hi,
    Thanks for your help. Below is a picture of my furnace control board and the Aprilaire digital humidistat. I believe the wiring in the diagram is the way to go. I will need at least a solid strand three wire cable. Please correct me if you see that it's not. Thanks again, Ray
    Furnace & Humidistat Pic.jpg
    Last edited: Jan 2, 2014
  5. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,135
    Location:
    Maine
    It is correct. Use standard thermostat wire.
  6. Michigan Ray

    Michigan Ray New Member

    Messages:
    17
    Location:
    Michigan
    :)Awesome!! Two more questions.......Please
    1) Would you tap into the cold or hot water line.
    2) Would you tap directly from well water or into water from a softner? I am putting in a water softner, although my well water is close to being perfect. Just used to softened water.
    Thank you both for all your help, I sincerely appreciate it!! Ray
    Last edited: Jan 2, 2014
  7. Reach4

    Reach4 Active Member

    Messages:
    2,133
    Location:
    IL
    Softened water will make the unit much easier to clean. Definitely softened. Does your unit have an overflow that will continually drain some water? If so, that's good from a keep-clean situatiojn. I think I would go cold pipe in that case, since I would be putting some water down the drain. If not, I think I would go hot, but you will need to clean things out more often than if your unit drains continually.
  8. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,937
    Location:
    New England
    There's various thoughts on hot verses cold to the humidifier. In theory, hot would allow more of it to evaporate but at a cost of 'wasting' hot water. I have mine hooked to the cold water line, and it works fine. The evaporator pads will last MUCH longer if you use softened water if there's any mineral content to the well water. Keep in mind that ALL of the minerals in the water that evaporates will be deposited on the pad. The design of this humidifier will cause it to concentrate some of them in the runoff, but you'll still get a bunch deposited over time.

    FWIW, do NOT use a saddle valve to make the water connection - those are a leak waiting to happen...go to the effort to get a proper valve and tee installed for the supply line to the unit.
  9. SteveW

    SteveW DIY Senior Member

    Messages:
    1,052
    Location:
    Omaha, NE
    Only thing I would add is that if you are running a heat pump, you might want to tap into the hot water line since the air produced by a HP is not as warm as that from a gas-fired furnace, so it is harder to get water to evaporate from the pad.

    I agree with use of softened water -- though you will still get fluffy white deposits on the pad. These deposits seem not to get in the way as much as those from hard water.
  10. Michigan Ray

    Michigan Ray New Member

    Messages:
    17
    Location:
    Michigan
    Hi,
    I couldn't agree with you more on the saddle valves........leak waiting to happen. I have and always will use in line 1/4" shutoffs. As for the Aprilaire 400, it is a drainless humidifer, therefore no water is being poured down the drain. I believe it has an overflow tube just in case there's a problem. It looks like I'll tie into my soft water, just got to decide hot or cold. Thank you for all your input, you folks are great! Ray
    Last edited: Jan 2, 2014
  11. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,937
    Location:
    New England
    In a typical install, all of the water does NOT evaporate as it drains down the pad...a little does go down the drain and this is by design. At least if we're talking the model I think we are. It appears to be a newer version of the one I have (different control, but the rest is the same).
  12. Michigan Ray

    Michigan Ray New Member

    Messages:
    17
    Location:
    Michigan
    Last edited: Jan 2, 2014
  13. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,937
    Location:
    New England
    If you want the humidifier to operate if you run it in fan only mode (assuming it needs to), you'd need those other connections. If you only run the furnace with the fan control in auto, at first glance, you don't need them.
  14. SteveW

    SteveW DIY Senior Member

    Messages:
    1,052
    Location:
    Omaha, NE
    ***************************************************
    QUOTE from Aprilaire website:

    Change your water panel AT LEAST 2 times each humidification season - unlike other humidifiers in the Aprilaire family - the model 400 does not use a rigid aluminum wick. The wick material is more absorbent and has paper-like qualities. Why? Because the water panel on the 400 wicks up moisture from a reservoir as well as being wetted by water dripping from above. Unlike other humidifiers - the model 400 has a water reservoir / float system where they others flush excess water down the drain. The benefit to using the 400 is decreased water usage. With this benefit comes additional maintenance. The most important maintenance item is more frequently changing of the water panel, which is part # 45.

    *********************************************

    The 400 series is unique in that it doesn't have the flow-through system the others do. It lets some water, that in other humidifiers would drain off, sit in a reservoir at the bottom of the unit and then get wicked up onto the pad.
  15. Michigan Ray

    Michigan Ray New Member

    Messages:
    17
    Location:
    Michigan
    Awesome...... I'll skip using the G and Gf terminals. As I stated earlier on, I only want the humidifier to run during the heat/fan cycle only. I assume that the W to W wiring is also not needed.
    Maintenance wise, yes I totally agree that it is important to keep on top of cleaning and changing out filters. After all the research that I have done, I believe that the Aprilaire 400 requires a little more maintenance. With that being said, I truly believe it's a great trade off compared to wasting gallons water daily with a flow through and higher electric bills with the steam type.
    I will follow up through this post to let everyone know how it went with the install. It may be a few weeks due to ordering and getting to the installation. I can't thank you enough for your time in helping me out with this project. I sincerely appreciate everything, Ray
    Last edited: Jan 3, 2014
  16. DonL

    DonL Banned

    Messages:
    3,982
    Location:
    Houston, TX
    Humid air can be a health hazard, and May not even be needed.

    If you do not get nose bleeds, Then the Humidity is fine.

    Needing a Humidifier in Michigan kind of makes me wonder.

    Set a pan of water on a hot register and be done with it.


    Have Fun.
  17. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,937
    Location:
    New England
    My guess is that some prudent air leak sealing would help a lot, but may not be that easy to perform. The ducts may not be well balanced, which makes things worse, drawing in outside air. But, that unit comes with an outdoor sensor, and adjusts the indoor humidity to help (not prevent if you set it too high) keep the indoor air at a point where you should not get condensation.

    From personal experience, I find anything less than 20% annoying, and that's easy to get in an older, leaky house with forced air heating. Sealing it up will save not only energy, but make it more comfortable in the process.
  18. Michigan Ray

    Michigan Ray New Member

    Messages:
    17
    Location:
    Michigan
    Couldn't agree with you more.... Thanks, Ray
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