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  1. #1
    Join Date
    Sep 2007
    Location
    Chicago, far-western suburb
    Posts
    33

    Humidifier - Power Source and Water Quality

    I had a replacement HVAC system installed in June of last year.

    I won't go into the details of how disappointed I was in the installation after doing my darndest to be a knowledgeable customer by reading this forum and asking questions (thanks again to all the forum members that helped me).

    Anyway, the system included an A/S HUMD200 bypass humidifier (I think it is the same as an Aprilaire 500M). As it never worked, I took a look and it was not wired correctly to the Honeywell - Equipment Interface Module (I am an Electrical Engineer - boo, hiss!). It was wired as a "powered type" device (i.e. the EIM only provides a contact closure), it should have been wired as an "un-powered type" where the contact closure actual routes the "juice" from an external power source to the water valve. I told the installing HVAC company about this and they explained that they would only have to do a minor rewiring at the EIM.

    My question to them was if the 24VAC that was coming from the furnace (to run the thermostat) had sufficient capability to power the 24VAC@0.5A (12 Watt) valve solenoid. Their answer was that "they always did it that way with no problems".

    As the humidifier did come with a transformer (which was not used), and the install manual for the furnace does not mention anything about 24VAC power sourcing for add-ons, is it correct to power this humidifier from the furnace?

    Also, does anyone ever add an in-line water filter (such as used for refrigerators) to the humidifier water supply input in order to try and minimize "crud" build up inside the unit? I know that filters need to be changed regularly, but was wondering if adding a filter would increase the life of the water valve and keep the insides cleaner. I have iron well water and unfortunately I did not catch that they "saddle valved" to the wrong side of my softener - this has to be corrected anyway but could adding an in-line water filter help (as long as they are going to re-pipe the thing)?

    Thanks

  2. #2
    Join Date
    Sep 2009
    Location
    Arnold mo
    Posts
    3,966
    Your new furnace will have a 24v terminal on its circuit board for Hum and I believe most of them will handle 1 amp., so a solenoid valve rated at .5 should be find. They may have bypassed your water softener on purpose. Check your literature on that. I know there is a thread somewhere around here that goes into it in detail. I can't remember. Do not put another saddle valve in. Use a ball valve.

  3. #3
    Join Date
    Sep 2007
    Location
    Chicago, far-western suburb
    Posts
    33
    I have an American Standard AUH2B060A9V3VAA, 60K, 95%, furnace.

    As far as I can tell from the install manual, there is only an option to route 120VAC @ 1A for a humidifier. There is no mention of powering the humidifier with 24VAC. Also I took a look, and the 24VAC transformer in the furnace is rated at 35VA (~1.46A).

    Would Trane / AS purposely oversize their power transformer by 50% in order to run an add-on and not mention it?

    This is the kind of stuff that I have been running into with my new installation from an A/S - "Customer Care" contractor.

  4. #4
    Join Date
    Sep 2009
    Location
    Arnold mo
    Posts
    3,966
    Quote Originally Posted by Everlast View Post
    I have an American Standard AUH2B060A9V3VAA, 60K, 95%, furnace.

    As far as I can tell from the install manual, there is only an option to route 120VAC @ 1A for a humidifier. There is no mention of powering the humidifier with 24VAC. Also I took a look, and the 24VAC transformer in the furnace is rated at 35VA (~1.46A).

    Would Trane / AS purposely oversize their power transformer by 50% in order to run an add-on and not mention it?

    This is the kind of stuff that I have been running into with my new installation from an A/S - "Customer Care" contractor.
    My mistake about the 24 volt terminal. You are correct in that it is 120v. I've always used the transformer that comes with the humidifier and tap into the 120v on the line from the service switch. So it's just memory that tells me it's ok to get this hum transformers power from that board, but I've seen em tapped into the furnaces transformer 24v line with no ill effect.

  5. #5
    Join Date
    Dec 2007
    Posts
    4,702
    most, if not all, humidifier install instruction specifically state to NOT use softened water!!
    so an inline filter on the water line would be a good thing. also, as stated use a ball valve instead of the saddle valve.

    as for the wiring I would follow the manufacturers wiring schematic(s). can't go too far into detail, forum rules, but the use of a dedicated transformer and isolation relay is required by 2 or 3 mfr that I know of.

  6. #6
    Join Date
    Sep 2007
    Location
    Chicago, far-western suburb
    Posts
    33
    Note that I have no intention of performing this work. I just want to keep the installers from burning the house down!

    Sorry, a little background info -
    I picked my contractor because he was a new owner of an established HVAC company (figured a new owner wanted to get as many satisfied new customers as possible), was knowledgeable and appeared to think "quality". Unfortunately, he got Abbot and Costello as his installers along with the business. He has fixed every fixable problem that I found so far (can't do much about the brazing without nitrogen, or the sawzall hole in my siding for the vent pipe).

    Pacnw comments made me realize that I am guilty of the same thing that my installers were - NOT READING THE INSTRUCTIONS!

    The manual for the humidifier states that the humidifier will "...operate effectively using either hot, cold, hard or mechanically softened water." and went into the pro's and con's of these water characteristics. At this point I will use cold water (for convenience sake but will move to hot water "for increasing capacity" as the manual states, when I get my new hot water heater) and softened water (I do have a great deal of iron in my un-treated water) along with an in-line refrigerator water filter (which I will change every year as they are only good for about 2000 gallons).


    The powering and on/off operation of the humidifier, is still not clear to me.
    The Honeywell IAQ Installation guide shows the humidifier 24VAC power being tapped off from the feed from the furnace. The humidifier install guide states "Important - use the 120 VAC power source on the integrated furnace control humidifier accessory terminals marked HUM-H, HUM-N to power the humidifier control transformer". The furnace install guide states "These leads provide 115V power for connection of electronic air cleaner and humidifier. Max load 1.0 Amps each". My interpretation of all this information is that if you do have an IAQ system (that controls humidity and knows when the furnace is running) you should just let the IAQ do all the "figuring" and wire the transformer primary, permanently to 120VAC and run the secondary 24VAC power through the IAQ humidifier contacts and if you don't have an IAQ, but do have either an external humidistat or optional furnace humidistat, that you let the furnace power the humidifier transformer (because it knows when the furnace is running). I guess a third option would be to power the humidifier transformer through the contact on the furnace (so that the transformer is not powered all the time) and still let the IAQ determine when to supply the transformers 24VAC to the humidifiers water valve.

    Again, I will not be doing the work, but I would like to know the "proper" way to do this when my contractor comes by next week. Thank you

  7. #7
    Join Date
    Sep 2007
    Location
    Chicago, far-western suburb
    Posts
    33
    Well I got the filter from Menards (DuPont WF-IR100). Good thing I read the specs though as this filter is only rated for use up to 100F. Can anyone recommend an inline filter that is rated for hot water (and is not really expensive)?

    Still hoping someone will comment on the "proper" way to wire the power to this humidifier given the 3 different manufacturer's instructions. Thanks

  8. #8
    Join Date
    Apr 2009
    Posts
    523
    Think you are making this too complicated. The 40va transformer will be fine to power the humidifier and IAQ stat plus the relays and controls of its own control board/gas valve. That shouldnt be an issue.

    The H terminal on the IAQ module is a dry set of NO contacts. So you just need power on one side and the other H connected too the solenoid then back to common.

    Then humidity can be control via the thermostat and all is well. Since the thermostat will know when its powering the furnace it will know when to close the humidifier contacts (if the thermostat is set up properly).

    And you could always isolate the voltage with another transformer through the IAQ H terminal if it will give you the peace of mind of being done "as spec'd".

    I personally would not worry too much about the a water filter (personally) because the water panel needs to be changed every 6-12 months anyway. And with it goes any "crud". Sediment CAN/COULD clog the orifice of the humidifier (which I rarely find) but if thats the case you should be investing in a whole house sediment filter. Humidifiers that include a filter are usually steam humidifiers that have a filter to reduce minerals and chemicals that cause scaling.

    The humidifier works off evaporation. So hot water will work better. But a gas furnace makes a good amount of heat, and sometimes cold water with gas/oil is good enough plus its less expensive. So if it were mine I would try cold water for a while and check humidity levels and if not satisfied then goto hot water. I ran an AA500 for years with cold water and it did "good enough" and since I dont pay for water (homeowners assoc. does) I figured the price was right too..

    I laughed out loud about "Abbot and Costello"....haha

  9. #9
    Join Date
    Aug 2009
    Location
    Beatrice, NE
    Posts
    2,070
    The furnace transformer may or may not be big enough, it depends on what other loads are on the control system. If you are running a hybrid system, furnace/heat pump, no way. if it is a furnace/Ac, it should have capacity to spare. The wiring then comes down to the system type and any added controls. As far as the differant wire diagrams from differant manufactures, they are all doing the same thing just in differant ways, the tech needs to figure out the best way for your system.

    Good luck.

  10. #10
    Join Date
    Apr 2009
    Posts
    523
    Quote Originally Posted by kls-ccc View Post
    The furnace transformer may or may not be big enough, it depends on what other loads are on the control system. If you are running a hybrid system, furnace/heat pump, no way. if it is a furnace/Ac, it should have capacity to spare. The wiring then comes down to the system type and any added controls. As far as the differant wire diagrams from differant manufactures, they are all doing the same thing just in differant ways, the tech needs to figure out the best way for your system.

    Good luck.
    I think the power usage on the low voltage side is debatable. Only reason is because I've done it at my house. Dual fuel + IAQ + bypass humidifier (now steam).

    From what I've seen in the field I had no problem doing this and not surprised it worked. I've seen Dual Fuel + bypass humidifer + 3 thermostats (no batteries) + 4 24v zone dampers + zoning controller work. All powered from the furnaces transformer. And yes I was surprised, but it worked just fine.

  11. #11
    Join Date
    Sep 2007
    Location
    Chicago, far-western suburb
    Posts
    33
    Just an update -

    The humidifier is working just fine.

    I had the humidifier wired so that the 24VAC humidifier transformer is powered through the furnace HUM relay (120VAC@1A max) and then the 24VAC is routed through, and under the control of, the IAQ HUM relay.

    I really think that this is the correct way to do this especially after emailing American Standard support about this. Their response was that the furnace transformer is not "oversized" in order to handle external loads and that the furnace HUM relay should be used for this purpose.

    Also, I am glad that I added an in-line water filter to reduce the buildup of iron scale on the humidifier parts. The humidifier has only been running (a lot) for a couple of weeks now and I can see quite a difference in the filter's IN versus OUT tubing color (hope you can see the difference in the picture). Thanks again
    Attached Images Attached Images  

  12. #12
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,930
    Fortunately. You can hold that filter lower and away from the EIM when you change it.

    The EIM is not rated to have water splashed or dripped on it.
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    How-to-apply-for-Professional

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

  13. #13
    Join Date
    Sep 2007
    Location
    Chicago, far-western suburb
    Posts
    33
    I was a bit worried about the EIM being mounted to the furnace but you are right because as we all know - "It's not the heat, it's the humidity!"

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