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  1. #1

    Honeywell IAQ with Carrier Infinity Furnace

    I have a Honeywell IAQ thermostat controlling a Carrier Infinity furnace and A/C Condenser. I cannot get the IAQ thermostat to lower the fan speed via the furnaces DHUM terminal. I have the thermostat set as follows:

    0379 Dehumidification Control *1* (Dehumidify with air conditioner)
    0383 Over-cooling limit *3* (3 deg. F)
    0390 Dehumidification away mode *0* (no)

    I realize that there are more settings, but with the 0379 set to *1*, the others are blocked out.

    If I change the setting to a whole-house dehumidifier (0379 set to *3*) (which mine is not) the relay on the EIM closes, so I know that works. I turned it back to the "use air conditioner" setting. It allows the temperature to be as low as 3 deg below setpoint, but it will not close the DEHUM contact on the EIM.

    I understand that the infinity furnace uses reverse logic on the DEHUM terminal, that is, it lowers the fan speed when there is NOT a signal on DEHUM. I may have to install a relay to make that "forward logic" but I will cross that bridge when I get there

    Does anyone have any thoughts on what is happening here?

    Just a side note, I have read on other forums as well as in the owner's manual that I shouldn't see the Auto/Off option on the screen when dehumidifying with the A/C. I DO have that option, however. I am guessing that is a typo in the owner's manual??

  2. #2
    Join Date
    Mar 2007
    Location
    Myrtle Beach, SC
    Posts
    2,919
    Not having the Infinity controller running your system is a mistake. Infinity is a SYSTEM. Now you have rigged it by using someone else's controller. Get the Infinity controller and all will be well. You have lost a lot of the functionally with your current setup.
    Remember, Air Conditioning begins with AIR.

  3. #3
    Join Date
    Jul 2004
    Location
    Massachusetts
    Posts
    6,837
    So who do you think knows the Carrier furnace better, Honeywell or Carrier? The Infinity control was purpose designed for the Carrier Infinity line of products. Getting an after market t-stat IMO was a waste of money and a silly decision. If you already had the IAQ, then bite the bullet and anti-up for the User Interface and you'll get all the bells and whitsles from just ABDC wiring. It's not just a thermostat, it's a communications center.
    If YOU want change, YOU have to first change.

    If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

  4. #4
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,344
    Tell it to dehumidify with whole house dehumidifier. That's what I have to do with my Tappan. It does things backwards too.

  5. #5
    Join Date
    Dec 2006
    Location
    Middle Tennessee
    Posts
    11,347

    *

    for once i agree with Kevin O



    .

  6. #6
    Join Date
    Feb 2010
    Location
    butler pa
    Posts
    1,073
    thats almost as bad as using a heat/cool t-87 on that furnace...

    get the infinity control and enjoy the benefits of the SYSTEM....

  7. #7
    Join Date
    May 2010
    Location
    SF Bay Area, CA
    Posts
    390
    Quote Originally Posted by BaldLoonie View Post
    Tell it to dehumidify with whole house dehumidifier. That's what I have to do with my Tappan. It does things backwards too.
    with that setup it would slow the fan, but wouldn't overcool to dehumidify though?

  8. #8
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,344
    Not sure on the overcooling. I so seldom use the DOD feature can't say. My house tends to stay in the lower 50s %wise so I don't slow the blower much.

  9. #9
    I battled between the infinity controller and the iaq thermostat. I chose the iaq because it is touch screen and has no buttons. I felt that the iaq thermostat was just a little easier to use and if it did the dehumidify like I thought it was supposed to do, it would operate perfectly. Does anyone know if that terminal is supposed to close upon dehumidifying if using an A/C? If a person didn't have a variable-speed furnace, then I would think they just wouldn't use that terminal and would only use the 3-degree setback feature. I guess I just don't understand why this relay isn't closing.

    You guys seem pretty sold on the infinity. My HVAC contractor suggested it, but he just didn't sell me on it. Here's your chance What does it do that my IAQ won't? You'll have to convince me to go back to buttons...I don't know why Carrier hasn't went touch screen.

    Thanks!!

  10. #10
    Join Date
    Feb 2010
    Location
    butler pa
    Posts
    1,073
    well...
    infinity has built in diagnostics for your furnace and ability to set dehum,humidify,customize blower settings ( overrides dip switches on board )
    can stage 2speed ac,stage furnace,does static pressure check,
    all w only 4 wires...

    and a very user friendly control ( i have one in my house )

  11. #11
    Join Date
    May 2010
    Location
    New Jersey
    Posts
    1,309
    To the installers: the homeowner doesn't know the advantages or disadvantages. This is a consultative selling or customer support period, not an attack and criticize one.

    As everyone here was saying, the Carrier ICS is a communicating thermostat. Mimicking commercial direct digital controls, the Carrier system and to a lessor extent systems from Trane, Goodman, Lennox, Nordyne, and shortly York, combine knowledge of indoor temp and humidity, outdoor temp, and system status to operate the system to provide the best comfort and efficiency levels. They also can provide additional functionality: http://hvac-talk.com/vbb/showthread.php?t=610222

    The ICS furnace is three stage...the Honeywell IAQ doesn't have a way to take advantage of that directly.

    That said, I don't think the Carrier ICS knows how to drive an external dehumidifier. If its greater system knowledge (does it have a LAT and/or EAT?) it is able to bit compressor level and blower speeds to provide better dehumidification than just the dehumid fan speed can.

    Does your dehumidifier use the same return and supply ducts as the the furnace? Dehumidifiers can be setup either using their own ducts, using their own return and sending their supply into either the furnaces supply or return, using the furnace's return and sending their supply either into the furnace's return or supply. When configured to let their supply flow into the furnance's return, they have to be configured to either turn on the furnace or only run when the air conditioning is on.

    Does someone know how a Carrier ICS works when an external dehumidifier is installed?

  12. #12
    Join Date
    Mar 2007
    Location
    Myrtle Beach, SC
    Posts
    2,919
    Quote Originally Posted by Airmechanical View Post
    for once i agree with Kevin O



    .
    I am going to write that one on my calender!
    Remember, Air Conditioning begins with AIR.

  13. #13
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,368
    Quote Originally Posted by Kevin O'Neill View Post
    I am going to write that one on my calender!

    Should we make that post a sticky. LOL
    Contractor locator map

    How-to-apply-for-Professional

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

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