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  1. #1
    I have a new carrier furnace (model 58MCA120-20) with a carrier flow through humidifier. It has 4 zones and is controlled by a Comfort Zone II display unit. The problem is that the humidifier will run when the furnace is off. I initially thought that it was wired incorrectly but changed my mind when I noticed the display unit indicates that the heat is on even though the furnace (blower, igniter, etc) is off. I believe there is something in the system that is keeping it awake when it should be sleeping. Not only does the display unit indicate the heat is on, but the zone dampers will move at what seems like random times even when the furnace is off for hours.
    I’ve had my HVAC contractor out twice to look at the furnace. He says everything is fine and I don’t care to argue with him because I know nothing about HVAC systems. I was wondering if anybody has seen a situation like this before. Is there something I can ask my HVAC contractor to check? Any help would be greatly appreciated.


  2. #2
    Join Date
    Apr 2003
    Location
    Eugene, Oregon
    Posts
    1,209
    Would that be a 58CMA rather than MCA? Oil fired?
    Proud supporter of Springfield Millers and Oregon Ducks.

  3. #3
    It's a natural gas furnace. Probably a typo when I copied the model number.

  4. #4
    Join Date
    Jul 2004
    Location
    West TN
    Posts
    983
    I left my truck at the office tonight... it has my comfort zone II books in it.

    From off the top of my head...

    The comfort zone II can be set up to just humidify with a call for heat...
    OR
    Be completely independant and keep your humidity at the level your stat is set up for irrigardless of what's being called for.

    There seems to be some custom settings to control it in various ways. Need my book to make sure... but seems to be one setting that even adjusts the humidity your home should have based on outdoor temp. It ramps it up and down to keep it at a level where your windows won't sweat.

    I'm wanting to say that its default setting is to control it when it wants to. Think its called smart demand or some fancy wording.

    The zone system configuration is not something I would want the general homeowner to tinker with... it can cause major major probs if not set up right. For right now... go to your stat and check your humidity level and your humidity setting.

    Have you checked to see what your humidity level is in the house and what it is set for at the thermostat?
    Extend to others the grace that God has given you.

  5. #5
    Thanks, Wormy. I'll play around with the different modes and see if I can find one that works. The humidity level in the house is low. I have to keep the humidistat low to prevent the humidifier from continuously running when the furnace is off.

  6. #6
    Join Date
    Apr 2004
    Posts
    7,680
    It shouldnt run if it's wired to the HUM terminal of the board. That 24v terminal is not energized until after the prepurge period. Then you wouldnt have to worry about the humidfier running when the furnace isnt.

  7. #7
    Join Date
    Jul 2004
    Location
    West TN
    Posts
    983
    OK... I got my truck with me tonight and I've got my
    Comfort Zone II info in my hands...


    First off..
    There are various ways to set up a humidifier with your furnace / system.
    One way is to have it wired to a board in the furnace.
    This allows the furnace to tell the humidifier when to come on (during a call for heat)
    I'm pretty sure thats the way docholiday was mentioning.


    The Comfort Zone II can also be wired to control humidity in the house. From the description of how its reacting, I'd say this is how yours is wired up.

    The fastest way to tell is to check the wiring to the zone system / equipment controller.
    This is a white box about 14" wide and 14" tall thats about 3" thick. It has a door on the left side and a door on the right side. It should have a whole bunch of wires running to it.
    You may or may not have access to this controller.
    IF you can get to it (without getting hurt)
    then open the left door. In the upper left corner, look for a wire connection labeled "HUM HUMIDIFY". If it has a wire to it, then the Comfort Zone II system has control over the humidity. If it does not have a wire to it, then the furnace has control over the humidifier.
    There are alot of ways to connect controls and optional equipment so keep in mind, what I say may not hold true for your system. I would need to see it.

    Now for the Comfort Zone II options...
    Go to your master thermostat (user interface)
    Press SET TIME/TEMP and FAN buttons at the same time to enter humidity mode.
    Either hu (humidify) or de (dehumidify) will appear in the clock display. Use the SET TIME/TEMP button to select hu.
    The actual humidity now appears in the large display, the humidfy set point appears in the heat set point display, and the small triangle icon below the set point is turned on when the humidify output is active. The UP and DOWN buttons now adjust hte humidify set point and the MODE button scrolls through the 5 aavailable humifification modes.

    MODE 1. (Factory Default)
    Normal Humidify Mode. Humidify only when Any Heat is on and Fan are on. (Will provide humidification during call for any call for heat, this includes heat pump mode.)

    MODE 2.
    Fan Humdidify Mode. Blower and Humidifier will run when there is a demand by the stat. Even if there is NO call for heat. the book says this is good for when the furnace is oversized, resulting in short heating cycles. It allows the humidifier to run longer, supplying more humidity to the home. Note that fan hours will increase, using more electricity. Also, the humidifier delevers less moisture to cooler air than it does to heated air.

    MODE 3
    Auto Humidify. Humidify only when Any Heat is on and Fan are on. Humidity level will self adjust according to outdoor temp. The book says..."This feature is designed to eleminate the problem of sweating windows in very cold weather. When selected, the set point is reduced by 1 percent for every drop of 2deg F in outdoor temp between 50degF and 0degF. The set point may be changed at any time. it will conttinue to track outdoor temp from the new set point and the current outdoor temp. Then adjusted set point rantge is still limited beteween 10% and 45% relative humidity. To use thi feature, the outdoor temp sensor MUST be attached. If not, and E3 error message will be displayed."
    (side note.. the outdoor sensor is not REQUIRED on regular heating systems. it is REQUIRED on a Dual Fuel heat pump application. SO the installer may or may not have installed the outdoor sensor. If you can check the outdoor stat at the thermostat, then it is hooked up.
    If it gives you two dashes at the thermostat when you go to check the outdoor temp, then it is not hooked up.)

    MODE 4
    Auto and Fan Humidfy. This is MODE 2 and MODE 3 combined.

    MODE 5. Disable humidification altogether.


    To exit humidifity setup mode, press END. Or dont' touch anything for 3 minutes. all changes are saved automaticly.


    There is a table in my book that shows how you can tell what mode you are in.
    Let me know if you need the table and I'll see if I can post it somehow.


    Long post... I didnt' do a spell check.. so forgive me if I mispelled something hehe
    Extend to others the grace that God has given you.

  8. #8
    Join Date
    Nov 2001
    Location
    east kansas
    Posts
    8,033
    I think all dampers open after a certain amout of time without a call for heat or cool. I think it is 3 hours.

  9. #9
    Wormy,

    Thanks for the reply. I checked the equipment controller and there is a wire hooked up to the HUM terminal. I have the humidifier set up in Mode 1, and based on what you have said and what the set up manual says, I don't think the humidifier should be running when the furnace is not.

    If I hook up the humidifier to the furnace, I'm assuming I will no longer be able to control the humidity level with the Comfort Zone II control unit. I may have to do an add-on control that only turns on the humidifier when the control unit is calling for humidity AND the furnace is on. I can't believe Mode 1 doesn't work this way. Carrier seems to have a little more work to do with this system.

    (I don't have a heat pump system and the equipment controller switches appear to be set correctly)

  10. #10
    I just got to thinking again. The system IS calling for heat based on the Comfort Zone's display which shows a triangle next to the heat indicator. I am really confused now. Why would my system call for heat, based on the signal it sends to the display unit, but the furnace not run? Could it have something to do with the "smart recovery" feature?

  11. #11
    Join Date
    Jul 2004
    Location
    West TN
    Posts
    983
    OK... I dont' have my book handy right now... so I may not answer this correctly.


    Go to the equipment controller again and look at the stat wires again.
    Toward the upper left, maybe a few inches down, you'll see where the control wires connect to the furnace.
    See if there is a wire under W1... the installer might have put it under W2 by mistake. I would NOT move it if I were you, I'd get the contractor to make changes like that. I wouldnt' want you to void your warranty based on something I said.

    Now I may be totally wrong on this next part. I'll try to varify it when I can get my books again.
    When a zone wants the heat to come on, the zone system first checks the temp of the duct. If the temp of the duct is warm enough to heat the zone, it will just turn on the fan and adjust the dampers so that the zone calling for heat can warm up without turning on your heating unit.

    When it is showing that a zone is calling for heat... check the temp for that zone and the temp setting.

    Also, try turning your humidification feature completely off. This way you can widdle down what is bringing the unit on.

    Lemme back up for a moment...
    Are the zones maintaining the correct temperature?
    Is the zone system / humidifier maintaining the desired humidity? (i.e. you have it set on 35% and its keeping the house at 35%)

    If the zones are maintaining the correct temp, and the humidity level is being maintained... then more than likely you don't have a prob.. the system is doing what it needs to do to maintain the setpoints you want. The system will use the best way possible to maintain those setpoints.

    NOW if the system is not maintaining the setpoints.. i.e. you have the humidity set for 35% and its running all the time and ending up at 60%... then you got a prob that needs to be addressed.



    Extend to others the grace that God has given you.

  12. #12
    There is a wire connected to W1, but there is also a jumper wire from W1 to W2.

    Thanks, Wormy. I'll ask my contractor specifically about that connection.

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