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  1. #11
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    Jul 2009
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    Default Re: heat system cycling on and off

    The Heat strips should not be coming on while the stat is in the vent or on position. As I said the vent or on pos. is for air circulation. It very well could be going off on high limit, but any Tech that looks at this system and sees that the Heat Strip is coming on when that stat is at the on or vent pos. will have to fix this first. IMHO it's not High Limit. Please don't take this as an argument I'm just going by what the OP posted.

    Then again all I know is duct sealing, according to some.
    Last edited by Sten; 03-06-2010 at 11:33 AM.

  2. #12
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    Fayette County, Ohio
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    Default Re: heat system cycling on and off

    Sten,
    Unless these systems work differently than other systems, you can have the blower on continuously and the heat heat strips are still controlled by by the thermostat being in the heat position and calling for heat, you can also run the blower on continuous mode and have the cooling turning on and off as the thermostat calls for cooling. The thermostat fan auto/on control and it's heating/ cooling control are separate.
    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  3. #13
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    Jul 2009
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    Northeast
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    661

    Default Re: heat system cycling on and off

    So your saying the blower is on 24/7 with both heat and A/C, OK

  4. #14
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    Jun 2007
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    Default Re: heat system cycling on and off

    No, I'm saying that the fan can be turned to the on position, the blower will run as long as it is in the "on" condition and it has no affect on the heat/cooling cycle control. The heat or cooling will cycle on and off with the fan continuously running. The fan is either in the auto or the on position, in "auto" it is controlled by the call for conditioning and the limit switches in the "on" position it runs by passing the other controls but it does not affect the call for conditioning.
    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  5. #15
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    Jul 2009
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    Northeast
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    Default Re: heat system cycling on and off

    That's right but the OP said it works in the on pos. but not the auto pos., clearly sounds like a wiring issue to me. Some units have two transformers, if this one does maybe he should check that

    Then again some say all I know is duct sealing
    Last edited by Sten; 03-07-2010 at 10:53 AM.

  6. #16
    Join Date
    Jun 2007
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    Fayette County, Ohio
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    Default Re: heat system cycling on and off

    Sten,
    Consider this. It is a 3 ton unit hooked to the ductwork in probably a 620 sg.ft. mobile home. The thermostat calls for heat the strips come on and the heat exchanger reaches 80 degrees, the low limit then turns on the fan. With the restricted duct system it would take a while to get much air moving. The heat exchanger reaches say 110 degrees and the high limit opens cutting power to the strips. because the unit is out side and the fan is running it cools below the low limit very rapidly, the fan stops. It then recycles and goes through the same thing.

    With the fan in the on position, the fan is running so when the strips turn on there is enough airflow to prevent the heat exchanger from reaching the high limit.
    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  7. #17
    Join Date
    Jul 2009
    Location
    Northeast
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    661

    Default Re: heat system cycling on and off

    Quote Originally Posted by JLMCDANIEL View Post
    Sten,
    Consider this. It is a 3 ton unit hooked to the ductwork in probably a 620 sg.ft. mobile home. The thermostat calls for heat the strips come on and the heat exchanger reaches 80 degrees, the low limit then turns on the fan. With the restricted duct system it would take a while to get much air moving. The heat exchanger reaches say 110 degrees and the high limit opens cutting power to the strips. because the unit is out side and the fan is running it cools below the low limit very rapidly, the fan stops. It then recycles and goes through the same thing.

    With the fan in the on position, the fan is running so when the strips turn on there is enough airflow to prevent the heat exchanger from reaching the high limit.
    Jack

    Hi Jack
    It seems like your temp diff. is kind of close. When the blower comes on it starts pulling air (some say air can't be pulled), IMHO I don't think it takes so long that it would hit high limit.
    On the other hand, since the unit is a three ton and 1 ton would be good for say 400 sq. ft. depending on area (I'll get flack for that one), it makes me wonder if they have the right sized heating element in there or if it's oversized and putting out to much heat. Then it would hit high limit.

  8. #18
    Join Date
    Mar 2010
    Posts
    3

    Default Re: heat system cycling on and off

    in regard to my heat system cycling, i have solved the problem. i purchased a digital thermastat, programed it so that the thermastat controls the fan instead of the unit controlling it. the heat system is working perfectly now. the thermastat i had on it before was a cheap mechanical thermastat and that seems to be the problem. thank you all for your suggestions.

  9. #19
    Join Date
    Dec 2009
    Posts
    4

    Default Re: heat system cycling on and off

    how do i run my ac after the winter do i need to reset something to get my ac to come on?

  10. #20
    Join Date
    Aug 2007
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    4,045

    Default Re: heat system cycling on and off

    Quote Originally Posted by rdennis View Post
    how do i run my ac after the winter do i need to reset something to get my ac to come on?
    On the thermostat move the mode switch from "Heat" to "A/C"
    "" an ounce of perception -- a pound of obscure "
    - Rush

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