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  1. #1
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    Default furnace will not shut off

    I ran into an electric furnace today that will not shut off. It is central forced air, and it would not shut off if the temperature was met, so I switched the system off, and it wouldnt stop blowing hot. Finally had to shut it down at the panel, but was wondering if anyone had an idea as to the cause.

    Thanks for any help,

    Drew McGee

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  2. #2
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    Default Re: furnace will not shut off

    Its been awhile, but possibly the sequenser (which sequenses the heat strips) or a contactor??

    Paul Kondzich
    Ft. Myers, FL.

  3. #3
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    Default Re: furnace will not shut off

    Quote Originally Posted by Drew McGee View Post
    I ran into an electric furnace today that will not shut off. It is central forced air, and it would not shut off if the temperature was met, so I switched the system off, and it wouldnt stop blowing hot. Finally had to shut it down at the panel, but was wondering if anyone had an idea as to the cause.

    Thanks for any help,

    Drew McGee
    I would be betting on a bad thermostat.
    Was the system running before you broke it?
    I hope you told the homeowner that you shut down the system.....

    Scott Patterson, ACI
    Spring Hill, TN
    www.traceinspections.com

  4. #4
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    Default Re: furnace will not shut off

    Quote Originally Posted by Drew McGee View Post
    I ran into an electric furnace today that will not shut off. It is central forced air, and it would not shut off if the temperature was met, so I switched the system off, and it wouldnt stop blowing hot. Finally had to shut it down at the panel, but was wondering if anyone had an idea as to the cause.

    Thanks for any help,

    Drew McGee
    Drew,

    How long did the blower run after the temp was met / switched off ?

    It Might have Choked Artie But it ain't gone'a choke Stymie! Our Gang " The Pooch " (1932)
    Billy J. Stephens HI Service Memphis TN.

  5. #5
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    Default Re: furnace will not shut off

    The system was on, but I lowered the temp. I prefer the term 'failed under test', but the seller is aware of the situation.

    The system ran for around 30 minutes, but it was more than the blower, the strips were hot the entire time, even after it was off at the thermostat.


  6. #6
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    Default Re: furnace will not shut off

    Sequencer failure, very common failure on electric furnaces.
    A thermostat failure is not likely if you used the system switch (Heat, Off, Cool) after turning the temperature back to normal.

    Jim Luttrall
    www.MrInspector.net
    Plano, Texas

  7. #7
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    Default Re: furnace will not shut off

    Thanks for all your answers


  8. #8
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    Default Re: furnace will not shut off

    Quote Originally Posted by Scott Patterson View Post
    I would be betting on a bad thermostat.
    Was the system running before you broke it?
    Scott, you crack me up.

    Department of Redundancy Department
    Supreme Emperor of Hyperbole
    http://www.FullCircleInspect.com/

  9. #9
    Jim Zborowski's Avatar
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    Default Re: furnace will not shut off

    Is the fan switch set to "run" or "AUTO'?


  10. #10
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    Default Re: furnace will not shut off

    Quote Originally Posted by Jim Zborowski View Post
    Is the fan switch set to "run" or "AUTO'?
    Jim,

    That was my thought too, and (I suspect) that of Billy when Billy asked "How long did the blower run after the temp was met / switched off ?".

    Drew said "The system ran for around 30 minutes, but it was more than the blower, the strips were hot the entire time, even after it was off at the thermostat."

    That would not be the fan set to 'On' instead of 'Auto'.

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

  11. #11
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    Default Re: furnace will not shut off

    Quote Originally Posted by Drew McGee View Post
    I ran into an electric furnace today
    Like Scott said, you broke it man.

    You really need to stop running into things like that.

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

  12. #12
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    Default Re: furnace will not shut off

    Quote Originally Posted by Jerry Peck View Post
    Jim,

    That was my thought too, and (I suspect) that of Billy when Billy asked "How long did the blower run after the temp was met / switched off ?".

    Drew said "The system ran for around 30 minutes, but it was more than the blower, the strips were hot the entire time, even after it was off at the thermostat."
    .

    I was thinking cool down period, my money is on the Limit Switch.

    It Might have Choked Artie But it ain't gone'a choke Stymie! Our Gang " The Pooch " (1932)
    Billy J. Stephens HI Service Memphis TN.

  13. #13
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    Default Re: furnace will not shut off

    The limit switch is a safety that never comes into play unless the furnace is on a runaway. The blower and heat strips continuing to run could be stopped by the limit switch if there was too much heat, but that would only occur if the normal operating control is broken.
    Sequencer switch is the culprit.

    Jim Luttrall
    www.MrInspector.net
    Plano, Texas

  14. #14
    Jim Zborowski's Avatar
    Jim Zborowski Guest

    Default Re: furnace will not shut off

    OK, I missed that. Thought he said the blower wouldn't stop.


  15. #15
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    Default Re: furnace will not shut off

    Quote Originally Posted by Jim Luttrall View Post
    The limit switch is a safety that never comes into play unless the furnace is on a runaway.
    .
    Sequencer switch is the culprit.
    Either way time for The Trades.

    It Might have Choked Artie But it ain't gone'a choke Stymie! Our Gang " The Pooch " (1932)
    Billy J. Stephens HI Service Memphis TN.

  16. #16
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    Default Re: furnace will not shut off

    Either way time for The Trades.
    Agreed.

    Jim Luttrall
    www.MrInspector.net
    Plano, Texas

  17. #17
    Join Date
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    florida
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    Default Re: furnace will not shut off

    Thanks again. By The Trades, are you saying its time to call in a service tch?


  18. #18
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    Default Re: furnace will not shut off

    Yes, "Trades" would mean someone specifically trained in one of the specialties such as A/C, Electric, Plumbing.

    Jim Luttrall
    www.MrInspector.net
    Plano, Texas

  19. #19
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    Default Re: furnace will not shut off

    Thanks. That was my initial call,I was just trying to get a handle on the cause.


  20. #20
    TOM DEEHAN's Avatar
    TOM DEEHAN Guest

    Default Re: furnace will not shut off

    Quote Originally Posted by Billy Stephens View Post
    I was thinking cool down period, my money is on the Limit Switch.
    If the limit had tripped (over heat condition) and the heat strips were still running, that sounds like a melt down. Better call the HVAC guy.


  21. #21
    TOM DEEHAN's Avatar
    TOM DEEHAN Guest

    Default Re: furnace will not shut off

    [quote=Drew McGee;31082]I ran into an electric furnace today that will not shut off. ]

    Did you have the right thermostat?


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