Results 1 to 6 of 6
  1. #1
    Join Date
    Jan 2005
    Location
    Columbia, Mo GO, TIGERS
    Posts
    893

    unplug hose from furnace pressure switch, hook to magnehelic, then blower on high...

    and as the blower spools up, the hose on magnehelic positive pressure port yields needle movement every time.

    what's going on?

    A. Wasting time.

    B. Checking heat exchanger.

    C. Other

  2. #2
    Join Date
    Jan 2011
    Location
    TN
    Posts
    93
    does the needle hold when blower is running? I would go with heat xger

  3. #3
    Join Date
    Jan 2005
    Location
    Columbia, Mo GO, TIGERS
    Posts
    893
    yes, steady needle until blower power is cut. then needle returns to zero.

  4. #4
    Join Date
    May 2000
    Location
    Urbandale IA. USA
    Posts
    4,805
    Is the blower compartment OPEN to the room, SUCKING from the space and then down the flue?
    Is this sealed combustion heating?
    .
    Those who dance, appear insane to those who do not hear the music.
    Those who believe, appear ignorant to those who do not know God.

  5. #5
    Join Date
    Jan 2005
    Location
    Columbia, Mo GO, TIGERS
    Posts
    893
    furnace in basement is an OLD upflow ninety percenter, one pipe out the rim joist and the brick veneer.

    burner openings are like an eighty percenter, no sealed burner box.

    the blower compartment door is a mite loose, it bangs audibly shut as the blower suction develops. (that would drive me nuts, and that's only a short walk from here.)

    my helper said the furnace is a Magic Chef brand. ummm, BARBEQUE!!!!!!!!!!

  6. #6
    Join Date
    Apr 2011
    Location
    Coastal Maine
    Posts
    769
    I would look for a crack on the HX.

    Good Luck.

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