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-   -   Bryant furnace turns flame off before set temperature is reached. (https://www.askmehelpdesk.com/showthread.php?t=776608)

  • Nov 25, 2013, 06:00 PM
    aweimer
    Bryant furnace turns flame off before set temperature is reached.
    I have a Bryant Induced-Combustion Gas Furnace, model 373LAV Downflow & 383HAV Upflow. Mounted horizontally. It turns off flame before set temperature is reached, and recycles immediately.

    Sequence is:

    Inducer starts
    After 25 sec. the ignitor glows
    After 8 sec. the flame lights
    After 45 sec. the blower fan starts
    After 2 min. 21 sec. the flame goes out
    Indicator light flashes 33
    After 5 sec. the inducer fan stops
    After 3 min. 58 sec. the blower motor stops
    Inducer starts immediately
    And it's the same cycle over again.

    Clean filter, and no intake restrictions.
    Doesn't appear to be cracked heat exchanger (no blowback)
    Flames are blue and appear to be confined to the exchanger ports (no roll-out)
    Thermostat anticipator has not affect
    RobertShaw mercury switch thermostat level

    I cannot inspect the vents close-up, they are in high ceiling. But, I cannot detect much air from the vents.

    It is 20 degrees F outside. The thermostat is set to 72, but the temperature does not get above 64.

    What do you think?
  • Nov 25, 2013, 07:26 PM
    ma0641
    You show a model for upflow and downflow but have it mounted horizontally? Is it rated for horizontal applications? Some are and some aren't. Heat exchangers may be laid out differently. Could be overheating and the thermal overload is shutting down the gas. From your description of operation, it sounds like it is operating properly. I also noted your "low airflow" comment. If you have a collapsed or restricted duct, that will also trip the thermal overload due to an overheated plenum.

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