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  1. #1
    Join Date
    Jan 2008
    Location
    East berlin, PA
    Posts
    293

    Heat N Glo Model 36DV88- pilot goes out on High Limit

    I have a customer with one of these gas fireplace inserts. Looks to be about 20 years old. Every time he fires it up it runs for a while then shuts the pilot off. I stopped over to take a look, and the high limit kills the pilot. This does not have a circulator fan. I checked and it does not appear the flue is clogged, because I can feel plenty of heat coming out... Should this thing be able to run without a circulator fan and not go out on the high limit? There does not appear to be any thermostat.

    The owner said it was that way when he moved in about 15 years ago...


    Is there anything else I can check or is something not working that should be that I don't know about?


    He doesn't have the manual any more and all I can find at heat n glo is a parts book...


    Is there a circ fan available for this?

    Thanks
    "Delay is preferable to error"- Thomas Jefferson

  2. #2
    Join Date
    Aug 2004
    Location
    S.E. Pa
    Posts
    6,300

    Cool

    The gasket is probably bad on the glass causing heat to spill into that upper left corner where the spill switch is. HG issued a soft recall on their original glass with the red silicone rubber gasket. These glass panels should be replaced with new glass that has the black fiberglass rope gasket even if the rubber gasket appears to be intact. Note that sometimes the gasket itself is intact but not adhered to the glass. Also check the tension on the wing nuts & clips that retain the glass.

    With the unit cold, you should be able to play a chemical smoke puffer around the perimeter of the glass without smoke entraining into the firebox behind the glass. If it does, you have located a breach in the seal. Look at the paint around the breach point--it will be a light gray if heat from the firebox has been escaping.

    regardless, you should have a qualified pro inspect and service that unit.
    HTH

  3. #3
    I agree with Hearthman, I would check the glass seal as pretty much every old red silicone gasket glass is shot by this time. If it is still the red silicone gasket I would recommend changing it even if you don't detect leaks because it is definitely a weak point.
    I haven't worked on one of these for a little bit but I seem to remember
    Heat-n-glo changing the original hi-limit switch which was "normally closed" to a groundable hi-limit which was "normally open" and grounded out the valve when tripped as a replacement

  4. #4
    Join Date
    Aug 2011
    Location
    Ontario
    Posts
    381
    What ??????????? A normally open switch.
    There is no bad beer, some just taste better than others.

  5. #5
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    394
    Quote Originally Posted by talktowags View Post
    What ??????????? A normally open switch.
    Yes, it closes and causes the valve to ground out and shut off when it over heats.
    Common sense is NOT common !!!

  6. #6
    Join Date
    Aug 2011
    Location
    Ontario
    Posts
    381
    Quote Originally Posted by logdoc_rob View Post
    Yes, it closes and causes the valve to ground out and shut off when it over heats.
    Worked on h&g but never seen that switch. N/O or N/C limit, if it shutting down unit than something is causing it to overheat. Or bad switch.
    There is no bad beer, some just taste better than others.

  7. #7
    Join Date
    Aug 2004
    Location
    S.E. Pa
    Posts
    6,300

    Cool

    When you have a high limit tripping out, you must conduct a comprehensive diagnosis. Check the venting for obstruction, proper configuration, termination, etc.
    Check the gas pressures, inlet and manifold. Gauge the burner orifice. Try to determine if it has the correct burner and air shutter setting. Verify log and ember placement.

    Those high limit switches were discontinued back in the mid-90s. You can tell a NO by the rubberized coating and leads to TH. There is a short jumper ground wire.

    On a B-vent fireplace, never modify or alter the spill switch. A spill switch tripping on a draft hood requires an urgent diagnosis by a pro.

  8. #8
    hearthman: i have a heat and glo 6000 tv - the glass has the red seal and seal has two large gaps - do you think i would be covered under the "soft" recall for this glass on this model - i too have had pilot light problems but have replaced the limiter switch and so far so good ...
    thanks
    davey jones

  9. #9
    to add: the swtich/diag was done by a professional - i'm now just concerned with the glass issue ...
    again, thanks
    davey jones

  10. #10
    Join Date
    Aug 2004
    Location
    S.E. Pa
    Posts
    6,300

    Cool

    Most of the old TVs came with deliberate gaps in the gaskets. Note, the high limit switch for a TV is not the same as for a DV. Some of those TVs were so prone to tripping the high limit switch, the factory made a different bracket that moved the switch about 1/4" away from the opening of the draft hood.

    Contact HG Tech support with model and serial # to ensure you get the correct glass and high limit switch. As usual, I recommend a qualified pro service it.

  11. #11
    thanks for your prompt reply ...
    davey jones

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