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Lennox Gas Boiler burners not lighting.

Widell4
Widell4 Member Posts: 2
edited November 25 in THE MAIN WALL

I have a Lennox gas boiler with a standing pilot. I noticed pilot was out and re-lit the pilot no problem. Boiler cycled fine for a day, then the burners quit firing. So I replaced the thermocouple with one from Menards. Re-lit pilot then turned main power back on and boiler cycled fine. Two days later same problem. Pilot stays lit but burners quit firing. Turned gas off and lower and reinspected thermocouple. All good. Re-lit pilot and turned power and boiler cycled fine for two days and burners quit working again. Can someone help please as to what is going on and where to start looking? PSI is at 20, pump is working fine. Damper is open.

Comments

  • HVACNUT
    HVACNUT Member Posts: 6,298

    Can you check the milli volts on the thermocouple? It could be the pilot orifice, pilot tube, pilot pressure, gas valve, poor ground, safety that should be manual reset or fusible link, but auto reset, dirty burners, dirty main burner orifices, poor draft, draft damper not closing the end switch...

    Shut off the power and check all the connections. Make sure all Grounds are secure.

    Next time it's running, while the damper is open, there's a little switch where the motor housing meets the actuator plate. Switch it from auto to manual. If the problem goes away, it's an intermittent end switch in the damper motor. If not, it's likely time for a pro.

  • Widell4
    Widell4 Member Posts: 2

    the damper is always open for some reason. So I manually shut it and turned power back on, then manually opened it and the burners still don’t light. I turned damper to auto and still no response to burners. I’m gonna have to wait to check milli volts. I don’t have a meter. But I will tomorrow. Pilot seems strong. And cycling for a few days I think burners would be clear. Can you tell me what these two components are and their purpose and if they could be reason for burners not lighting.

    image.jpg
    image.jpg

  • HVACNUT
    HVACNUT Member Posts: 6,298
    edited November 26

    Top photo is a Spill switch. If it tripped, there's a button between the wires to reset it.

    Bottom photo is the Rollout switch. It's a fusible link so if it blows, it done.

    If at any point you played with the thermocouple without shutting off the power, is it possible the Rollout shorted? I've done it.

    If it wasn't human error and either of those safeties tripped, that makes it not DIY.

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