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Odd ignition failure - temporary fixed by turning gas main off/on.

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RemoteRoads
RemoteRoads Member Posts: 4
edited December 2025 in Gas Heating

We have a single ~100kBTU direct vent propane hot water heater that supplies domestic hot water as well as radiant heating through an exchanger. We are experiencing an intermittent error for the past week where the tank will throw an ignition failure code "The control has not detected proper flame detect signal to transition in heating mode. The control requires above approximately 1uA current to verify proper flame".

I have replaced the ignitor (a real pain as it is buried in the center of the tank and requires removing the entire direct vent system to access from the top down) several times in 11 years with the most recent being 10 months ago.

All attempts to power cycle the tank (including breaker main) resulted in the same error.

However - turning off the propane supply and immediately turning it back on and powering up the tank fixes the issue for a day or two.

Temperature was -4F/-20C when it first started and is now -25F/-32C. We have had issues with propane pressure when temperatures reach -40/-40 but that throws a different error. 1000gallon tank and issue started happening at 35% and still happening after fill (85%) this week.

Any thoughts, hints or prayers would be welcome in diagnosing.

Comments

  • GGross
    GGross Member Posts: 1,735

    What's the model of the unit?

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 19,721

    Could be moisture in the propane tank icing up the regulator. Propane starts out as liquid. When the pressure is reduced it flashes into a gas and acts just like a refrigerant and it boils off it can freeze any moisture in the pipe or regulators. It usually happens in the regulators as that is where the pressure drop is. Shutting of and turning on the gas maybe unsticking the regulator.

    Its a guess but it is possible.

    RemoteRoadsmattmia2
  • RemoteRoads
    RemoteRoads Member Posts: 4
    https://forum.heatinghelp.com/discussion/comment/1876906#Comment_1876906

    Envirosense Direct Vent - Propane (Some material refers to it as "John Woods" instead of Envirosense but its never consistent)

    Model 6G50100PPDVH05 125

  • 109A_5
    109A_5 Member Posts: 3,538

    Can't find a 125 manual. Does it have a low gas pressure switch ? The online 130 manual and others, the wiring diagram has horrible resolution.

    Were all these items checked or verified?

    image.png
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • mattmia2
    mattmia2 Member Posts: 15,739

    could be the vent is icing over on the regulator too.

  • RemoteRoads
    RemoteRoads Member Posts: 4
    https://forum.heatinghelp.com/discussion/comment/1876991#Comment_1876991

    I'll re-check the exterior regulators and intake for new ice build up. Its getting worse, instead of a day between issues, its now only a couple of hours (or less) before I have to turn off/on the gas again.

    https://forum.heatinghelp.com/discussion/comment/1876990#Comment_1876990

    Checked the wires no issues.. Reluctant to check the flame sensor and burner until I've exhausted the other external options. Unit is aging so I try limiting how many times I jump inside it. I'll pull it apart tomorrow. Thank you.

  • mattmia2
    mattmia2 Member Posts: 15,739

    water is also a common problem as @EBEBRATT-Ed said. they put alcohol in the tank to keep it from freezing but at sub zero temps the concentration may not be high enough to keep it from freezing

    RemoteRoads
  • psb75
    psb75 Member Posts: 1,103

    Regulators can freeze up too. I have warmed some with a heat gun.

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