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  • standing pilot going out

    tinkering with an old 80% furnace with a standing pilot, in a rental.

    initial call was for losing the pilot, I replaced the thermocouple, lasted about two weeks. called back for the same problem, relit, lasted a day. replaced the gas valve, lasted 4 days. went back out yesterday checked it all over as best I could, couldn't find a thing, rain cap is in place, furnace seems dry. relit it with another new thermocouple, and it was out again by this morning.

    suggestions?
    No, it's not rocket science, it's plumbing and unlike rocket science it requires a license.

  • #2
    Re: standing pilot going out

    make sure the pilot is hitting the thermocouple
    Charlie

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    • #3
      Re: standing pilot going out

      done, even adjusted the gas to the pilot to get the largest flame possible.
      No, it's not rocket science, it's plumbing and unlike rocket science it requires a license.

      Comment


      • #4
        Re: standing pilot going out

        If it's none of those things you both posted, has it been windy the last few days in your area?

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        • #5
          Re: standing pilot going out

          Is it natural gas is there enough supply as it could be the regulator on the gas meter needing replacement by the gas supplier.

          Tony

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          • #6
            Re: standing pilot going out

            check for a possible short/ grounded wire in the high limit devices.

            has the heater been running or just on standby with pilot and no heat.

            a gas valve and pilot assembly should run assuming it's producing the proper millivolts. check the millivolts with the pilot and gas valve closed and open. you can also disconnect the high limits and see if this changes anything.

            since it's a thermocouple with standing pilot, i'll assume it's not a 24 volt system.

            rick.
            phoebe it is

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            • #7
              Re: standing pilot going out

              If its a forced air furnace have you ruled out a cracked heat exchanger?.

              I would also do a gas manifold pressure test. Watch the flame carefully when it shuts down to see if it extinguishes the pilot. Too high or too low of pressure will suck the pilot out.

              Check for a dirty air filter. Tenants are famous for ignoring those. Clogged filter will steal combustion air.
              Last edited by plumberscrack; 11-15-2010, 12:09 PM.

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              • #8
                Re: standing pilot going out

                I've had the main burner flame lift the pilot burner flame away from the thermocouple causing it to cool and the pilot flame to go out.

                Usually a good cleaning of the burners and crossover tubes will cure the problem.

                Did I ever tell you I hate standing pilot furnaces?

                Is this a Bryant furnace?

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                • #9
                  Re: standing pilot going out

                  good though on the manifold pressure, i'll have to stick the manometer on it

                  very low CO levels at the registers "10ppm" so I don't Believe the exchanger is cracked, though it's something I can explore further.

                  it could be a bryant, it's old and the badging is all long gone. and it has a new filter.
                  No, it's not rocket science, it's plumbing and unlike rocket science it requires a license.

                  Comment


                  • #10
                    Re: standing pilot going out

                    I had an old GM gas boiler in the last house we lived in, same problem. I replaced the thermocouple, gas valve, and a new meter from the gas co.
                    Nothing cracked from the boiler to the chimney cap. Sometimes it would stay lit for 3mos other times 1 heat cycle

                    Comment


                    • #11
                      Re: standing pilot going out

                      I ran into something similar a few years back.
                      air was coming back down the flue and blowing the pilot out.
                      simple fix installed a relight kit and it is still working today

                      http://www.grainger.com/Grainger/ROB...G90?Pid=search

                      Not that exact kit but you get the idea

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                      • #12
                        Re: standing pilot going out

                        Originally posted by MoJourneyman View Post
                        very low CO levels at the registers "10ppm" so I don't Believe the exchanger is cracked, though it's something I can explore further.
                        Any co at the registers is no good. Borrow another co meter and recheck with a nice warm exchanger (fully expanded)

                        The limit thing would only be an issue if it's an ECO. That would interupt the t-couple signal. When it fails, is the pilot out when you get there?

                        The pilot flame should not touch lower than 1/8" from the top of the t-couple. A bigger flame may not be better.

                        A crack is what I would bank on if the mechanicals check out!
                        Look for flame pattern changes when the blower comes on.

                        Give the Model and brand. If it's a standing pilot with an inducer, the dynamic of the answer changes dramatically!

                        Comment


                        • #13
                          Re: standing pilot going out

                          All the suggestions here are excellent. I ve ran into alot of these situations and each solution listed here have all been responsible for my pilot outages in the past. Last week, i was at a boiler and the flame rollout from the combustion chamber knocked out my pilot once. It was a quick flame roll out but managed to knock out my pilot. This flame roll out wasnt evident since there was no blackening on the front. I keep a Honeywell v8200H1236 slow opening one in my van bec i like how it slow opens but not a long term solution for a flame roll out. I might get to change this boiler next march if i m lucky. Double check if you re getting close to 30mv on open test like Rick mentioned. Probably wouldnt bother with a close circuit test since you got a new valve on. These jobs gets me down bec you feel like all your profit is gone with the warrenty. If it was my good customer, i d try to push my Carrier infinity unit. Fun job and good money. Tell them you ll refund all their money back if you opt to go for a new furnace!

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                          • #14
                            Re: standing pilot going out

                            replaced the gas valve again, so far so good.

                            I've honestly never seen a relight kit before.

                            the CO meter is accurate. though that wasn't with the exchanger fully expanded, that was the level I was reading at initial startup.

                            It's a rental, the landlord won't replace it until it catches something on fire.
                            No, it's not rocket science, it's plumbing and unlike rocket science it requires a license.

                            Comment

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