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so-elitecrete 11-18-2007 08:12 PM

smell'd odor of natl gas after,,,
replac'd a bad thermocouple today,,, remov'd pilot lite supply line to get my meathook position'd to replace the t-cple,,, new t-cple installed, tried to rethread the supply line but but it x-thread'd,,, not realizing my error, started furnace back up & everything's fine 'cept for the gas odor :-(,,, removed line & re-install'd correctly but there's still the odor (probably from damag'd threads even under lo-pressure.

there was a coupling washer which was reinstall'd,,, 1, is that a 'crush' washer ONLY to be used once &, when removed as above, a NEW 1 must be used; 2, can i rethread w/tap & all will be well ( unless i still small gas, of course ! ); 3, pipe dope help / hinder / not to be us'd on alum gas valve ?; or 4 [ absolute downside ], replace gas valve AND pilot supply line ?

there are only things i can conjure up so need a pro's advice,,, all jokes, slurs, & insults weather'd w/o chagrin,,, funny - for a $9 t-couple, could be looking at $500 ( svce & parts ) if i can't fix this,,, promise - if this is above my ability, i'll call my local pro,,, bwt, the gas valve's an essex in a lennox.

BEFORE ANYONE CALLS OR HAS A HEART ATTACK, THE BLK PIPE SUPPLY LINE PETCOCK'S OFF along w/elec power ! ! !,,, thanks in advance, guys !

fireguy 11-18-2007 08:47 PM

Replace the thermocouple. Do not use pipe dope on the thermocouple. Pipe dope insulates the thermocouple from the gas valve. the thermocouple generates milli-volts, you just prevented the mill-volts from opening the solenoid. I don't know if you can clean the pipe dope from the gas valve. Make sure that 1/3 to1/2 of the thermocouple tip is in the flame.

Don't use pipe dope on the thermocouple.


so-elitecrete 11-18-2007 09:23 PM

the t-couple's fine,,,
fireguy - install'd AND working properly,,, understand dope's interference w/elec circuit,,, & there's no dope on the gas valve, either,,, i'm wondering IF its possible to do so on the pilot lite supply line OUT of the gas valve.

thanks for the prompt reply - now i'm going to bed ;-)

sams7267 11-19-2007 07:55 PM

yes use pipe dope on the gas line fittings.
yes use new crushwashers.

After you are certain your handywork is not leaking and the area is free of gas... try it.

If you still smell gas it's likely from "roll off". Gas not burnt at ignition, usually caused by dirty burners.

so-elitecrete 11-20-2007 06:10 AM

sammy, you're the MAN !!!
here's the plan when i get back to the house next week,,, 'chase' the threads w/tap VERY carefully trying to prevent chips from entering the pilot light supply line,,, the gal valve's alum but, since the male fitting's steel, that part should be ok,,, lite coating of dope & new crushwasher,,, rethread & tighten but NOT overtighten,,, let sit o'nite & start 'er up again.

burner's flame's fine & have never had the residual "roll off",,, if this doesn't work, call the pro & laugh at myself.

thanks, sammy ! ! !,,, you're great & i do appreciate the response.

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