pilot light won't stay lit
#1
04-10-04, 05:12 PM
pilot light won't stay lit
Have an old furnace. Over 40 years old. All of a sudden, the pilot light cuts out. Can get it lit, but won't stay lit.
1) any hints on what i should replace? should i just replace the whole pilot assy?
2) there are two metal pipes running to pilot.
one narrow copper pipe going directly to it and one aluminum pipe right next to it. i'm pretty sure the copper one is gas, but i'm not sure. does anyone know?
thanks
fdonger
1) any hints on what i should replace? should i just replace the whole pilot assy?
2) there are two metal pipes running to pilot.
one narrow copper pipe going directly to it and one aluminum pipe right next to it. i'm pretty sure the copper one is gas, but i'm not sure. does anyone know?
thanks
fdonger
#2
04-10-04, 05:30 PM
one narrow copper pipe going directly to it
one aluminum pipe right next to it.
turn power on gas on and light the pilot again should hold for you.
ED
#3
04-11-04, 12:13 PM
ok...
i replaced the thermocouple/pilot assy. turned gas and power back on. tried to light the pilot.
i had the pilot knowb depresssed for a few minutes and the pilot wouldn't stay lit.
1) do i need to light it and hold it for a long time initially?
2) i would think lighting the pilot would be independent of anything else in the system. is that true?
am i missing something?
donger
i replaced the thermocouple/pilot assy. turned gas and power back on. tried to light the pilot.
i had the pilot knowb depresssed for a few minutes and the pilot wouldn't stay lit.
1) do i need to light it and hold it for a long time initially?
2) i would think lighting the pilot would be independent of anything else in the system. is that true?
am i missing something?
donger
#4
04-11-04, 12:26 PM
maybe i don't understand how a pilot light stays lit.
i didn't think this was the case, but does a consistent input of gas keep the pilot light lit? if so, then there is a feedback mechanism through the thermocouple that keeps the gas on when i let the pilot knob release.
if i've replaced the pilot thermocouple assy and it won't stay lit, it must be the control unit that's bad.
am i on the right track?
donger
i didn't think this was the case, but does a consistent input of gas keep the pilot light lit? if so, then there is a feedback mechanism through the thermocouple that keeps the gas on when i let the pilot knob release.
if i've replaced the pilot thermocouple assy and it won't stay lit, it must be the control unit that's bad.
am i on the right track?
donger
#5
04-11-04, 01:51 PM
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Hello: donger
Before assuming the control is defective, try another thermocouple. New ones can be defective.
Also try cleaning the end of the T-Couple and the inside upper end inside the control. Use nothing but a cotton swab. No chemicals, etc.
Be sure the element end of the T-Couple in the pilot assembly is correctly in place. Only the tip of the T-Couple is to be heated. About a 1/4 inch of the tip.
The heat the pilot flame provides to the T-Couple allows the T-Couple to generate a small amount of dc volts. About 1/4 volt. Which is used by the magneto inside the control to hold the tiny pilot gas valve opened.
Before assuming the control is defective, try another thermocouple. New ones can be defective.
Also try cleaning the end of the T-Couple and the inside upper end inside the control. Use nothing but a cotton swab. No chemicals, etc.
Be sure the element end of the T-Couple in the pilot assembly is correctly in place. Only the tip of the T-Couple is to be heated. About a 1/4 inch of the tip.
The heat the pilot flame provides to the T-Couple allows the T-Couple to generate a small amount of dc volts. About 1/4 volt. Which is used by the magneto inside the control to hold the tiny pilot gas valve opened.
#6
04-12-04, 10:08 AM
thanks sharp advice.
i'm glad u bring it up. the tip isn't positioned very well in relation to the gas valve. the flame is definitley not hitting the top 1/4" of the tip. i tried repositioning, but to no avail. looks like i will need to get a new fixture for the gas valve/thermocouple. i didn't see these at the home depot.
i guess i'll try some specialty shop.
i did get a longer thermocouple as well. you think this will make a difference? i figure as long as the connection is there, it would be okay.
donger
i'm glad u bring it up. the tip isn't positioned very well in relation to the gas valve. the flame is definitley not hitting the top 1/4" of the tip. i tried repositioning, but to no avail. looks like i will need to get a new fixture for the gas valve/thermocouple. i didn't see these at the home depot.
i guess i'll try some specialty shop.
i did get a longer thermocouple as well. you think this will make a difference? i figure as long as the connection is there, it would be okay.
donger
#7
04-12-04, 10:18 AM
the flame is definitley not hitting the top 1/4" of the tip. i tried repositioning, but to no avail.
ED
#8
04-13-04, 01:50 PM
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if the pilot orifice is dirty, it will make a BIG diffefence on how well the flame hits the thermocouple. i would clean it and try again. at 40 yrs old, those parts are brittle, be very careful, or just replace the pilot assy, which is what i would do.
