OLD Lennox furnace pilot not staying lit - http://www.hvacmechanic.com/ Forums
Original message
| scombs
 |  "OLD Lennox furnace pilot not staying lit"
, posted Sat 9 Feb 22:07  
I have an old Lennox furnace that I believe may be original to my house. I'm not sure how old it is. It is Lennox model G8Q2-110C. The pilot light won't stay lit. I have followed the instructions on the inside panel to relight the pilot by:
1 - Holding down the knob in 'pilot' position while lighting the pilot light and keeping it held down for 60 seconds.
2 - The instructions then say to rotate the knob to the 'on' position but when I let up on the knob from 'pilot' to turn it to 'on' the pilot light just goes out and stays out.
I do not know anything about my furnace except how to light the pilot. I googled my model number and found this website. Before I call the repair guy and spend a bunch of $ I can't afford (which I'm probably going to have to do anyway because I'm a complete moron when it comes to HVAC stuff) - can anyone give me an idea if this is something I can fix/replace myself?
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Replies:
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| jbwstroker
| "Re(1):OLD Lennox furnace pilot not staying li" , posted Sat 9 Feb 22:32
Sounds like the thermocouple needs to be replaced. Shouldn't be too difficult to replace and not too expensive to have done. If you aren't comfortable doing it yourself, call your service company. Repair cost (including service call) could be anywhere from $100-150 or so, excluding after hours or weekend service rates and depending on your region.
"I'd probably be considered an old wise man if I could only remember everything that I've learned".
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| | scombs
| "Re(2):OLD Lennox furnace pilot not staying li" , posted Sat 9 Feb 22:39
Thanks for the quick response. Is the thermocoupler hard to replace? If I've got decent instructions or if it's relatively simple to do I can do it myself (assuming that it actually is the thermocoupler that's bad).
I have done just about everything in my house, repairwise, except replacing the main electric panel and having to replace major plumbing. Everything else though, I've done myself - basic wiring, fixtures, drywall, roof, etc. So I'm not all thumbs.
If replacing the TC isn't too bad I can give it a shot. Do you think that someone with zero experience with such things would be better off just payin for the service guy to do it? I wouldn't want to make it worse and pay more in the end to undo what I did.
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| | jbwstroker
| "Re(3):OLD Lennox furnace pilot not staying li" , posted Sat 9 Feb 22:52
It's a rather easy job for an experienced tech. On some models you can remove the thermocouple from the pilot assembly without removing the assembly bracket. If there's space below the bracket for the thermocouple to slide out, you can usually remove it by grabbing the base of the TC with needle nose pliers and sliding it out, making sure not to bend the pilot assembly bracket thus misaligning it. Of course make sure to turn off the gas supply to the furnace before doing this. If you can achieve this without much difficulty you should be okay. Unscrew the opposite end of the TC from the gas valve where it attaches. Install the new TC in the bracket making sure to note the alignment of the one you just removed. The tip of the TC should be covered by approx. 1/4" of the pilot flame. When screwing the new TC into the gas valve, make sure not to cross-thread it. Tighten it as much as possible by hand, then about 1/2 turn by wrench. On some models removing the pilot bracket and pilot tube from the gas valve will be neccesary. If this is the case with your furnace, I would strongly urge you to leave it to a pro. You can probably pick up a replacement TC at Home Depot or Lowes. A 24" length will be adequate in most cases.
"I'd probably be considered an old wise man if I could only remember everything that I've learned".
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| | jbwstroker
| "Re(4):OLD Lennox furnace pilot not staying li" , posted Sat 9 Feb 22:56
PS: I'm pretty sure the TC is your problem. I'd be willing to bet my wife on it (but not my house). :)
"I'd probably be considered an old wise man if I could only remember everything that I've learned".
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| | scombs
| "Re(5):OLD Lennox furnace pilot not staying li" , posted Sat 9 Feb 23:12
Thanks for the info and the advice. I think that it's best if I leave it to a pro this time. The furnace is so old that if there was even a remote possibility that I could screw it up - I'd do it. I'm just lucky like that I guess.
$150 is going to hurt. But at least I have a home that I own. There are worse fates in this world.
Thanks again for your help. I'm definitely going to bookmark this site!
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| | jbwstroker
| "Re(6):OLD Lennox furnace pilot not staying li" , posted Sat 9 Feb 23:19
I'd call and ask them the question "IF it is the themocouple how much will the repair be?" (Including service call). If they refuse to give you the price over the phone, I'd call someone else. If you get an answering service, ask them to have the on-call tech call you first and see if he will quote you a price. Good luck.
"I'd probably be considered an old wise man if I could only remember everything that I've learned".
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| | scombs
| "Re(7):OLD Lennox furnace pilot not staying li" , posted Sun 10 Feb 13:09
I went to HD and bought a universal thermocouple - 36" which as it turns out was the same length as the old one. I did have to unhook the assembly to get to the old one, but I was able to do it and replace the TC.
Went through all of the pilot light start up instrux again, and I've got the same problem - the pilot light stays lit when I've got the selector knob at the 'pilot' position and I have to hold the button down for 60 seconds. As soon as I let up on the knob (which you have to do to move it from the 'pilot' position to the 'on' position) the pilot light goes out.
Help?
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| | jbwstroker
| "Re(8):OLD Lennox furnace pilot not staying li" , posted Sun 10 Feb 15:53
It's a good thing I only bet the wife :( Usually this problem IS the TC, but not always. Are you sure you have the new TC properly aligned with the pilot flame? (should engulf approx 1/4" above the tip of the TC). Is the pilot flame sharp and blue or lazy and yellow? Did you remember to tighten the TC properly into the gas valve? If everything here seems ok, then it's likely a bad gas valve.
"I am not responsible for mistakes other than my own. If in doubt call a pro!"
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| | scombs
| "Re(9):OLD Lennox furnace pilot not staying li" , posted Sun 10 Feb 16:12
Had to call the service guy today (Sun 10th) as the part of KY that I'm in calls for 10 degrees or lower tonight. Didn't want to take the chance of busting any of my pipes so I called em.
Turns out it was the gas valve Considering that there's only 3 pieces to a furnace you had a 1/3 chance of guessing without lookin at it.
The universal valve that I'm having put on (right now as a matter of fact) is gonna run me $100. Plus the 'Sunday' call - all said and done about $230. Ouch. But, like I said it's better than having my pipes freeze on me tonight and having to deal with that too.
I appreciate your help anyway. I've still bookmarked this site and I'll let any of my friends know to ask questions.
bet the wife.. that's funny... :)
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