SkiFletch
New member
At the risk of borrowing Cully's thread title, need a little furnace troubleshooting help. I have a Lennox G40UH-36A-070-15 furnace for my owners half of the duplex that has been acting up on me recently. Occasionally the past few weeks I would come home to no heat with the thermostat calling for it. A quick off/on and it would fire right back up. Well the problem has gone from intermittent to more frequent so I've gone searching for the issue and I THINK I've got it figured out, but wanted to check with some others on this.
Today I had the foresight of looking at the blinky LED codes (maybe I should have thought of that sooner :headwally: )to find out what the error was. It says either "A: Lost flame sense, or B: Burner failed to ignite after 4 attempts during startup." Sure enough when I powered on/off I got to watch it go through and send the error back. The blower(s) fire up, little electric pilot heats up/glows red, gas valve clicks open, nice good flame start for about 5 seconds, then the gas valve shuts off, flame stops. Repeats 3 times, then kicks out the error code. A few more on/off starts by me later and it eventually does stay on. And it's currently been through a few cycles properly since then with the thermostat calling for heat and it actually staying on.
So my thought is that the flame sensor thermocouple is on it's way out. Seems pretty straight forward thing to replace. I'm told Belknap has parts for Lennox furnaces, but I was hoping someone had a solution that was less-far for someone in North Buffalo. Should I be replacing some other part, or is it likely the relatively cheap thermocouple?
Thanks for the help
Today I had the foresight of looking at the blinky LED codes (maybe I should have thought of that sooner :headwally: )to find out what the error was. It says either "A: Lost flame sense, or B: Burner failed to ignite after 4 attempts during startup." Sure enough when I powered on/off I got to watch it go through and send the error back. The blower(s) fire up, little electric pilot heats up/glows red, gas valve clicks open, nice good flame start for about 5 seconds, then the gas valve shuts off, flame stops. Repeats 3 times, then kicks out the error code. A few more on/off starts by me later and it eventually does stay on. And it's currently been through a few cycles properly since then with the thermostat calling for heat and it actually staying on.
So my thought is that the flame sensor thermocouple is on it's way out. Seems pretty straight forward thing to replace. I'm told Belknap has parts for Lennox furnaces, but I was hoping someone had a solution that was less-far for someone in North Buffalo. Should I be replacing some other part, or is it likely the relatively cheap thermocouple?
Thanks for the help
