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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 8679
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I have an old (1968ish) Lennox G8-95T furnace and I am

Customer Question

I have an old (1968ish) Lennox G8-95T furnace and I am trying to source a part that looks similar to the thermal coupler, it is similar in length and has the copper line. It screws on to the side of the pilot box assembly. Pilot light won't stay lit after waiting 90 seconds. I replaced thermal coupler, still have the same problem. I believe the part in looking for is a flame sensor?? Not sure if this is tge problem.
Submitted: 2 years ago.
Category: HVAC
Expert:  Phil replied 2 years ago.


Thermocouples are the flame sensors in these older furnaces... a flame sensor rod is only used with much later furnaces, starting in the 1980's that have electronic controls.

Try tightening the nut that attaches the thermocouple to the gas valve another 1/4 turn or so, if that fails and you are sure the nut is quite snug, and the pilot flame is robust onto the tip of the new thermocouple, the gas valve solenoid is likely bad. The solution is to replace the gas valve, the solenoids are no longer sold separately (its a safety issue).

You could test the gas valve with this but cost is more than a new gas valve, and the valve on a late 60's furnace is well beyond the typical life span.

You can get a new gas valve at they are Lennox specialists, they only need the furnace model number as a rule, but have all of the numbers on the gas valve itself available also.


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