20 minutes later it shuts off

[dynamic098]

I am working on a Lennox FP and the complaint is that the FP goes out after 20 minutes or so. Sure enough, I turn it on and read the paper, 20 min or so later off it goes. I hit the wall switch and restart it and agin 20 minutes later, out she goes. What gives ??

[gasguy]

What are your MV doing when the burner is running? Have you checked that the venting is clear and it's not tripping a limit? Look at the pilot flame when the main burner is running. A couple of issues I've seen are that the air being drawn into the unit pushes the pilot flame away from the t-pile and drops the MV enough to drop the main burner. I've had to make a small sheet metal shield to keep the draft off the pilot. Another issue is a restriction in the gas supply so when the main burner comes on the pilot flame shrinks a little and gives the same result. Also check that all the wiring connections are clean and tight. As they heat up and expand they could cause a poor connection.

[darthvader]

Or it is probably a dirty pilot

[BigBacardi]

lol...see the other thread...

i bet one dollar and 24 cents.....decora switch on wall...use toggle and all will be good...