problem with furnace

[Anonymous-0]

hi guys. my furnace has been tripping flame rollout switch. think it trips when gets to hot where mounted 80'S model HE. elec spark ign. elec Natural gas valve. PVC exhaust. had to reset switch 3 or 4 times in last 11/2 month. fri night tripped again but couldnt reset took apart and apears broken, 2 pc, took them out tried furn again been running since (switch still wired in just missing pieces) other than whole in heat exchange, have 3 co2 dect spread through house. what could be causing it to trip? what are mechanics of this switch? why is furnace working now with pieces missing out of switch? what are dangers of running it like this? any ideas THANKS

 

[DH in Carolina]

Most problems causing a flame roll out switch to trip are: Clogged vent, high winds, burners out of adjustment. Also have seen hole in heat exchanger causing this when blower runs.
Most flame roll out switches have a normaly closed set of electrical contacts and a thermal disk which opens the contacts when the temperature exceeds the disk setting. If you removed the disk or the actuator rod the contacts will never open.
The danger of running it like this is you could burn your house down because you have bypassed a safety control. Flame roll out switches are cheap and can be bought online or at a heating supply store. They are different temperatures. Please get it fixed. DH

 

[rocko]

Thanks DH. I had though of that myself and have there for only been running it when at home. shut it down at night and or if going out. plan on getting new one but didnt want to pay OT rates. stores closed today. holiday up here. think it may have been PVC vent with condensate in it. doing some renos and took 2 clamps off. think it had low spot and think hear liquid running back last night when rehung it. was also very windy that night. dont think i have hole in heat exchange as co2 detectors have been bussing but think i should also check that out. any suggetion on best way to do so. also think flames may need adjusting as have yellow flicking at times but air adjustments dont seem to make any diff.

Thanks for the info

 

[DH in Carolina]

If you have a pvc vent water may have got in the tubes where the flame burns. Tie a rag on a coat hanger and push it down the burner tubes and see if any water in there. A frozen drain trap will also cause water in the burner tubes with a furnace in a attic. Should call them heat exchanger tubes instead of burner tubes. DH

 

[rocko]

Thanks again DH. ill give that a try also.

 

[old1850d]

Depending on what brand you have it might me a case of the secondary heat exchanger being plugged or even having a hole in it not pulling the exhaust thru the furnace properly causing ecsesive heat build up tripping of the rollout switch ,do not run this furnace this way