roll out switch

[frostedfingers101]

ok guys, not sure if what i did was right, so any info would be greatly appriciated. i was on an Air-Pro furnace M# AF80MPA07583 S# 4601A01129 i have found its made from lennox, but anyway, i found roll out switch open, i did reset it and unit fired up and ran. i did observe flame and found no abnormalities, good flame and when fan started did not see any change in flame which would have told me bad heat exchanger. i did look at unit next to it and found flame same way. this unit has 2 roll out switches, one on each end, unit is laying horizontal left. should i have ordered new roll out or should i be fine?

[hands]

Did you check the manifold gas pressure and the inlet gas pressure to make sure they were okay? Just yesterday I was checking a Lennox Unit Heater, the customer said it had flames shooting out of the back of the unit. I found several problems that may relate to your Roll-Out fault. The burner crossover passages were clogged with dirt, the gas valve (which is a step valve) was opening fully at times during light-off and the pressure regulator was letting the gas pressure build up to 3 lbs. at times at the inlet of the gas valve, when the burner was off. During ignition, the gas pressure was too high for the igniter to light it and the gas would build up in the heat exchanger. Sometimes it would light right before the gas valve would close and the gas would explode causing the flame to shoot out of the back of the unit. This could be happening to your unit and opening the Roll-Out switch. But it might not happen every time.

[Airmechanical]

Originally Posted by hands

Did you check the manifold gas pressure and the inlet gas pressure to make sure they were okay? Just yesterday I was checking a Lennox Unit Heater, the customer said it had flames shooting out of the back of the unit. I found several problems that may relate to your Roll-Out fault. The burner crossover passages were clogged with dirt, the gas valve (which is a step valve) was opening fully at times during light-off and the pressure regulator was letting the gas pressure build up to 3 lbs. at times at the inlet of the gas valve, when the burner was off. During ignition, the gas pressure was too high for the igniter to light it and the gas would build up in the heat exchanger. Sometimes it would light right before the gas valve would close and the gas would explode causing the flame to shoot out of the back of the unit. This could be happening to your unit and opening the Roll-Out switch. But it might not happen every time.

what he said above, plus i like to feel the temp
around the rollout switch, if it seems real hot
the rollout was doing its job, you need to find out
why its so hot in that area, most of the time
there is a reason that the rollout tripped, if you
cant find a reason,replace the rollout switch.



.

[mdharris68]

Originally Posted by Airmechanical

what he said above, plus i like to feel the temp
around the rollout switch, if it seems real hot
the rollout was doing its job, you need to find out
why its so hot in that area, most of the time
there is a reason that the rollout tripped, if you
cant find a reason,replace the rollout switch.



.

What they said plus i once had a hard time finding the reason for a tripped rollout. 80% horizontal, spark to pilot, endshot burners, natural gas. regulator set correctly at 3.5" w.c., inducer fan pulling low to normal amperage, pilot cleaned. rollout would trip after a long runtime in real cold weather. found out the the original installer should of had installed a 1 inch larger flue. the thing would run fine in moderate weather with 3 to 5 minute cycles, but when it ran for extended periods, the heat inside the burner box would build up and trip the rollout. increasing the flue size made the difference in this case. One thing to look for is a long run time of 15 to 30 minutes if its good and cold, because a heat exchanger may be opening up blowing flame back into burner box. Also, are there any obstructions in the flue? Inducer pulling correct amps? ? be interested to find out what you find. my2cents

[frostedfingers101]

thanks guys for reply,

i did not check inlet and outlet of gas pressure due to when it lit, all appeared normal, it was being pulled in and looked good. it was a horizontal left unit and with both ros on each end of tube, it was the one on the top which was out it did run for 30 mins or so and satisfied and relit when raised the temp to check again, thanks guy guess i will check more if we get a call,i do appriciate it