Originally Posted by oldbeek
Sfv-42 and yes the high temp switch does open at 410f inside temp of the fire box. Not in the ducts. We had my heater out on a test bench at the NASA lab. Suburban didn't know about the cycling circuit in the board. They didn't know what the snap temp was to be on the high limit switch. We bought 2 of them and they both snapped at 410 degree inside temp of their box. They didn't know what the RPM of the motor is either. We contacted the mfg. of the motor. Speed is 3500rpm. We tested every component individually and watched it run through its cycles on the bench. Cant beat the team at NASA lab.of coarse had a manometer on the propane pressure. 10.5 inch of water. High limit switches may be 130 to 190 as it is fastened to the outside of the fire box.
CORRECT parts are serial nmber dependent.
2 1/2" motor.....400 CFM
3" mtor............430 CFM
Number 49 orifice
Number 50 orifice
195*F High Temp Limit Switch (heat exchanger metal temp)
3 different gas valve assemblies
If wrong parts were installed during repairs..furnace is NOT going to fire correctly