Please see the attached picture and pay attention to the "temperature dial" in the inset
With the current settings the gas burner cycles like this
-limit temperature 200F
-at that temperature the burner shuts off and the furnace is cooling off to around 150F in about 35 seconds
From there the burner starts again and it the temperature goes up in about 1min
The temperatures in the circled area are the highest in the area but stable. I am not sure how hot these should normally be. I just fixed a problem with the control module and in the process I think I played too much with the fan/load control switch. I am trying to guess if everything is back to normal
Best Answer
If you're tripping the high limit, then I'd say it's not back to normal. Sounds like you're not pushing enough cool air through the heat exchanger, which means it can't dissipate the heat fast enough.
With a conventional gas furnace, you should be at about 140°F-170°F at the supply plenum. A high efficiency furnace will be lower, around 110°F-140°F. However, the temperature at the outlet of the furnace, is dependent on the temperature of the incoming air. If you have the documentation for the furnace, it should give you an idea of the temperature rise you should expect.
The expected temperature rise, as well as the max outlet temperature, might also be listed on the nameplate of the furnace.