furnace
When my electric furnace shuts down the fan also shuts down at the exact same time. I was told that it should run for a bit afterward to cool off the coils. Doing some research it looks like this is part of most, if not all furnaces. Is there setting that can be done to troubleshoot/resolve this? Possibly an adjustment somewhere?
Furnace is Central Electric, Model EB23B
I finally found some time yesterday to take a closer look at the furnace.
I started by measuring the incoming gas pressure using a gas pressure gauge. I found it to be 6 WC (inch water column), which is well within the acceptable range specified on the furnace.
Next I took a closer look at the spark gap itself, and watched closely as the spark was generated. I even recorded the spark with my video camera, which allowed me to zoom in fairly close. This is when I noticed a bit of carbon buildup on the electrodes, and wondered if it could be that simple...
I grabbed a bit of 220 grit sandpaper, and cleaned the electrodes up a bit. steel wool is probably the tool of choice for this job, but I didn't happen to have any on hand at the moment (not yet unpacked).
After testing the pilot ignition a few times, the problem seems to be fixed. We had a cold night last night, and the furnace fired up fine all night. As I write this, the furnace has just cycled successfully yet again.
I found this YouTube video from Grayfurnaceman that describes the problem exactly, and says that the only solution is to replace the assembly. I'll be replacing the pilot assembly once the weather warms up, so we'll see if that solves the problem.
This isn't a great answer but I want to provide something in case it helps others.
There was no issue with my flame sensor or the ignition device. It went on just fine but was kicking off due to some other reason.
After a lot of troubleshooting it was fixed by one of three reasons:
powering off the furnace for a couple hours with thermostat disconnected.
installing new thermostat. I was due for a new thermostat and not sure what could have been wrong with the old one. It did run out of batteries right before this but it doesn't make sense that when I left the old thermostat it worked fine with the furnace cover off. The only thing I can think of is the old thermostat was sending incorrect signals to the furnace that caused it to need more air during usage (maybe an AC expert might be able to give a plausible reason for this).
Reseating cover with slight gap. I have since put this fully on but left it with a slight gap the first couple of weeks.
I did nothing else to the unit and the unit was in otherwise pristine condition - only a couple years old.
Best Answer
Gas and oil furnaces heat a heat exchanger so they have to run for quite awhile after the burner shuts off to cool down. Electric furnaces don't have that issue since there is no heat exchanger. If the air is still hot when it shuts off, the sequencer needs checked. If the air is warm, it's normal.