Woke up this past Sunday morning to a very cold house (~57 degrees). Taking a trip downstairs and saw the ignition had tripped during the night and cut off the furnace.
After a very hopeful reset of the ignition and waiting it of course tripped again…and the fun begins after a trip to the garage for a few tools.
From past experience I knew that the motor should start up prior to the ignition clicking to fire the furnace. After resetting, the motor was not starting up and the ignition was not clicking to fire it up. I took everything apart are starting inspecting the wires, taking pictures of everything to remember how it went back together.
I scoured the internet for a place that was open on Sundays, and then a place that would potentially have a new motor. The best I could find was from Grainger and wouldn’t be available to get until Tuesday (2 days from when it stopped). Two days without heat didn’t seem very acceptable but after considering calling the guy to fix it I sat on it for an hour and re-grouped.
After circling back, I looked into the ignition controller itself. I realized it appeared to be humming which I had previously thought was the motor. I disconnected the motor from the ignition and still heard the humming which seemed odd. Jumping the motor to 120V to bypass the ignition relay caused the motor to come to life and spin. This meant the motor was OK. I checked the output from the ignitino controller to the motor and didn’t see the voltage increase after turning it on. At this point it seemed very likely that the controller itself was bad. I began looking for replacement ignition controllers and found them on Lowes and Home Depots websites, all local stores did not stock them. Broadening the search out further I located one in the Lowes in Rome, NY.
After a rather boring 2.5 hour round trip I grabbed the part out of the online order mailboxes at Lowe’s and started installing it.
Installation was smooth and I had the new controller ready to test.
Before testing I cleaned the fuel oil nozzles, these get rather dirty and usually require at least 2 cleaning a year. When they are really bad they will block the fuel oil into the furnace and also cause it to trip the breaker. The main difference in the failure mode is the motor will be spinning when this happens, it will also try to click to ignite the fuel but fail and trip the breaker after ~60 seconds.
All cleaned and assembled I was very happy that the furnace started up and we once again had some heat!
The engineer in me wanted to know what was in side this ignition controller so I took it apart in the garage and noticed a bad solder joint that likely caused the failure. Probably could re-solder this and get it working again but…I tossed it.
