12V Furnace Gotcha January 12, 2021, 11:08:55 am I went out to the rig this morning and noticed that exhaust was coming out of the wall furnace vent on the outside. I didn’t leave the propane on overnight so when I went inside I found that the thermostat was all the way down but not off. So, apparently when the inside reached a certain temperature last night, it kicked on with the fan only. The interesting thing is that the air coming out of the furnace vents inside was somewhat warm. I turned the thermostat switch to the off position and waited but the fan didn’t want to stop so I ended up pulling the 12V fuse in the converter box. I then turned on the propane and am now testing the furnace to make sure everything is functioning correctly. These are the types of mistakes that you remember and hopefully won’t make again!
Re: 12V Furnace Gotcha Reply #1 – January 12, 2021, 11:12:52 am Once my furnace reaches the desired temp and kicks off, it shuts the propane off, but lets the fan run.Sometimes it takes two minutes or more for the fan to stop.Maybe try waiting a bit longer to see if the fan stops. 2 Likes
Re: 12V Furnace Gotcha Reply #2 – January 12, 2021, 11:41:40 am Greg, per Jota's experience, it's normal for the furnace fan to run for a couple minutes after the thermostat is "clicked off".
Re: 12V Furnace Gotcha Reply #3 – January 12, 2021, 11:43:07 am Yes, I did wait several minutes but perhaps not long enough.
Re: 12V Furnace Gotcha Reply #4 – January 12, 2021, 01:15:32 pm Hi Greg; I've mentioned this before, years ago, as a 'phantom' current drain. If not off, the thermostat calls for heat, the fan turns on to prove air flow, (sail switch), then tries to light the pilot. If you turned off propane at the tank, it might light with residual propane in the lines, or not. Either way the fan will continue to run until the rig is warm enough inside to satisfy the thermostat. If it is cold enough, that could be days (or weeks). If you have warm enough days, you might not know what is happening nightly. There isn't anything wrong with the heater, just the operator not having the thermosat switch really off. RonB 2 Likes
Re: 12V Furnace Gotcha Reply #5 – January 12, 2021, 01:28:31 pm Concur Ron, operator error for sure. Another one of my “rookie mistakes“. Sometimes we do more harm than good!
Re: 12V Furnace Gotcha Reply #6 – January 12, 2021, 05:58:50 pm Greg, one thing to keep in mind, your furnace is new enough and might not be this way but on the older furnaces if you had the propane off and the furnace tried to ignite and didn't prove flame it would retry about 3 times then lock out. When it locked out, the fan motor would continue to run until the battery was dead or it was turned off on a control switch. Newer furnaces I think would turn the fan off after it locked out. I'm not totally sure on that one. Our old Tioga was famous for locking out when you didn't want it to. Lots of times the battery would get low and the fan wouldn't run fast enough to make the sail switch.Jon 1 Likes
Topic: 12V Furnace Gotcha (Read 222 times)
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Topic: 12V Furnace Gotcha (Read 222 times)
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