Furnace not igniting

We just returned from our last trip of the season, and although the furnace worked fine our first night out, it wouldn't light after that (the blower would come on, and you could hear the piezo clicking away trying to light it to no avail). So I don't think the problem is with spiders or other debris blocking jets, although it could be.

We were heading down to Texas where it's a little warmer, and we had a small ceramic heater, so between that and the AC heater, we talked it over with The Car Show and decided to just drop the TM off on our way home. We were able to keep the interior around 60F, even with nights around 30F, between the 2 electric heaters. The Car Show thinks it's the igniter board, which should be covered under warranty.

I'll post a follow-up when they debug it.

[Bill]

Interesting. If you can hear the electronic sparker clicking, trying to light the gas, then the electronic ignition system is not at fault. It is doing it's job. It really sounds like the gas flow is interrupted, so that even though the spark is there, there is nothing to light. Could be spiders or debris in the jets. Does the flame come on at all, even for a few seconds? Once the flame is ignited, there is a flame sensor (basically a heat sensor) that confirms the flame presence, and keeps the gas on. This sensor is located on the igniter board, so if the flame comes on and then goes out, then the flame sensor portion of the igniter board could be at fault.

Let us know what they find. The knowledge will be valuable in the future when the problem comes up again on the board.

Bill

Originally they told me that the furnace lit for them without problems, so it sounded like it was going to be one of those intermittent problems that are almost impossible to debug.

I'm heading down to the Car Show to pick the TM up this weekend, so I gave them a call to see if it's ready. The short answer is that the screws holding the heater body to the floor had become loose in this year's 10000 miles of travel and slight shifts of the heater body could slightly disconnect the ground wire. They debugged this when one of the technicians had a hand on the frame when the thermostat tried to fire up the furnace and received a pretty good shock. With the ground side of the sparking element disconnected, the piezo's 40K or so volts tried to discharge any way it could, and so it was hopping over to the heater frame (and through the tech's arm in this case). So the spark was there, but it was in the wrong place (not over the pilot gas outlet).

So it doesn't sound like it was a gas supply problem after all. Hopefully Monument will stay snow-free Saturday as I drag the TM back home - noaa.com has Saturday's weather as good as any day up there.