Furnace Woes

[wookster]

First off, happy holidays everyone, I hope they were good to you.

Second, I'm having furnace issues. My house has two furnaces and the one for the upstairs won't kick in by itself. The fan runs/works just fine, and if I go down and turn off the main power to it and back on it will ignite but once it goes off it won't ignite again. Furnace is about 17 years old.

Maybe Everlast is lurking in the forums and can shed some light?

[transplant99]

I went through this exact thing a couple years ago...just worked it as long as i could before it stopped alltogether (4-6 weeks maybe but running to the basement everytime became a pain). IIRC it was something to do with the control board, but was no longer economically viable to repair or parts were no longer available, so we had to replace it....which turned out ok because of how highly efficient and truly just better the new one is.

[wookster]

Well...I hope a new furnace isn't whats needed, but its running now for the moment...wierd.

[wwkayaker]

I had a problem with my furnace the other day that sounds similar. The repair tech said the ignition electrode was covered in combustion material. He cleaned it up and checked the voltage. The furnace is working properly now.

[Titan]

Not a furnace guy but what kayaker said is likely the cause.

Happened to mine several times. I took off the door and then found the electrode that sits in the flame of one of the tubes. Took it off and sanded it with sandpaper and good as new. Also, be sure the switch that the furnace door depresses is being pushed down when you replace the doors.

[Radio]

I had the same thing and it was the Ignition Sensor. I didn't know about the cleaning thing and mine had quit completely so I had to have it replaced on an emergency call. It was pricey because of that, so the sooner you get to it the better.

[wookster]

thanks guys, will check that out.

[DeluxeMoustache]

Some furnaces have a LED, mine is in the blower area, visible through a sight/ window, that flashes when the furnace trips. I have a Carrier furnace.

It was flashing three short, one long. That means code 31. On the inside of the furnace door was a chart with the furnace codes. This was related to a pressure switch.

The general recommendations were looking for reasons for low air flow - insufficient combustion air , blocked vent, etc.

In my case, the root cause was that there is a condensate trap that was clogged and full, backing up condensate in to the heat exchanger. Apparently this is common as well with some Carrier furnaces

Edit - thanks to Everlast. He was out of town when I emailed, but was very responsive and put me in contact with a tech who was in town, and came to get my problems resolved.

[wwkayaker]

The tech who came out to my place said to use steel wool rather than sandpaper if you clean the sensor/electrode. The reason is due to surface area changes caused by the sandpaper which change the voltage.