The reset button on my boiler keeps tripping, and I can't figure out why. The flame is bright, and the CAD cell has no soot on it, so there is no reason why it shouldn't see the flame. I've called out the plumber to look at it and he said everything looked OK. The worst part is there seems to be no rhyme or reason why it's resetting. It will work fine for a day or so, and then trip, often in the middle of the night so we wake up to a cold house. Other times it will trip several times durring the day. (It actually tripped while we were away on vacation in December and we returned to a frozen house with pipes broken in 32 places. We won't be asking those friends to watch our house again!) It seems to trip after it's been running for a while, not when the burner first kicks in. I thought maybe it was running too long and getting the temperature too close to the safety switch temperature (attached to the outflow pipe) but the high cutoff is set at least 10 degrees below what the safety switch is set at. The controller is a Honeywell R8182D. Any thoughts on what else I could check to see why it keeps doing this?

This is a Duomatic Olsen (1988) 117,000BTU forced hot air. Last month we had the burner tech. come. He checked the fuel system and it was ok (said it was a bit dirty. We had just had it serviced last November, but he put in a new nozzle and filter anyhow) He also: Blew out the oil line Tested motor: Good Tested Ignitor: Good Pump pressure: Good Ohms on Cad Cell: Good He found that the end cone was broken, replaced that. He said that was one possibility for the kicking out. He also tested for efficiency with a CO2 thingy (Like I know what it's called--I'm no mechanic) :) Well, it worked great--for about a week. Then it started kicking out more and more frequently. Now I'm running up and down the cellar steps continually (oops. reminds me--gotta make a cellar run now to press the reset button) It fires up immediately. It's not overheating because sometimes it will just start and kick out after maybe 5 seconds. Sometimes less than that. There seems to be no consistency to how long it will run before kicking out. Husband is thinking now that it could be the control box. Does this sound right ? He's a millwright, and understands these machines way better than I ever will. Any idea on what these control boxes will cost? We're on a tight budget. I hate to call the repair man if it's something we can do ourselves. But I'm also thinking that this thing could just finally refuse to start one of these days. And we're just about out of wood. And Maine still has another couple of months of furnace running season yet.