[AJM84]

We have a 1988 mobile home, so I'm assuming the furnace is an '88 model. If memory serves it's around 65000 or 70000 BTU. We've lived there since 2009 so I have no idea how the furnace behaved before then. Of course the previous owner claimed everything was in perfect shape, but who knows?

Nov 2009 - April 2011 The pilot would go out when there were strong winds (40mph or so). We thought the wind was coming down some kind of vent pipe and blowing it out, because to someone who doesn't know about HVAC that seems reasonable. Around Feb 2011 it wouldn't stay lit at all so we bought a new thermocouple and a new digital wall thermostat and that seemed to solve the problem.

Oct - Dec 2011 The pilot started going out again but only with strong winds. Once re-lit everything was fine.

Jan 2012 It wouldn't stay lit for more than a few minutes, not even long enough to complete a cycle. We called a repairman who cleaned everything, installed another thermocouple, a new gas line (the old one wasn't broken just outdated and not up to code), and a new gas valve. It worked great for about 12 hours before the pilot went out again.

The repairman came back, looked at it again, said the heat exchanger must be cracked and they are so hard to find and so expensive that it's best just to buy a new furnace. He also says we're lucky because cracked heat exchangers create hazardous amounts of carbon monoxide. So he charges us nearly $400 for the work he'd done and offers $2500 for a new furnace installed.

We called a friend whose day job is HVAC for a second opinion. He ensured the vents were not blocked, looked everything over, said he was pretty sure the heat exchanger was fine and that if they go bad they make a lot of fumes and it's noticeable. He adjusted the gas flow and that seemed to do it. It worked perfectly for almost two months. Also at this point, the burner flame turned blue instead of the yellow it had been.

Today it's broken again. According to two certified repairmen, if the heat exchanger is cracked or bad it will cause carbon monoxide and/or fumes. We bought a carbon monoxide detector, the levels have never been bad in the house since we've had it these last two months. There are no fumes either.

I googled furnace diagrams and there don't seem to be many parts (besides the blower related ones) left that we haven't had replaced or at least ruled out. Also, our friend says that the wind couldn't be blowing the pilot out because of the way the chimneys are designed, apparently there are two pipes and they're made so that air gets out but not in. But it's an awfully big coincidence that for two years the pilot went out every time the wind blew very hard and no other times.

Could there be a problem with the chimneys? Again, I know relatively nothing about this, but common sense says fire can't burn without oxygen. Maybe there is too little or too much air coming through? Or could some underlying problem be ruining the thermocouples that we keep putting on? Could something be clogging the main gas line only at certain times? I don't think anyone has checked that, only the ones directly at the furnace itself.

If I need a new furnace, so be it. I just want the peace of mind in understanding why mine is beyond repair to begin with. And I don't get why so many things have fixed it temporarily, you would think it either definitely fixes it or it definitely doesn't.

[T-Top]

For 22 years of service not bad. Check for air deprivation. Rust can settle down on top of the choke ring right at the flue pipe connection on the furnace, blocking exhaust. You may have a restriction of fresh air going to the heat exchanger. Your flue pipe passes through the center of the fresh air pipe, if its rusted out your not going to get fresh air for the burner to burn.