I was once afraid of working on my gas furnace, but after doing some simple jobs on my 17 year old Carrier (replacing the transformer, changing the ignitor, updating the vent damper) I have come to the conclusion that they are very much like gas-powered computers with lots of plug-in, plug-out components.
Assuming I keep replacing all the bits that go wrong with new bits until the heat exchanger goes, which I would never attempt to replace, how long will a gas furnace last?
Put another way, what is the life of a heat exchanger and how do I know when it's broke? Or will it last forever?
I am a little worried that the cash I am spending on new parts will outweigh the cost of a new furnace, but I am a long way off that at the moment. I hope to replace my circuit board at the weekend with a more modern replacement, just for the heck of it, and I do not like the old relays.
I am not fiddling with anything connected to the gas and only replace components with the exact part number (or a more modern equivalent). I am very impressed with the number of spare parts that continue to be manufactured so long after the furnace was originally made. I am less impressed with the price they cost.