Ayuh,... It's rarely worth it to change a heat exchanger,...have to buy from the mfg. but once you see what it tales you may want to buy a new furnace instead.
too many diff kinds of HXs to be able to give a step by step.:thumbsup:
as mentioned its not a diy project...this has to be ordered from mfg... in most cases has to be a licensed contractor to recieve this part...and yes it is a major job......like a heart transplant.......consider new furnace...ben srim not doing the repair. Just want to know what it takes to do it. So anyone know where to get the HX from?