I am the proud (?) owner of two Consolidated Industries furnaces, which were not a subject of the safety recall, but are known to have a lot of problems with heat exchanger cracking. (For those of you who don't know, Consolidated produced a lot of furnaces under several names before they went bankrupt). Since the water-pressure test for the heat exchangers is about $150 (per furnace) and the CO sniffer test is not 100% accurate, I was thinking about replacement of both units. Plus, my existing furnace is about 70% eficient.

I am a very handy guy and have done most everything there is to do in building a house, but I have never replaced or installed a furnace. How tough is this? It's a gas, heat-only system.

How do you get the things in the attic/crawl space?

I live in San Diego, and thus, although the house is large and poorly insulated, the 75,000 BTu units never run more than about 10 minutes at a time, even on the coldest days. I am assuming that this means they are sized about right.

The existing furnaces are set on a 4 x 4 (the crawlspace) and OSB board (the attic). Wouldn't it be a good idea to set the one in the attic on cement board?

Will I save money doing the install myself? I know I will need a building permit. I promise to check the gas connections with soapy water and hook up the vent properly.

Thanks!