The heat exchanger has cracked on my 14-year-old natural gas furnace. (bummer, but it was a cheap contractor grade unit) Today the “furnace salesman” came to visit and included some things in his bid that seem pretty expensive for what I’m getting. Two things stood out like a sore thumb. The first is a charge of $430 to replace the “B vent” I’ve never heard of a “B” vent before and he said that the vent from the furnace to the stack has to be replaced per national code. The vent in question is at most 3 feet long and is visually in perfect condition. He said that a new double walled vent had to be installed. The furnace is in a dedicated upstairs furnace room with outside combustion air. So if the old vent has to be replaced due to code changes fine, but is $430 out of line? The second charge is $300 for a new pigtail from the hard gas line to the furnace. He said that replacing that was a Utah code. The connection is one of those flexible lines that won’t break if there is an earthquake and the furnace tips over. (Like that could even happen ) Again if its code OK but $300 to install a $25 flex line seems a bit excessive. The total bid was $2,900 for a Carrier 585STA070 (70 K BTU) Labor was $950 The other bid I have is $3,400 for a Trane G50 but there was no breakdown on the individual parts price. TIA Here are the answers to the pertinent questions from the forum stickies. 1. In which area you live and ambient temperatures you usually experience. Utah SLC Area - winter temps go to 0 on really cold nights 2. House style and construction details. Two story with 2x6 exterior walls stuffed with the best insulation R value available. I don't remember the R value number but its as good as I could get when the house was built in 1993. Total square footage is 2500. This furnace heats the 1000 square foot upstairs 3. Make, model and age of equipment related to the problem. The upstairs furnace has failed. It is a 70K output unit topped with a 2 ton A/C unit. We were happy with its performance. 4. Fuel type. Natural Gas 5. Water temperature and pressures of boiler systems. N/A 6. What type of zoning do you have with your boiler system. N/A 7. Thermostat type. Electronic Automatic Set Back 8. Anything else that would be useful. No detail is to small. The furnace is an updraft model. All of the bedrooms are upstairs and the heat is only run in the mornings to make things comfortable for getting ready for work. My estimate is that 30% of the gas is used by the upstairs furnace. (that's probably a bit high) Based on my calculations using the gas bills from last year going from an 80% to a 95% efficient furnace will save $50/year. I am a very advanced DIY'er and while I'm not going to do it myself, the thought did cross my mind.

I see many, many people on the internet say that a homeowner should not install a furnace themselves. But if you search about installing a water heater, everything is OK. Why is everyone in an uproar about installing a furnace? The same principles apply regarding gas hookups and ventilation (assuming both are gas units). So what's the big deal here? Yes, it gets more complicated when we are talking about the duct work on a furnace, but duct work isn't a life threatening issue. It's the gas/vent issue most people seem to be concerned about.