$7,100. That's what it cost to take a working 1998 furnace out of our basement in August, and I've been arguing with that number since the first quote came in during July. This is how we got there, including the $650 piece nobody mentioned until the second estimator walked down our basement stairs.
Why August, while it still ran
The old furnace was a 1998 Carrier, 80 percent efficient, 70,000 BTU, venting up the brick chimney it shared with the water heater. It got a new inducer motor in January 2025 under the home warranty we had that first year, and at last October's $119 tune-up the tech called it old but sound. The energy assessment last September flagged it as aging, which at 27 years seemed generous.
In May we priced a cold-climate heat pump at $15,800 plus a $3,200 panel upgrade and decided on a two-stage gas furnace for now, with the heat pump question coming back when our 2011 AC dies. That left timing. At work, the expensive orders are always the rush orders, and a furnace that quits in January is a rush order: you take whatever is on the truck at whatever price, with a space heater going and one eye on the pipes. I'd rather shop in July.
Three quotes
We got names the way we get them now, from Gary and the neighbors, and all three companies came out on Fridays, my work-from-home day.
- $5,900: a big regional company, a single-stage 96 percent furnace sized at 70,000 BTU to match the old one.
- $6,450: a family-owned company on the south side, a Bryant 96 percent two-stage at 60,000 BTU, with a PVC side-wall vent and a 4-inch media filter cabinet.
- $7,800: a variable-speed 96 percent unit.
The middle quote was the only one with a room-by-room heat-loss calculation, and it counted last October's attic and knee-wall insulation. That's where the 60,000 came from. A two-stage furnace spends most of its time on low fire, which should mean longer, quieter runs and fewer swings upstairs under the sloped ceilings. That was worth $550 more to us than the single-stage. The variable-speed unit was another $1,350 for what looked to me like a smaller step up. That's how we weighed it for our house; an installer who has actually stood in your basement is the one to ask about yours.
The chimney liner
The south side estimator was the first to bring up the chimney. Once the furnace vents out the side wall in plastic pipe, the water heater is left alone in a flue sized for two appliances. A small appliance in a big, cold masonry chimney may not draft well, and its exhaust can condense inside. The fix was a liner sized for the water heater: $650, for a total of $7,100. Neither of the other quotes listed it, so as written they weren't really apples to apples.
Here's where I own something. When the water heater died last November, we replaced it with another model that vents up the chimney. It was the quickest choice on a week with no hot water, and I never thought about where the furnace would vent a year later. A different kind of water heater might have avoided the liner. I don't know that it would have been cheaper overall, because I never asked.
Install days and paying for it
I took Tuesday and Wednesday, August 18 and 19, off work. A crew of two showed up at 7:30. The old furnace went out the side door in pieces, and the new one was set and connected by mid-afternoon. The vent and intake pipes went out through the rim joist, right through the foam board I put up last October, so that evening I sealed around both pipes with canned foam. The condensate line runs to the floor drain. Moose spent Tuesday at Gary's, because the crew brought a shop vac.
Wednesday was the liner, reconnecting the water heater, the gas hookup, startup, and their combustion and draft checks. Before they left I pressed the test button on every carbon monoxide alarm in the house. The installer connected the second-stage wire to our ecobee, and I'll go through the staging settings before it gets cold. The permit and inspection were on them.
We paid $2,600 from the house fund and $4,500 from savings. They offered "0% for 18 months," and the fine print said that if any balance remained after month 18, interest would be charged all the way back to day one. We probably would have paid it off in time. "Probably" was doing too much work in that sentence, so we declined, and we passed on borrowing against the house too. That was our call for our situation.
The $250 Consumers Energy rebate is applied for and we're waiting on the check. As I understand it, the federal credit we used for the insulation doesn't cover work done in 2026, but that's a question for a tax preparer. For now the new furnace sits in the basement, white and quiet, with nothing to do until October. I've gone down to look at it twice anyway.
