How much does a furnace cost to replace?

Where the money goes

Equipment is typically 45–55% of the total. The rest is labour, venting, electrical, gas connection, permit and inspection, and haul-away. A furnace in a garage closet is straightforward; the same furnace in a cramped attic with a pull-down ladder costs meaningfully more in labour — and that difference is why quotes vary so much between houses that look identical from the street.

80% versus 95% AFUE, and why the answer is different in Texas

AFUE is the share of fuel that becomes heat in your house. A 95% condensing furnace wastes a quarter of what an 80% unit does, which in Minnesota is serious money. In Frisco the heating season is short — a handful of genuinely cold weeks — so the $1,400–$2,400 premium takes considerably longer to return.

Condensing furnaces also need a condensate drain and different venting, PVC rather than metal flue, which adds install cost in homes not already set up for it. For many Frisco homes an 80% furnace is simply the rational choice, and it is worth being suspicious of a contractor who will not quote one.

Sizing, and the usual mistake

Oversized. A furnace with too much capacity short-cycles all winter: fires, satisfies the thermostat, shuts off, repeats. That produces temperature swings you can feel and wear on the ignition components.

There is a second-order problem too. In nearly every home the furnace blower is also the air handler for your air conditioning, so a furnace sized on heating alone can leave you with a blower that is wrong for the cooling load — which means an air conditioner that never delivers its rated airflow.

Signs it is time

• Age past 20 years.
• A cracked heat exchanger — a safety matter rather than a cost one.
• Gas bills rising without a rate change.
• Repeated repairs across consecutive winters.
• Rooms that never even out.

A furnace at 15 years with one failed inexpensive part is usually still worth repairing.

Doing it with the air conditioning

If both are past ten and within about five years of each other, replacing together costs 15–25% less than two separate jobs and gets you a properly matched blower and coil.

What drives the labour half of the bill

Roughly half the cost of a furnace replacement is not the furnace. The variables that move it:

• Location. Garage closet at floor level is the cheap case. Attic, horizontal, with a pull-down ladder and a platform to work from is the expensive one, and can add $600–$1,200 in labour alone.
• Venting. Moving from an 80% to a 95% condensing furnace changes the venting from metal flue to PVC, usually routed to a different termination point. That is real work, and it is the single most common reason a condensing quote comes back higher than the equipment difference suggests.
• Gas line sizing. Occasionally the existing line is undersized for the new input rating, particularly if other gas appliances have been added since.
• Electrical. A new furnace may need a dedicated circuit or a service switch the old one did not have.
• Condensate handling. Condensing furnaces produce acidic condensate that needs a drain and, in some configurations, a pump and neutraliser.

Getting quotes that actually compare

Furnace quotes are unusually hard to compare because contractors describe the same job differently. Ask each one for the same four things and the comparison becomes trivial:

1. The model number and its AFUE rating, not just “a 95% furnace”.
2. The input BTU rating, and what load calculation produced it.
3. Whether venting changes are included or excluded.
4. The labour warranty term, separately from the manufacturer’s parts warranty.

If one quote is dramatically cheaper, it is usually one of three things: a lower-tier model, venting excluded, or no permit. All three are worth knowing about before you choose.

The heat pump comparison

If you are replacing the air conditioner anyway, a heat pump is worth pricing against a furnace-plus-AC pair rather than against the furnace alone. It does both jobs from one piece of outdoor equipment, and it attracts the larger $2,000 federal credit rather than the $600 one. In a house with no gas service that comparison is usually decisive. With gas already connected it is closer, and depends on your electricity rate more than on anything else.

Heating and furnace installation →