Blog · June 27, 2026 · Ray Delgado
Repair or replace? The furnace math that actually matters
Age, the cost of the repair, and how long you are staying in the house — three numbers that answer the question better than any rule of thumb.
The honest version of this decision has three inputs, and only one of them is the repair quote.
1. How old is it?
A gas furnace in this climate runs 15 to 20 years. Under 12, parts are still available and the rest of the machine has life left. Past 18, you are repairing a system that will ask again next winter.
2. What does the repair cost against a new system?
Our working line is a third. If the repair is more than about a third of what a replacement costs, and the unit is past its first decade, the repair stops being the cheaper option in any timeframe longer than a season.
3. How long are you staying?
Selling in two years? Repair, unless it is a safety issue. Staying ten? The efficiency difference between an old 80% furnace and a new 96% one is real money every January.
A cracked heat exchanger ends the discussion
That is a carbon monoxide path into your house. We red-tag it and shut it down — no repair, no exceptions, whatever the age.
Before you decide
Should I replace the AC at the same time?
If the AC is within a couple of years of the furnace's age, doing both at once saves a second labor charge and lets the system be matched. If the AC is much newer, no.
Are the high-efficiency models worth it here?
In Wichita, yes for a house you are staying in — our winters are long enough that the difference shows up on the bill.