Every furnace owner hits this fork eventually: the repair quote is in hand, the unit is getting up in years, and you’re wondering if you’re about to throw good money after bad. Here’s the framework we use — and you can use it yourself.
The 50% Rule
Multiply the furnace’s age by the repair cost. If the repair costs more than 50% of what a replacement would — and the unit is past mid-life — replacement usually wins. A $700 blower motor on a 17-year-old furnace is a very different decision than the same motor on a 7-year-old one.
Know the Lifespan
Gas furnaces typically run 15–20 years with maintenance, less without. If yours is in its late teens, every repair is borrowing time — which can still be the right call, but go in with eyes open.
Factor in Efficiency
An older 80% furnace sends 20 cents of every gas dollar up the flue. A 96% AFUE replacement cuts that to 4 cents. Over a Wichita heating season that gap is real money — and high-efficiency units often qualify for federal tax credits and utility rebates that soften the upfront hit.
The Safety Line You Never Cross
A cracked heat exchanger isn’t a math problem — it’s a carbon monoxide risk, and it ends the conversation. If a technician shows you a crack, replacement is the answer. (Also: ask to actually see it. Reputable techs will show you.)
Comfort Counts Too
If some rooms never warm up, the furnace roars like a jet, or it runs constantly without keeping up, a properly sized new system fixes things no repair can — older units were often oversized or undersized from day one.
Our Actual Advice
Get the diagnosis and the repair price in writing, ask for the furnace’s honest remaining-life assessment, and get a replacement quote at the same visit. With both numbers in hand, the right answer is usually obvious.