When the furnace or AC quits on the worst possible day, it is hard to make a clear-headed money decision. Run these quick tests before you sign anything.
The 50% rule
If a repair costs more than half the price of a new system, replacement usually wins. A common variation multiplies the repair cost by the unit's age — a high number points toward replacing.
Age matters
Most systems last 15 to 20 years. Past the 15-year mark, efficiency has usually fallen and parts get harder to find, so pouring money into repairs has diminishing returns.
Watch the warning signs
- Energy bills creeping up season over season
- Frequent repairs in the last two years
- Uneven temperatures from room to room
- An older system using a phased-out refrigerant
The efficiency upside
A modern high-efficiency system can meaningfully cut your energy use, which softens the sticker shock of replacement over time.
Before you decide
Get a second opinion on any big-ticket diagnosis, ask for the model's efficiency rating, and confirm whether a maintenance plan is included. A well-maintained system simply lasts longer.
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