The repair-or-replace question comes up every time an HVAC system has a significant failure. There is no single right answer — it depends on the age of the system, the cost of the repair, the system's overall condition, and your plans for the property. Here is a framework for thinking through it.

The 50% rule

A commonly cited guideline: if the repair cost exceeds 50% of the replacement cost, replacement is usually the better financial decision. This is a useful starting point, but it is not a hard rule. A $600 repair on a 10-year-old system in otherwise good condition is probably worth doing. A $600 repair on a 20-year-old system with a history of problems may not be.

Age and remaining service life

Most residential furnaces and air conditioners have a service life of 15–20 years with proper maintenance. A system approaching or past that range is a candidate for replacement even if the current repair is relatively minor — because the next failure is likely not far behind. A system in the 8–12 year range with a single significant failure may still have many good years left.

Efficiency and operating costs

Older systems are typically less efficient than current equipment. A furnace installed in 2005 may have an AFUE of 80% or less. A new high-efficiency furnace runs at 96% AFUE. The difference in operating costs over 10–15 years can be substantial — and that savings should be factored into the replacement decision alongside the upfront cost.

Getting an honest assessment

The best way to make this decision is to have a technician you trust assess the system and give you a clear picture of its condition, the cost of the repair, and what a replacement would involve. A contractor who only recommends replacement — or who only recommends repair — without explaining the reasoning is not giving you the full picture.

Heirloom Mechanical will give you an honest assessment of your system and help you make the decision that makes sense for your home and budget. Call 412-889-6800 or request service online.