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Decide repair or replace with four facts: the equipment's age against its expected life, the repair cost against the replacement cost, the history of repairs on that unit, and the consequence of the next failure. Old equipment with an expensive repair and a history of trouble gets replaced; new equipment with a cheap, first-time repair gets fixed. Everything in between is a judgment, and the record of the unit is what makes it a good one.
The decision is easier if the four facts are already written down, which is the practical case for reading the labels and recording the dates long before anything breaks.
What are the four questions?
Ask how old the unit is relative to what it is expected to last, how the repair price compares to a replacement, how many times it has needed repair before, and what happens if it fails again at the worst time. A water heater near the end of the Department of Energy's 10-to-15-year range, needing its second repair, in a finished basement, is a replacement; the same repair on a five-year-old unit in a garage is a repair.
| Question | Points toward repair | Points toward replace |
|---|---|---|
| Age versus expected life | Early in its life | Past the midpoint, or beyond the typical range |
| Repair cost versus replacement | A small fraction of a new unit | A large fraction, or repeated small repairs adding up |
| Repair history | First problem | Second or third problem in a few years |
| Consequence of the next failure | Inconvenience | Water damage, no heat in winter, a safety issue |
| Warranty | Still under manufacturer or builder warranty | Warranty expired |
| Efficiency and parts | Parts available, efficiency fine | Parts scarce, or a new unit would cut operating cost meaningfully |
| Your plans | Selling soon; a buyer may replace anyway | Staying for years |
How does the record change the answer?
The record changes the answer because most of the four facts live in it. The install date and model come from the label you photographed; the repair history comes from the log; the warranty status comes from the dashboard. Without the record, the technician's guess about age and your memory of past repairs stand in for facts, and the decision gets made on the price alone.
When a technician quotes a repair, write the diagnosis, the part, and the price on the unit's page before you decide. If the same unit is back on the schedule within a year, the record has made the next decision for you.
How do the common systems differ?
Each system has its own shape of decision. A water heater tips toward replacement once the tank itself leaks or it passes the DOE's typical life; a furnace or air conditioner is expensive to replace, so a single mid-life repair is usually right until the heat exchanger or compressor fails; a roof is repaired while the problems are local; and appliances are repaired while young and replaced when a repair nears half the cost of new.
- Water heater: any leak from the tank itself means replace; a valve, an element, or a thermocouple means repair. The flush guide and the relief valve test are what extend its life.
- HVAC: repair a mid-life unit; replace when the heat exchanger cracks, the compressor fails out of warranty, the refrigerant type is being phased out, or the repair history has three entries in two years. The annual tune-up is where the technician tells you which way it is heading.
- Roof: repair flashing, boots, and a few shingles; replace when granule loss and curling are general, or leaks appear in more than one place. The yearly inspection tracks the trend.
- Appliances: repair a young unit with a cheap part; replace when the repair nears half the cost of new or the unit is out of parts.
What should you do before anything breaks?
Before anything breaks, record the install date, model, and serial of every major unit, know its warranty status, keep the maintenance that the warranty and the manual expect, and decide in advance what you would do at the next failure of the oldest units. Then when the water heater goes on a Sunday, the answer is already written on its page, and the only call is to the plumber. The maintenance budget is where the replacement money comes from; this post is about deciding when to spend it.
Common questions
Is there a simple rule of thumb?
A common one is that a repair costing more than about half of a replacement, on equipment past the midpoint of its expected life, points toward replacing. Treat it as a way to frame the question, not an answer; a cheap repair on old equipment can still make sense if you are selling next year, and an expensive repair on new equipment can be covered by warranty.
How do I know the expected life of my equipment?
From the manufacturer, the manual, and the install date on the label. The Department of Energy puts storage water heaters at 10 to 15 years; for other equipment, ask the technician what they see for that brand and model and write down the answer. Your own repair record for the unit matters more than any average.
What if the technician pushes for replacement?
Ask for the diagnosis in writing, the repair price, and the replacement price, and ask what they would do if it were their house and why. Then get a second opinion if the replacement is expensive. A good technician can explain the failure mode; a sales pitch cannot.
What should you do next?
Find the oldest major unit in the house and write its four facts on its page today. That is the one most likely to make you decide in a hurry, and it is now the one you have already decided.