Ownership Decision
Repair it, or replace it?
The repair quote is the least useful number in this decision. What settles it is how old the unit is, which part failed, whether that part is still made, and what the repair costs as a fraction of a new install — in that order.
Start with the ratio, not the quote
A repair is worth doing when it buys years that cost less per year than replacing would. That means the only meaningful way to read a repair quote is against what a new unit costs installed — around $12,000 for a 22kW whole-home install in this region, plus a permit. A $900 repair on a six-year-old generator is cheap. The same $900 on an eighteen-year-old unit whose controller is next in line is not.
How much that matters depends on what the outages here actually look like, which the dated record sets out with customers affected and restoration times.
A rough working line: once a repair approaches half the cost of replacing, the repair has to buy several more years to be worth it, and on an old unit nobody can honestly promise that. Below a quarter, on a unit under ten, it almost always is. Between the two, the answer comes from the next two sections rather than from the arithmetic.
What broke matters more than what it costs
Three classes of failure, and they point in different directions regardless of the number on the quote. Nothing here is a diagnosis of your unit — it is how to read the diagnosis you were given.
Wear items — almost always repair
Repair- Battery
- Spark plugs
- Oil and filters
- Air filter
- Belts and hoses
- Fuel solenoid
These are consumables on a schedule, not failures. A unit that will not start on a dead battery is not a unit at the end of its life — it is a unit that missed a service. Replacing one of these on an otherwise healthy generator is never the wrong call.
Serviceable major parts — depends on age
Depends- Automatic transfer switch
- Controller board
- Stator or rotor
- Starter motor
- Voltage regulator
- Enclosure corrosion
Any of these can be replaced, and on a unit under about ten years old that is usually the right answer. On an older unit the calculation changes, because you are putting a new part into a machine whose other parts are the same age as the one that just failed.
Engine failure — usually replace
Replace- Seized engine
- Thrown rod
- Cracked block
- Blown head gasket on an air-cooled unit
- Widespread internal corrosion
An engine rebuild on an air-cooled residential standby rarely makes economic sense, because the engine is most of what you bought. This is the one class where a replacement quote is usually the honest answer rather than the upsell.
Which way the evidence points
Repair is probably right if
- Under about ten years old, serviced on schedule, and this is the first real failure.
- The failed part is a wear item, or a single component with parts still in production.
- It has been carrying the house correctly during outages up to now.
- It is correctly sized for the loads you want covered.
- You are inside the original warranty, or a dealer service plan covers the part.
Replace is probably right if
- The unit is past 15 years old and the failed part is not a wear item.
- The manufacturer no longer supplies the controller or the alternator for that model.
- It has failed to transfer during more than one outage — a generator that does not carry the house during a storm has not done the one job it was bought for.
- The repair quote is more than about half what a new install would cost.
- It was undersized from the start, so a repair returns you to a generator that never covered the loads you actually care about.
- The enclosure or base has corroded through, which in this region usually means it sat where snow and road salt collected.
The parts question decides more than people expect
A standby generator is only repairable while somebody still makes the part. Controllers and alternators are the two that go out of production first, and once they do, a unit that is mechanically fine becomes unrepairable at the first electrical failure. That is why the question is not only “can this be fixed” but “is this still supported”.
Ask before you authorise anything: is the part still manufactured for this model, is it in stock, and what is the lead time. A repair that leaves you without a generator for six weeks in the wrong six weeks is a different proposition from one done on Thursday.
If you replace, what carries over
A replacement is not a fresh install. Some of what you paid for the first time is still in the ground, and that is the part of a replacement quote worth checking line by line — an installer who prices a replacement as though nothing exists yet is quoting a different job.
| Existing work | Carries over? | What decides it |
|---|---|---|
| Concrete pad | Usually | If the new unit has the same footprint or smaller. A larger unit may need a new pad. |
| Gas line | Sometimes | A larger generator needs more gas. An upsize can mean a new run or a meter upgrade, which is a real cost. |
| Transfer switch | Sometimes | If it is sound and correctly rated for the new unit. A failed switch is often what prompted the replacement in the first place. |
| Electrical feed | Usually | Unless the new unit is a step up in output, or the panel was marginal already. |
| Permit | No | A replacement is new work. Municipalities in this region permit and inspect it as such. |
Sizing is the one thing worth revisiting rather than carrying over. If the old unit never covered what you wanted covered, replacing like for like repeats the mistake — the sizing guide works out what the house actually needs, and the transfer switch is what decides which circuits get it.
What to ask before you authorise anything
Ask these of whoever diagnosed it. The answers turn “you need a new one” into something a second company can be asked to price against.
- 01Which specific part failed, and did it fail on its own or take something else with it?
- 02Is that part still manufactured for this model, and what is the lead time?
- 03How old is the unit, from the data plate rather than from memory?
- 04What are the total run hours, and what does the controller log show?
- 05What else on this machine is the same age as the part that just failed?
- 06If I repair it, what is the realistic expectation before the next failure?
- 07What is the repair quoted at, in writing, including labour and the callout?
- 08If I replace it, does the existing transfer switch, pad and gas line carry over?
If a replacement is quoted, the same rules apply as to any install: compare the quotes by what each one includes, and check the licence of whoever is doing the work.
What this page does not tell you
It states no repair price, because repair cost depends entirely on which part failed, and a figure written without knowing that would be a guess dressed as guidance. It does not diagnose your generator, and nothing here establishes that a diagnosis you were given is wrong. The age and ratio thresholds above are decision aids, not rules — a well-maintained unit can outlive them and a neglected one will not reach them.
Get a replacement quote to weigh it against
The repair number only means something next to a replacement number. Tell us the unit’s age and what failed, and we will get you quotes from installers in your part of the region — so the decision is made against two real figures rather than one.
Replacing in your town
Permit fees and inspection requirements are set by the municipality, and a replacement needs both. The permit guide covers what each one asks for.
Generator installers by town
Permit fees, inspection steps and the utility you deal with change from one suburb to the next. These pages carry the local details.