A standby generator is the most expensive piece of electrical equipment on a typical Ontario property — and the one that gets the least attention. The unit sits in the side yard, runs its 12-minute exercise cycle every week, and the owner assumes it is ready. Most are not. Here is the annual fall service routine we do on Generac, Kohler, and Cummins residential units in September and early October, before the first ice-storm advisory of the year.
The exercise cycle nobody actually checks
The weekly exercise is good for the engine. It is not a test of the system. The exercise runs the generator without load — the transfer switch never transfers, the panel never sees the generator power, the well pump never starts. A unit can pass exercise cycles for two years and still fail the moment a real outage asks it to carry the house.
The annual service is what tests the system end-to-end. If you bought the generator from a dealer who recommended an annual maintenance contract, that is what they were selling — and they were right.
The fall service checklist
- Oil and filter. Air-cooled Generac and Kohler residential units use SAE 5W-30 synthetic in the cold-weather window. The factory-fill at install is rarely changed before the first season. We pull the dipstick, drain the pan, change the filter, refill to spec, and note the hours on the service log.
- Air filter. Inspect, blow out with low-pressure air or replace. Mice love these. We find nest material in air-filter housings constantly on Muskoka cottage units that sit unused for months.
- Spark plug. Every other year on most air-cooled units, annually on harder-worked Cummins liquid-cooled units. Gap to spec.
- Battery. The single biggest failure point on the system. A starter battery loses capacity in cold weather and a 4-year-old battery will not crank a cold-soaked engine at -20°C. We load-test every battery in fall service. Marginal batteries get replaced before storm season, not during it.
- Battery charger. Most standby units have a trickle charger on the battery. Verify the charger is live, the voltage at the battery is in spec (typically 13.2–13.8 V float), and the charger fuse has not opened.
- Coolant (liquid-cooled units only). Cummins residential units and some larger Kohlers use ethylene glycol. Check level and concentration with a refractometer — not a guess.
- Fuel system. Propane regulator condition (the rubber diaphragm gets brittle), gas line for any leaks at fittings (soap test), tank level for owners with a buried tank. Natural-gas units get the meter sized and the inlet pressure verified at no-load and at start.
- Transfer switch. Open the cover, inspect contactors for arc-pitting, torque the line and load lugs to spec, check the controller for fault codes and clear the log.
The test owners skip: the real transfer test
This is the step that makes the difference. With the generator serviced and the transfer switch inspected, we do a real outage simulation:
- Open the utility disconnect at the meter base (or pull the main breaker at the panel) to simulate a real outage.
- The automatic transfer switch should sense loss of utility, signal the generator to start, wait for the engine to stabilize (typically 10–20 seconds), then transfer the load.
- Walk the house and verify the circuits that are supposed to come up on generator are actually live. Well pump cycles, furnace fires, fridge hums, lights come on in the right rooms.
- Restore utility power. The ATS should sense it, wait its retransfer delay (typically 5 minutes), transfer back to utility, and cycle the generator through its cool-down before shutting down.
This is when you find out the transfer switch contactor that has been chattering for six months will not actually pull in under load. It is also when you find out the well-pump circuit was inadvertently left off the generator panel during the original install — a surprisingly common discovery.
Load-bank testing: when it is worth it
A load-bank test runs the generator at progressively higher loads (50%, 75%, 100% of rating) using a resistive bank, with the unit isolated from the house. The point is to verify the unit can actually carry its rated capacity, that the voltage regulator holds frequency under load, and that there is no surprise hidden in the alternator or governor.
For residential 14–22 kW units, a load-bank test every 2–3 years is reasonable insurance. For larger residential units (26 kW and up), commercial standbys, and cottages where the load is well-pump-dominant (heavy inrush, voltage dip), annual load-bank is justified. We bring the bank with us; the test takes about an hour and produces a printed report you keep.
Cottage units: the seasonal-use math is different
A Muskoka cottage generator at a typical Lake of Bays property might run zero hours in a normal year but be the only thing standing between the freezer and a thaw on the one weekend in February when an ice-storm takes the line down. The service interval cannot be "every X hours" because the X is small. Service it annually on calendar regardless. Detail on sizing for cottage loads is in our generator sizing post.
What we leave you with
- Service log entry with hours, parts replaced, fluid changes, controller readings
- Battery test results (cold cranking amps measured vs. rated)
- Transfer test pass/fail on every circuit on the generator panel
- Fault code history from the controller, with any codes explained
- Recommendations for next-cycle work — battery age, contactor condition, fuel-system items
When to call us
If your standby generator has not been serviced in 12 months or more, this is the month to book it. We service Generac, Kohler, and Cummins residential and small-commercial units across Muskoka, Hamilton, Burlington, Waterdown, and Oakville. Request a fall service visit and we will get you on the schedule before the first major storm advisory.