How often does a standby generator need maintenance?

A standby generator needs attention on three timescales. Every week it should run a short automatic self-test. In between, an owner can make a few quick visual checks. And at least once a year, a trained technician should service it, with Generac recommending a visit every 6 months. Running hours matter as well as the calendar, so a long outage can bring the next service forward.

Professional service: every 6 to 12 months

Generac is direct about it: "All generators require periodic maintenance, such as oil and filter changes," and "We recommend you have your unit serviced every 6 months by an authorized independent service dealer."^[1] Kohler's owner's manual says: "Have an authorized distributor/dealer service the generator set at the designated intervals in the service schedule for the life of the generator set."^[3] It adds a note that applies to many Virginia homes: "Service units subject to extreme weather, long operating hours, or dusty or dirty conditions more frequently."^[3]

What a service covers depends on the model, so the manual's schedule is the one to follow. As an example, on Kohler's 14 kW home models the schedule says to change the oil yearly or every 100 hours and the oil filter yearly or every 200 hours; on the 20 kW models both are yearly or every 150 hours.^[3] It calls for spark plugs yearly or every 300 hours on the 14 kW models, and air cleaner service at 150 and 300 hours.^[3]

The rest of Kohler's schedule is a good picture of what a thorough visit includes. It says to check the battery charger's operation and charge rate monthly, clean and tighten the battery terminals yearly, inspect flexible fuel lines and connections quarterly and the fuel piping yearly, and tighten control and power wiring connections yearly.^[3] Some items are for the dealer alone: brushes and collector ring yearly or every 300 hours, and a winding insulation test every 3 years, both marked for an authorized dealer only.^[3] Our answer on what a standby generator service visit includes goes through a visit in detail.

The weekly exercise

Between visits, the generator looks after itself with a scheduled run. "Exercising the generator set weekly or every two weeks is required to keep the engine and alternator in good operating condition."^[3] Kohler's default unloaded cycle runs for 20 minutes: 10 minutes at reduced speed to warm up, 3 minutes at full speed while the controller runs its diagnostics, and 5 minutes of cooldown.^[3] During that run it checks the transfer switch connection, battery voltage, engine speed, output voltage and frequency, and oil pressure,^[3] and shows a warning if something is off. On frequency, the manual's advice is short: "Weekly exercises are recommended."^[3]

A loaded exercise also moves the house onto generator power for 20 minutes, which proves the transfer switch works, but power to the building is lost for up to 10 seconds during load transfer.^[3] Ask your installer which mode suits your household.

If you never hear your generator run on its scheduled day, or the controller shows a warning afterwards, call for service before the next storm rather than after.

What an owner can keep an eye on

Some of Kohler's weekly items are simple looks around the unit: checking for exhaust leaks, obstructions or combustible materials near the exhaust outlet, and signs of vibration, leakage, unusual noise or deterioration,^[3] plus the main tank supply level^[3] on a propane unit. Keeping the area clear matters. Kohler's installation rule is: "No plants, shrubs, or other combustible materials are allowed within 1.2 m (4 ft.) of the exhaust end of the generator set."^[4] Leaves, mulch, snow drifts and overgrown shrubs are the usual offenders.

Watch the controller too. Kohler's Next Maintenance screen shows the hours of operation until maintenance is due and an estimated date.^[3] Generac's Mobile Link app shows operating status and the maintenance schedule^[1] for a connected unit. Keep the paperwork: "Maintain a record of repairs and adjustments performed on the equipment."^[3] It helps the next technician.

Leave the enclosure closed. A standby generator can start on its own at any time, and Kohler warns: "Accidental starting can cause severe injury or death."^[3] Engine, battery, fuel and wiring work belongs to the technician.

During and after a long outage

Running hours count. Kohler's schedule includes checking the oil level every 8 hours of running,^[3] so a generator that runs for days through an ice storm needs attention while it works, and an oil change may come due long before the yearly visit. Agree in advance with your service company how they handle oil checks during long outages, and book a service once the power is back. Our answer on why a standby generator might not start in an outage covers what tends to go wrong when maintenance slips.

Because any engine makes carbon monoxide, Ready.gov's advice applies whenever a generator runs near the house: "Install working carbon monoxide detectors on every level of your home."^[5]

When to call a licensed pro

Book a service on your manufacturer's schedule, at least yearly and more often if outages are frequent or the unit sits in a dusty or exposed spot. Call sooner for any controller warning, a missed weekly exercise, a battery or charger alert, a smell of gas, or after a long run. Many owners use the maker's dealer network; Generac takes service requests online by serial number and passes them to a local certified service provider.^[2]

Regulated work on the system needs a licence. Virginia defines an electrician as a tradesman who performs the construction, repair, maintenance, alteration, or removal of electrical systems regulated under the Uniform Statewide Building Code,^[6] and Virginia law requires a licence to work as a tradesman, as a liquefied petroleum gas fitter or as a natural gas fitter provider.^[7] Check the licence of anyone you hire, and see what generator service costs in Virginia.

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