How Long Can You Run a Whole House Generator?

The runtime of a whole house generator depends on several factors including the fuel type, fuel capacity, and the load it is powering. This article explores these factors in detail to help you make an informed decision and maximize the efficiency of your generator.

Fuel Type

The choice of fuel can significantly impact how long your whole house generator can run. Here are the typical runtimes for different types of fuel:

Gasoline: Typically, gasoline generators can run for about 8-12 hours on a full tank, depending on the load. Propane: Propane generators can run for about 8-20 hours on a full tank, again depending on the load. Natural Gas: Natural gas generators can run indefinitely as long as they have a continuous supply of gas. This makes them ideal for long-term power needs but requires a stable source of natural gas.

Fuel Capacity

The size of the fuel tank plays a critical role in extending the runtime of your generator. Larger tanks allow for longer operation times before needing a refill. This is especially important if you are dealing with extended power outages.

Load

The total wattage of the appliances and systems being powered will also impact the runtime of your generator. Running fewer high-wattage devices can extend the runtime significantly. Proper load management is crucial to ensure efficient and safe operation of your generator.

Generator Size

The size of the generator, measured in kilowatts (kW), influences its efficiency and fuel consumption rates. A typical home standby generator around 20 kW might run for 24 hours or more on a large propane tank, provided the load is managed properly. It is always best to consult the manufacturer's specifications for your specific generator model.

For example, a 22 kW Generac backup generator that runs on propane costs about $3.00 per hour to operate. It is essential to note that this generator is not rated for continuous operation as a sole power source. It is intended for backup purposes only.

Generator Duty Cycle

The duty cycle rating of the generator also determines how long it can run without needing maintenance. Many diesel generators can be run until service is required, as they can handle continuous operation for longer periods than gasoline or propane generators. In contrast, gasoline or propane generators may require frequent refueling and maintenance.

Generator Maintenance

To ensure your generator can operate for as long as possible, regular maintenance is crucial. Here are some key considerations:

Engine Oil Changes: For small petrol engines, oil changes are typically every 10 to 20 hours. Small diesel engines may require oil changes every 200–300 hours, while natural gas engines can go up to 2000 hours between oil changes. Extended Oil Sump Arrangements: If cost is not an issue, you can run extended oil sump arrangements and even dual switchable sumps to extend the time between oil changes. Mechanical Maintenance: After the initial run time, which varies based on the type of generator, you will need more significant mechanical maintenance every 5000 to 12000 hours.

Proper setup can sustain continuous operation for a week or more, with relatively short stops for regular maintenance, allowing your generator to operate for years. However, always consult the manufacturer's guidelines for the best practices and care instructions specific to your generator model.