Guardian Blog: Home Generator Resources

How Whole-Home Backup Generators Work

Written by Brad Nash | Oct 2, 2025 3:15:00 AM

Power outages can disrupt daily life, but a whole-home backup generator ensures your home remains powered. Here's how these systems operate:

1. Fully Automatic, Always Sensing Power

Today, your home relies on a single power source, utility power from the street connected directly to your breaker panel.  Guardian Home Generators will install an Automatic Transfer Switch (ATS) between your breaker panel and the utility power.  

The ATS connects both your generator and the utility power to your home’s breaker panel.  The ATS continuously monitors the utility power.  When an outage occurs, it detects the loss and then automatically restores power to your home using the generator within seconds.  While your generator is running, the ATS continues to monitor utility power. Once utility power is restored, the ATS seamlessly switches your home back to the utility and places the generator back into standby mode, ready for the next outage. That's it, fully automatic start to finish.

2. Power Generation

A whole-home standby generator uses a combustible engine to drive a power-generating alternator. Most homes are well served by an 18 kW to 28 kW air-cooled generator. Larger homes with three or more air conditioning systems, or light commercial applications, may require a liquid-cooled generator. See also: Air-Cooled vs Liquid-Cooled Standby Generators.

For most home units, the engine is slightly larger than a riding lawnmower engine. It has two cylinders, two spark plugs, an oil filter, oil, an air filter, and a large battery, similar to a car.  Annual maintenance is needed to keep it running in tip-top shape, including a quick oil, filter, and spark plug change once per year.

3. Fuel

Most homeowners fuel their generator with natural gas. When natural gas is not available, propane is a reliable alternative. Generac standby generators are factory-configured to operate on either fuel type.  When connected to natural gas, the generator can run indefinitely and will continue operating until utility power is restored. With propane, runtime is dependent on tank size, generator size, and electrical load. As a general guideline, a 200-gallon propane supply will provide approximately 3 to 5 days of runtime under typical household usage.

3. WiFi Connection and Monitoring

Generac standby generators include built-in Wi-Fi AND cellular monitoring that allows homeowners to check their system status through a mobile app. The app provides real-time updates on generator operation, maintenance reminders, and alerts for any issues, even when you are away from home. During an outage, homeowners can confirm the generator is running and supplying power, and when utility power is restored, the app reflects the system returning to standby. Cellular monitoring ensures connectivity even if your home’s internet service is disrupted during a power outage.  Kohler home standby generators have a WiFi option for purchase that requires a small fee for equipment and installation.  Guardian Home Generators can also monitor your Generac generator for you!

  

4. Weekly self-test, AKA exercise cycle 

To ensure reliability, the generator runs it's engine automatically performing what is called "exercising".  This self-test is usually weekly, but can be changed to meet your unique needs.  These tests run the generator briefly to check for any issues, ensuring it's ready for the next outage and it keeps the engine lubed and in good working condition.

Benefits of Whole-Home Generators:

  • Automatic Operation: No manual intervention is required during outages.
  • Fuel Options: Our generators are powered by natural gas or propane.  No messy, dangerous gas cans to deal with.
  • Comprehensive Coverage: Can power the entire home or selected circuits, depending on the system size.
  • Cellular and WiFi Monitoring:  All of our Generac Home Generators come with a built-in Cellular and/or Wifi module to make programming and monitoring easy.
  • Peace of Mind: Ensures essential systems like heating, cooling, refrigeration, and medical equipment remain operational.


Investing in a whole-home backup generator provides uninterrupted power, safeguarding your home and comfort during unexpected outages.