Key takeaways
- Generac rates the Guardian 26kW at 26,000 watts on propane and 22,500 watts on natural gas, so a house on natural gas should size from the lower figure.
- What a 26kW can run is decided by your load list: what has to run at the same time, and how much extra current each air conditioner draws as it starts.
- Homes with two central air systems are the usual reason to look at the 26kW, and load management can let both share the generator in turn.
- If the load list is larger than the 26kW's rating, the next conversation is a larger liquid-cooled or commercial unit, sized the same way.
What can a Generac 26kW run is the question we hear from owners of larger San Antonio homes, often ones with two air conditioning systems, a pool and a full kitchen. The 26kW is the largest size in Generac's Guardian home standby line that we list, and it carries a lot. But no generator size answers the question on its own. The answer comes from your house: what you want running at the same time, and how those loads start.
Start with Generac's own ratings
Generac rates the Guardian 26kW at 26,000 watts on propane and 22,500 watts on natural gas. That gap matters. A generator running on natural gas makes less power than the same generator on propane, and most homes in the San Antonio area that have a gas meter are on natural gas. If yours is, the figure to size from is 22,500 watts, not 26,000.
The 26kW uses Generac's G-Force 1000 engine, carries a 110 amp main line circuit breaker, and weighs 518 pounds, all according to Generac's product page. The weight is part of why placement and the pad are planned before install day.
The full table, with links to Generac's product page and spec sheet, is on our Generac 26kW generator page.
Why a load list, not a square footage, decides it
Square footage is a rough guess at best. Two houses of the same size can need very different generators: one has gas cooking, a gas water heater and one air conditioner, and the other has an electric range, an electric water heater, two air conditioners and a pool pump. The second house needs far more power to run the same way in an outage.
A load list names every load you want to keep, its running draw, and the extra current it pulls for a moment as it starts. Motors are the loads that matter most here. A central air conditioner's compressor draws several times its running current for a split second at start up, and the generator has to carry that surge on top of everything else already running.
- Central air conditioning, one or two systems, and how each one starts
- Refrigerators, freezers and any well or sump pump
- An electric range, oven, dryer or water heater, if you want them in an outage
- Pool equipment, which many owners choose to leave off
- Medical equipment and a home office
Two air conditioning systems
Homes with two central air systems are the most common reason the 26kW comes up. In a Texas summer outage, the air conditioning is what people want most, and two systems starting at the same moment is the hardest load a home generator faces.
There are two ways to handle it. One is to size the generator so both systems can run and start together. The other is load management: a control that lets the generator carry the systems in turn, holding one off until the other has started, or shedding a large load when the generator is near its limit. Load management can keep a house on a smaller unit than its total load list suggests, but it means something waits. Which way fits depends on how you live in an outage.
How the switch and the load management fit together is covered in our guide to generator transfer switch types.
When the 26kW is more than the house needs
Bigger is not automatically better. A generator sized well past the load list costs more to buy and install and runs lightly loaded most of the time. If your list fits inside a smaller size, the smaller size is usually the better buy.
Generac's 22kW is rated 22,000 watts on propane and 19,500 on natural gas, and the 24kW 24,000 and 21,000. Our Generac 14kW vs 22kW vs 26kW comparison puts the published figures side by side, and the Generac 22kW generator page has its full table.
When the load list is larger than the 26kW
Some houses list more load than the 26kW is rated to carry: very large homes, homes with several air systems, or properties with shops, barns or a guest house on the same service. At that point the conversation moves past the air-cooled home standby line to larger liquid-cooled units or commercial generators. Those are sized the same way, from the load list, but the unit, the transfer equipment and the installation are a larger job.
For properties that run like a business, our commercial standby generator page covers how those systems are planned.
Fuel, placement and the gas line
On natural gas, the gas meter and the line from it have to supply the generator at full load while the house's other gas appliances run. That is a question for the utility and a licensed plumber. Gas line and gas connection are not included in our electrical price. That is a licensed plumber's work and we quote it separately, and we coordinate the plumber so the gas and the electrical work happen together.
Placement follows the setbacks from windows, doors and the property line that the code and the manufacturer set, on a pad that suits the unit's weight. Both are checked before the price is written, so they are known rather than found on install day.
Make a rough list of your own first
Before a sizing visit, it helps to walk the house and write down what you would miss most in a long summer outage. You do not need the wattage of anything. You need the list, and a sense of what has to run at the same time. An electrician turns that list into numbers by reading the nameplates on the equipment and checking the panel.
- Which air conditioning systems have to run, and which rooms they serve
- Whether the water heater, range, oven and dryer are gas or electric
- Any pool, spa or well pump, and whether it needs to run in an outage
- Anything medical, and anything for work that cannot stop
- Anything new since the house was built, such as an EV charger or a shop
That list usually sorts a house quickly. If gas does the cooking and water heating, the 26kW often has room to spare even with two air systems. If those loads are electric too, the list may put the house right at the 26kW's rating on natural gas, or past it, and the plan becomes load management or a larger unit. Either way, the answer comes from your house, not from a chart.
What the installed price includes
An installed 26kW is the unit plus the transfer switch, the wiring to your panel, the gas line, the placement and the electrical permit. What moves each part is in our Generac generator cost guide. We sell and install Generac home standby and commercial generators, and the installation itself is described on our Generac generator installation page.
Get your load list done
The fastest way to know what a 26kW would run in your house is a load list made in your house. Our free Generac sizing visit lists your loads with you, checks the panel, the service and the gas meter, and recommends the size, whether that is the 26kW or a smaller one. You get a written price after it, and there is no obligation. Everything else we install is on the Generac generators page.