Key takeaways
- Generac's published ratings put the Guardian 22kW at 22,000 watts on propane and 19,500 watts on natural gas.
- A Generac 22kW is often enough for most of a typical house, including central air, when the largest loads are managed.
- Generac sells the 22kW with a 200 amp smart switch for up to whole house protection, so load management is built into that package.
- On natural gas the rating drops by 2,500 watts, which is the figure to size against on a natural gas house.
What can a Generac 22kW run is the question behind most standby generator decisions, because the 22kW sits in the middle of the line. Generac's published ratings put the Guardian 22kW at 22,000 watts on propane and 19,500 watts on natural gas. For a typical San Antonio home, that is often enough to run most of the house, central air included, as long as the largest loads take turns. This guide explains how that works and where its limits are.
The ratings, engine and weight Generac publishes are on our Generac 22kW generator page, with links to Generac's product page and spec sheet.
Why the 22kW is the common middle
Smaller units are sized for essential circuits. Larger units are sized for big homes with several air conditioning systems. The 22kW sits between them. It has enough capacity to carry one central air system with room left for the kitchen, the lights, the outlets and the pumps, and with load management it can serve a whole panel without the owner choosing circuits ahead of time.
That is why it is the size people mean when they say whole house generator. It is not that it runs every appliance at full tilt at once. It is that, managed well, the house works close to normal through an outage.
The switch Generac sells with it
Generac sells the 22kW with a 200 amp, NEMA 3R smart switch for up to whole house protection. NEMA 3R is an outdoor rated enclosure. The smart switch is what makes the whole house approach practical: it moves the entire panel to the generator and manages the largest loads so the total stays inside the rating.
Whether that 200 amp switch suits your service is part of the sizing visit. A house with a larger service, or one where an essential circuit switch makes more sense, may be wired differently. The point of the visit is to match the switch to the house, not the house to the package.
Our guide to generator transfer switch types lays out the choices side by side.
How load management works on a 22kW
Load management watches how much power the house is drawing from the generator. When a large load like the air conditioner, the water heater or the dryer would push the total past the rating, the system holds one back until there is room. When the load drops, the held appliance runs. Most of the time the household never notices which load is waiting.
- The air conditioner is usually kept as the priority, because cooling is why most Texas homes buy a generator.
- Electric water heaters, dryers and ranges are the usual loads that wait their turn.
- Pool pumps and spa heaters are often set to wait as well, or left off the generator.
- The refrigerator, lights, outlets and the internet run normally throughout.
The nameplate on each appliance gives its running watts, and the air conditioner's data plate gives its starting current. Those are the figures we use to decide which loads are managed and in what order.
Natural gas or propane on a 22kW
The gap between the fuels is larger on the 22kW than on the smaller sizes. Generac lists 22,000 watts on propane and 19,500 on natural gas, a difference of 2,500 watts. On a natural gas house, 19,500 watts is the real ceiling, and load management has to be set up against that number.
On natural gas, the gas meter also has to supply the generator on top of the furnace, the water heater and the range if they run on gas. Checking that is a licensed plumber's job, and so is running the line. It is quoted separately, and we schedule it with the electrical work.
More on choosing between the fuels is in natural gas vs propane standby generators.
When the 18kW or the 24kW fits better
A smaller home with one central air system and no electric cooking may not need the 22kW. Generac rates the 18kW at 18,000 watts on propane and 17,000 on natural gas, and that can be enough. A larger home, or one with two air conditioning systems on natural gas, may need more headroom than load management can give. Generac rates the 24kW at 24,000 watts on propane and 21,000 on natural gas.
See what can a Generac 18kW run and what can a Generac 24kW run for the sizes either side, or every size on our Generac generators page.
Setting the order of what waits
Load management is only as good as the order it is given. At the install we set which loads are protected and which loads wait, and in what sequence they are allowed back on. In most San Antonio homes the air conditioner is protected, because cooling is the reason for the generator. The refrigerator, the lights, the outlets and the router are never managed, because they are small and they matter.
The loads that wait are usually large and forgiving. An electric water heater holds its heat for hours, so waiting a few minutes changes nothing. A dryer can finish a cycle later. A pool pump can run when the air conditioner cycles off. Setting the order this way lets a 22kW serve a whole panel without anyone in the house managing it by hand.
What a 22kW does in an outage, minute by minute
When the utility fails, the transfer switch senses it and signals the generator to start. Within seconds the generator is running and the switch moves the house over. The protected loads come on first. As the generator settles, the managed loads are allowed back as there is room for them. When the utility returns, the switch moves the house back and the generator runs on for a short cool down before it stops and returns to standby.
On a 22kW sized well, the household notices the lights blink and the air conditioner pause, and then the house carries on. If the generator is undersized or the order is set badly, they notice the lights dipping every time the compressor starts. That difference is the whole reason the sizing visit reads the plates rather than guessing.
If the household changes later, with a pool, an electric vehicle charger or a workshop, the order can be revisited. A load added to the panel is a load the generator may be asked to carry, so it is worth a call before it goes in.
What the install involves
We set the unit, install and wire the transfer switch at the service, pull the electrical permit, and start the unit up and test it under load, including a transfer to make sure the managed loads behave the way they were set. The gas line is a licensed plumber's work and is quoted separately.
The full process is on our Generac generator installation page. We sell and install Generac home standby and commercial generators, and you can book a free sizing visit to see whether the 22kW is your size.
What a 22kW costs
The installed price is the unit, the switch, the wiring, the gas line, the placement and the permit. A whole house install at the service usually involves more work at the panel than an essential circuit install, and the distance from the unit to the panel and to the gas meter moves the price as much as the unit does.
Each part is explained in our Generac generator cost guide. We write your price after the sizing visit.