If you can afford it...Get an "Inverter Model".
- 1) They generate a higher quality AC Waveform.
- 2) When the load gets smaller, the engine can throttle back to save fuel, but the Alternating Currents remains in spec.
If you are running the AC off the generator the AC Waveform will be higher quality with a constant 120V if you're in the US. That's because the engine has to work to provide enough power. This assumes the generator is powerful enough and you feed into the house in a way where the air conditioning can also run off the generator. I back-feed into the house via a 4-prong welding receptacle with a 60A breaker and everything has power. I use a suicide cable. Only do this if you know what you're doing because it can kill you and is illegal, but many people do it. It's basically a cable with a male plug on both ends.
I use it like this:
1. Turn off main house panel breaker so it is disconnected from the grid.
2. With the generator off, I plug the suicide cable into the generator and welding receptacle.
3. I turn off the breaker of the welding receptacle. I also turn off the subpanel where the breaker is housed.
4. Turn on the generator and let it run for about 30 seconds to settle in.
5. Flip the welding receptacle breaker so the generator back feeds into the sub panel.
6. Flip the subpanel breaker so it back feeds into the house panel.
The house now has power everywhere. I have a whole house surge protector installed and computers run off UPS backups. Note though that the UPS backups will go on battery when the generator has limited load on it because it won't be a clean power supply. If you add an air conditioner load to the generator the UPS backups will accept the power supplied by the generator because the voltage will remain stable at 120V. You can also get Online (Double Conversion) UPS backups that won't have issues with generator power but they cost a lot and are noisy because they have fans that run 24/7 even when connected to the grid.
https://www.backupbatterypower.com/collections/online-double-conversion