Tina,
I run a 800watt output micowave on a 2KW generator along with the water heating and battery charging without problem.
Hello Rod,
If you have a combined Gas/mains water heater, then heating water by generator is a very expensive way of doing it.
The figures go like this; Gas consumption for 1.2kW burner is 83gm per hour. Heating takes about 20Min so gas used is about 28gm.
Electrical elements are typically rated at 800W and take about 30 min to heat water. The fuel used will be about 400ml (about 300gm).
The difference in heating efficiency is down to the fact that gas appliances have to be at least 70% efficient at turning gas into usable heat. The electrical element is of course virtually 100% efficient as it is immersed in the water, but the best portable petrol generators are at best 14% at converting fuel to electricity and typically only 8 to 10%
Don't forget that the gas is shut off when the thermostat operates so no gas is used until the the thermostat calls again, unlike the the generator which continues to run even when the water heater T/Stat has turned off the element.
Moral: if on mains hook up - use mains to heat water, run the fridge, but if you need generator, use gas for water heating and running the fridge - its much quieter, uses less fuel and benefits the environment and you pocket.