On 18 June, 14:45, "DIY" wrote:

850watt 2 stroke generator would be powerful enough to power the condensing
combo boiler to give us hot water (maximum power consumption 140watt) and
maybe some small electrical appliances all well under 1kw?

Yes, but a bad idea IMHO.

Go for an inverter to power the boiler, but use a decent one with a
reasonable output waveform and test it beforehand. Otherwise just
don't bother - set up alternative hot water supplies instead as I
doubt you'll need heating. A big insulated plastic "tea urn" cooler
can be handy here, especially if it has a tap.

A British Army "Boiling Vessel" (look it up) is a great gadget for
this situation, and will run off a pair of car batteries. Try eBay or
a big (on-line) surplus shop

For the fridge, use "stored cold" in freeze packs.

Anything else, use a primary power source rather than generating
electricity and then using that, i.e. oil lanterns or candles, gas
stoves for cooking / hot water, wood stove for warmth.

Generators are noisy. If you really must, hire a _quiet_ 4 stroke,
rather than buying a Happy Shopper 2 stroke or a 2kW builder's genny.
The "market trader" gen sets are a lot better noise-wise and most hire
shops will have one.