Mike wrote:
After yet another power cut whilst I was out, I think I need to put UPSes on
some critical items, namely the fridge and freezer, certain lighting and the
heating. The cuts are never more than 4 hours as then I could claim
compensation so in theory the Belkin range seem to fit the bill.

In that case, you certainly don't need a UPS on the fridge/freezer, in 4h
they won't appreciably warm.

As you need to budget for the fridge and freezer motors coming on together,
you are looking at somewhere around 3KW surge, which is quite a large one.

What I'd do is to place the UPS on a FCU, and run a low-load circuit
from the output (another FCU?).

Now, depending on what you are using for lighting (if you've got 2Kw
of lights, or you've gone all energy saving, answers are different),
I'd then connect the existing lighting circuit to this, and attach a few
2A sockets to this.
The boiler goes into one of the 2A sockets.

This then lets you (for example) plug a TV into a 2A socket, if you want to,
or to add a generator (add a switch for the UPS to take input from mains
or generator.

You may even want to consider if you really want the boiler on the maintained
circuit.
In 4h you're probably not going to get that cold.

It might be better if you can have a switch to pick between mains and
maintained.
Unless you've got unlimited battery, you want to be able to ideally
start off with as low a load as possible, then add load to it, rather
than (for example) coming back 3h into a power cut and finding that all
the lights have just about drained the batteries, and you now can't watch
TV.