In article ,
Set Square wrote:
With the likely prospect of the National Grid not coping if we get a
cold spell, I am looking seriously at providing a simple means of
powering the electrical bits (boiler control/pump/3-port valve) of my
gas central heating system, plus a couple a freezers and a few lights.

I've just finished testing mine. I've installed a double pole changeover
relay in the output from the FCU that feeds the central heating - the coil
of that relay being energised by the mains. If the mains goes off, it
connects to a 150 watt invertor I've just made - using a Vellerman kit as
the basis. It runs off a car battery. It's been on since about 12 o'clock
and the battery is still fine.

At the moment, it's not *totally* automatic, as the invertor has to be
switched on even if left connected to the battery. I might add a second
relay to switch it on when the mains dies, but that would only be strictly
necessary if I wanted the heating to work if I was out when the power
failed.

I'm happy to rely on torches and battery radios etc for the duration of
the cut, as I have a gas hob for any essential cooking.

--
*Husband and cat lost -- reward for cat

Dave Plowman London SW 12
RIP Acorn