On Sun, 4 Nov 2012 14:11:05 +0000 (UTC), Harry Davis wrote:

Are all the electrics for an oil central heating and hot water system
(pump, timer, stats, etc.) usually all off a dedicated mains fuse? Or
all on the same fused spur from one of the rings?

Or is it common for one of the appliances to be on one ring, another on
another, etc.?

The entire heating system should be fed from a single fused supply, be
that from a ring or direct from the CU. There are so many things
switching things on/off based on time or temperature that to have things
fed from multiple supplies would be down right dangerous. You might think
you've isolated something and test it, but time passes or the temp
changes and your "dead" circuit becomes live...

I'd like to have the electrics for the heating system on their own
plug, which could be plugged either into a mains socket or a socket
powered by another supply.

That's what I've had here for quite a while, unswitched socket and 3A
fuse in plug top. Absolute isolation of all heating related stuff when
unplugged (the plug is next to the board with all the stat receivers,
time switches, solar controller etc). Enables it to be plugged into
extension lead from generator when the mains fails.

--
Cheers
Dave.