In message , David Hansen
writes
On Tue, 28 Aug 2007 03:07:36 -0700 someone who may be
wrote this:-

The fuse in the fusebox next to my central heating controller keeps
blowing. I replaced it twice yesterday with a 3A fuse and again this
morning with a 5A fuse and within half an hour of the heating coming
on and the radiators just starting to get warm it blows.

The fuse blowing is trying to tell you something. Find out what it
is, rather then hoping for the best.

Has anyone got any ideas as to what the most common causes could be.

In addition to the water suggestions, perhaps a cable or bit of
equipment is damaged.

Someone with more experience could measure and work out where the
fault is likely to be.

There's no way that most people would ever find this fault unless they
have been listening to my words of wisdom over the years grasshopper

It's a fairly subtle fault - the boiler switches on, the fan motor
starts up, the windings overheat and go short circuit, fuse pops,
windings cool down by the time you get round to measuring them and
revert to closer to a normal resistance

so, unless you are particularly on the ball, you won't find it

The opposite can also happen, some of them have resettable thermal fuses
which means that the fan cuts out and by the time you get around to
measuring the winding resistance, its back to normal

a devious cove is the fuelsaver fan

--
geoff