A couple of years ago our central heating timer developed an independent
streak and started stopping and starting when it felt like. Very annoying
when you come home from work on a cold day expecting that the heating had
been on for an hour or so only to find it all off. So we gave up with it
and switched the heating on and off at the mains switch which at least you
can rely on although obviously not as convenient. However we actually got
round to deciding to replace the timer and today a lovely new one was
fitted. However, it is still no better. At the moment I can hear the
boiler roaring away yet the timer is showing off, no lights or anything.
It's due to come on at 4.30. I'll have to switch it off at its main power
switch again in a moment.

Can anyone suggest what the problem could be? The electrician said that two
extra wires came into the box, probably from the open fire thermostat which
has a back boiler but just heats water not rads. I'm wondering if the
problem is
something to do with that, in which case I haven't a clue where that
actually is or how it is replaced if faulty.

Not sure what info anyone might need to help diagnose this - it's oil
central heating, the timer controls the boiler, ie everything, no separate
controls for water and heating, there is no room thermostat, we just have to
go round turning the radiators on and off to control things.

Help please!! Thank you

Liz