The Wallport wrote:

from the rear and if so these are completely inaccessible. The people
who did this have cut a hole in a wall tile and so you cant get to the
very back of it. Anyone know how it is mounted?

Often there is a small screw top or bottom that secures the front to the
mounting plate. However if someone has tiled round it that may be obscured.

If all else fails, turn off the boiler, and clomp the switch on the side
with a club hammer! ;-)

When I do get to the back, what model can I replace it with? Are these
things fairly standard?

Assuming it just turns the boiler on and off at preset times, and does
not have separate controls for differentiating between hot water and
central heating, most are pretty standard. If you have the manual for
the boiler it may show some typical wiring diagrams.

Usually all a timer does is close switch when its in the "on" part of
the cycle, and open it otherwise.

So you may have two, three, or four wires. A four wire setup would be
Live, neutral and earth to the timer - this gives it power to run. Plus
a switched live which it will connect to the supply live when it is set
to "on". It may not have earth, it may not have neutral (although that
would normally require it to have a battery to keep its clock running)

Some clues would be appreciated. I have replaced a timer in a previous
house but that was dead easy - nothing like this!

This is probably as easy once you get it off the wall.

It might even be worth removing the switch altogether and replacing the
room stat with a programmable one. That way you not only get the
programmable on/off switching throughout the day (or week) but also the
ability to vary the temperature throughout the day at the same time.

After recommendations from this group, I fitted one of these the other
day, since my new boiler did not have any timer of its own:

http://www.screwfix.com/app/sfd/cat/...12157&ts=45911

Works very well.

--
Cheers,

John.

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