"Thomarse" wrote in message
ups.com...
Hello,

I have an old mechanical central heating control unit made by SMC. It
has stopped working, the dial no longer goes round, so I cannot set the
timer and also I cannot switch between hot water and central heating,
as whichever setting I have the switch on I get both hot water and
central heating.

I haven't the same problem as you but I've just replaced a digital timer
that required a degree in electronics, the instruction manual and at least
two new swear words everytime you wanted to change the programme. I replaced
it with a nice new analogue mechanical timer made by Horstman and am very
happy indeed.

I discovered that the old timer had the wiring identification on its rear
(hot water demand. hot water satisfied etc etc) and it was a very simple job
to swap wires over like for like, especially as the new timer came with
standard wiring diagrams for umpteen other controllers.

Be brave, give it a go!

Julian.