Dear All,
Our central heating controller is on the blink.
How straightforward is it to replace this myself?
The programmer is a Honeywell unit, no model number shown, and I don't know how old it is. The front section hinges up and separates from a smaller piece screwed to the wall to allow access to batteries and a reset button.
The wall section has terminals labelled T3, T4, T7, T8 which the front snaps onto. The unit is roughly 8 by 13 cm.
My questions are:
If I buy a new Honeywell unit like the one here
(a) Simply snap on the the existing wallmounted section (this would be great)
(b) Require the same four wires as I have in the wall now, but require me to connect them anew to the new unit (this would be fine)
(c) Require different wires from what I have now (this would be a nightmare!)
Any and all advice gratefully received!