Set out yesterday to replace my Randall 922 CH controller from the early '90s. (No longer possible to program its memory.) When I installed it, I understood it had the industry standard backplate, so was a bit surprised yesterday to find that the Tempus replacement had an entirely different "industry standard backplate". Of course, this was only apparent when I got home and into the blister pack...
So I'm off again, but this time with a photo of my old "standard backplate" to help me choose the replacement.
Whilst there was something of an attempt to get all the manufacturers to use the same _type_ of back plate. The whole scheme falls down because:
a) The back plate usually wasn't the method of mounting for the old controller. b) The most likely time to change the controller was when the heating system has an overhaul. Whereupon a completely new type of controller may need to be added elsewhere. c) The replacement control usually has the plate in a different position relative to the body of the control. You then find the new controller clashes with i) door frame. ii) kitchen cupboard iii) light switch iv) socket v) corner of wall.
d) even the same sort of controller (e.g. 2 channel) would have differing connections some with volt free changeovers , some with earth, some with on signals only etc.etc.etc.
Essentially I have never yet come across a job where these back plates have been the slightest use. The only time they come in handy is with like for like replacement on Randall rotary timers. [And the only reason I'm replacing like for like, with something twice the cost of the modern equivalent, is because the customer wants it that way].
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