Replace c/h analogue timer

12 Oct 2009
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United Kingdom

how easy is it to replace a central heating timer switch (old analogue style) with digital one?

is the wiring similar for a straight replacement or does it all depend on the combi boiler and what is being replaced?

i have a ravenheat combi boiler, old style timer with separate thermostat..

thanks in advance!
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Usually it's fairly easy. Sometimes they can be a straight swap, like for like. If not identify the existing wires before removing them. Most likely as follows:

Permanent live (from the FCU)
Central heating "on" live

Reconnect them to the appropriate terminals on the new programmer.

If you could advise the make and type of programmer that you have, the connections to it and the one you are considering, maybe someone could give you more specific information.
thanks for response - current timer is a switchmaster sm300 although didn't have time to check the connection as yet, i'll do that tonight, if i can..
I think that Switchmaster is a Drayton/ACL brand.

If you go to the Invensys website you can eventually get to their UK heating controls page.

If it has an industry standard backplate, you can fit one of their newer digital controls, and they have a table of how to convert from one to another saying if connections are same or need changing
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