Replacement Cental Heating Controller-Wiring Colours

[simmyjiff]

Hi,
My CH controller bunt out on Friday, it was an old Smith's industires type, my local stockist has recommended replacing it with a Honeywell ST9400, I'm also replacing the roomstat with a Honeywell 6360. Looking through the installation diagrams, particularly the wiring I notice that I have different wiring colours for the 3 port motorised valve, which again is old, (I think!) and is a SwitchMaster. The wiring colours of this are white, yellow and orange, green & yellow (earth) and red & black, (live & Neutral), whereas on the Honeywell diagram the colours are Blue, White, Grey, orange and Geen & Yellow, quite different! which of the new colours corresponds with the old ones, or is it not that simple? Should I also replace the Valve, if so what shoud I use? The current one has 3 settings, Hot Water, Central Heating and Hot Water/Central heating.
Thanks

 

[crockett]

When you purchase your new programmer, it will come with a wiring diagram. If you can read it ok, then you will have to familiarise yourself with the wiring, knowing which cable goes to what component, etc. in your wiring centre. This will then inform you which colour wire on your motorised valve is controlled by what other component, i.e. room stat, cylinder stat, etc.

Hope this helps. Someone else will inform you exactly what the cables will do, but you may find this hard to follow.

 

[D_Hailsham]

... Switchmaster ...The wiring colours of this are white, yellow and orange, green & yellow (earth) and red & black, (live & Neutral) ... Should I also replace the Valve, if so what shoud I use? The current one has 3 settings, Hot Water, Central Heating and Hot Water/Central heating.

There is no need to replace the valve if it ain't broke
You do have to modify the wiring from that shown in the Honeywell diagrams.

You have only listed 5 wires on the Switchmaster, which usually has six; or is "yellow and orange" meant to mean two separate wires? If so, read on!

The standard Y-plan wiring is this:

The Switchmaster wires do the following:

Red - switched live to pump boiler: connect to terminal 8 in above diagram
Orange - HW ON: connect to terminal 9 in diagram.
White - HW OFF: connect to terminal 7 in diagram
Yellow - CH ON: connect to terminal 5 in diagram
Black - Neutral: connect to terminal 2 in diagram
Green/Yellow - Earth: connect to terminal 3 in diagram

The wire from HW Stat Terminal 1 to terminal 8 needs to be moved to terminal 9. i.e HW Stat 1 connects to terminal 9