Wiring problems for 2-port zone valve actuator

[learning4fun]

Hello everyone. I have a fully pumped small bore S-plan system controlled by a programmer, cylinder stat and room stat, and two 2-port motorised zone valves.

The actuator controlling my central heating zone valve has failed and I need to replace it, however, the closest type of replacement I have doesn't have the same number of wires (and the wire colours are different). I'm sure the valve is of the correct type but I assume wiring standards have changed since the installation of my system.

The faulty zone valve actuator (sunvic) has five wires: blue, orange, yellow, white, and green/yellow.
The new zone valve actuator (danfoss randall) has four wires: blue, brown, orange, and grey.

Would anyone please be able to tell me how the wires of the new actuator correspond to those of the older faulty actuator, in simple terms please for ease of re-wiring, e.g. orange wire (on old actuator) goes to ... on new actuator.

Thanks very much for your time.

 

[EliteHeat]

Blue - neutral
Brown - switched live from programmer / room stat
Grey - permanent live
Orange - switched live from microswitch - powers pump & boiler

 

[learning4fun]

Blue - neutral
Brown - switched live from programmer / room stat
Grey - permanent live
Orange - switched live from microswitch - powers pump & boiler

Thanks 'NotBovvered', for your reply. At least I know what the wires on the new actuator represent now! Could you tell me what the wires on the older (faulty) actuator represent also please ... this will help me match up the wires when I make the exchange.

Thanks very much

 

[EliteHeat]

Dunno - to be honest I wouldn't worry about the old wiring. Personally I would trace evrything back from the wiring centre and concentrate on wiring the new valve in correctly.

However, if I were to guess (and I am) I would think .....

Blue - neutral
Green/yellow - earth
orange - to boiler & pump
White - switched live from room stat
Yellow - permanent live

But don't take my word for it - trace it back

 

[learning4fun]

I will trace it back. Thank you so much for your help.

 

[ChrisR]

Whoa. Sounds like you may have an old Sunvic SM head, on an ML brass body?
These are motor-open motor-close valves and not compatible at all with the spring-return ones (eg sunvic SZ) more used today.

Find the number and we can go from there.

 

[learning4fun]

Whoa. Sounds like you may have an old Sunvic SM head, on an ML brass body?
These are motor-open motor-close valves and not compatible at all with the spring-return ones (eg sunvic SZ) more used today.

Find the number and we can go from there.

Hello. Yes, your description is accurate. The number on the dated (faulty) sunvic actuator is SM5203. I was hoping to trace back the wiring to the junction block but perhaps I should hold out for your thoughts on this ... if it's not a compatible replacement!

Thanks for your help on this.