My existing 3 position valve motor is goosed. I’ve bought a new valve head which has the following wiring:

White = Heating on
Blue = Neutral
Grey = Hot water off
Green/Yellow = Earth
Orange = Boiler and pump live

The existing valve wiring is colour coded as follows:

What’s confusing me is the beige coloured wire. I’m assuming this was once white and isn’t a faded brown (i.e. potentially the live). I can find no online reference to any alternative colour coding for these valves. But the existing one is old.

So, my question is do I take beige for white and just straight swap or am I risking blowing something up?

Have a look in the wire centre and see what colours you have on the end of the black cable coming out of the Honeywell head, that’s where your be disconnecting it from anyway.

when I replaced mine I think it was just a case of swapping the wires one at a time in the junction box after replacing the whole head

The junction box is boxed in to the corner of the airing cupboard with no access panel. So, without cutting a hole in the wood panel, I can’t access it. My plan was simply to cut the existing valve off at the valve end and use a terminal block/chocbox to connect the new valve and protect the connection.

When I expose the existing wiring beneath the cable jacket, I’ll be able to see if the beige wire is actually a discoloured white. But I wanted to sanity check my assumption before I start cutting.

EDIT: I’ve also emailed Honeywell to ask if they have the wiring schematic for my existing valve, but all they could provide was the current schematic – the same as included with the replacement valve

I’ve googled everything I can think of and can find no schematic that has anything other than the white etc. listed in my OP.

My fall back position is the cannibalise the existing valve and check which wire is connected to the resistor. That should at least confirm which wire is the live!

Orange and grey are typically pump / boiler control, blue neutral, so the other two will command valve position. It’s all 240v (usually…) so after you’ve wired it up either it’ll work first time or the heating / hot water control will be reversed.

If you’re still not convinced, the easiest way to check is to install your new junction box but don’t connect the motor head, then turn on the heating / hot water one at a time and check for 240v. One or two will be live, depending on how your system is wired. You will need a meter, a voltage detector pen won’t work.

Orange and grey are typically pump / boiler control, blue neutral, so the other two will command valve position

Yes, blue is neutral. On the new valve, orange is live. I appreciate that if I get live, neutral and earth right then it’s 50/50 with the other two. The question is about certainty over which of the existing wires is the live – beige or orange.

You can just replace the Synchronous motor on its own if the rest of the valve is in good working order.

http://www.screwfix.com/p/drayton-synchronous-motor/28670

Ha, perfect! I’ll just do that and return the valve head. Much easier!

Your new valve should have the following:-

O = Orange wire – common contact connected to permanent live.
G = Grey wire – normally open contact (pump & boiler)
W = White wire – normally closed contact (not used)
BR = Brown wire (switched live from timeclock/stat
B = Blue wire (Neutral)

Your old valve looks like it had a one way auxiliary switch instead of two way as the new one is. Make sure you connector block & tape up the white wire as it will be live when the valve is not energised.

Sorry that was for a 2 port valve.

Just changing the motor assumes the valve internals are OK and that the micro switches are not the cause of the problem.
Agree though, try the motor change 1st.