2port zone valve wiring connections?

[Mister Banks]

I have a couple of Honeywell 2 port motorised valves on my s plan system, one is a 5 wire and the other is a 6 wire. Both valves work ok so I don’t have an issue but I am a little confused as to why all the online s plan wiring guides I have seen show the grey wires going to live and the orange wires going to switched live on the boiler. The connection diagram on the 6 wire valve shows it the opposite way around!

 

[kidgreen61]

It doesn't really matter which way they go, what happens is that as the valve opens, a microswitch is closed which connects grey and orange together.

 

[Mister Banks]

It doesn't really matter which way they go, what happens is that as the valve opens, a microswitch is closed which connects grey and orange together.

It matters with the 6 wire valve because the white will not get any power unless the live is on the orange.

 

[Johntheo5]

I think that white wire can be used to give a open indication of the valve, if so, then it shouldn't be live until the valve has opened, I think the grey wire is the permanent live to these valves? If so then the orange and the white will be live when the valve is opened.

 

[Mister Banks]

I think that white wire can be used to give a open indication of the valve, if so, then it shouldn't be live until the valve has opened, I think the grey wire is the permanent live to these valves? If so then the orange and the white will be live when the valve is opened.

On the 6 wire valve the permanent live is the orange wire according to the connection diagram on the valve. This is different to the diagrams for an s plan I see online.

 

[MNW67]

On the 6 wire valve the permanent live is the orange wire according to the connection diagram on the valve. This is different to the diagrams for an s plan I see online.

I thought 6 wires were used for C-Plan? Is the 6 wire valve a 28mm?

 

[Mister Banks]

I thought 6 wires were used for C-Plan? Is the 6 wire valve a 28mm?

Yes it is, the white wire isn’t used in my case.

 

[MNW67]

Yes it is, the white wire isn’t used in my case.

All the diagrams I have seen show the grey wire going to NO. The same as the photo you posted?

I can't see any difference between your photo and the diagram below.

 

[Mister Banks]

All the diagrams I have seen show the grey wire going to NO. The same as the photo you posted?

I can't see any difference between your photo and the diagram below.

View attachment 338198

This diagram shows it slightly different, the com is grey and the NO is orange. I know it doesn’t matter as in effect the result is the same.

 

[CBW]

It matters with the 6 wire valve because the white will not get any power unless the live is on the orange.

See note number 2

 

[Mister Banks]

See note number 2

Thank you, I have seen that and ensured the white is safely isolated, which is more than the original installer did!

 

[Johntheo5]

Its for a C plan where the pump is switched off for a gravity HW system, the valve is on the cyl coil.

KCS UK

 

[Exedon]

Last week I replaced the head on a old drayton 1in zone valve.
Couldn't access junction box buried beneath a laminate floor.
Carefully cut cable so I could joint box it found 7 cores !
Normal 5 plus 2 white.

 

[MNW67]

Its for a C plan where the pump is switched off for a gravity HW system, the valve is on the cyl coil.

So with C-Plan, when there is a demand just for CH, the signal from the room thermostat goes along the white wire to the zone valve (which is on the gravity cylinder flow from the boiler) and then out again along the orange wire to the boiler? That's pretty neat. I hadn't realised before exactly how it worked.

But why doesn't it just go straight to the boiler on terminal 10. What is the purpose of looping it through the zone valve?

 

[Johntheo5]

Is it because the cyl coil is gravity fed so with the CH only on, boiler+pump, and if HW is requested, the mot.valve opens, the boiler stays running but the circ pump stops as there is no power now to the white wire, a sort of (un pumped) HW priority.