mid position valve wiring question for y plan

[jpgibbo]

i have a fault on ch system. It is a conventional y plan system and the fault is the ch radiator get hot when only hw is called for. I have checked wiring and it looks to follow the honeywell circuit diagrams for the mid position valve and y plan system.

the instructions state that for just hot water there should be no power to the valve and thus closing port A and central heating. But on electrical drawing the cylinder stat call on (wire 1) is connected to the orange wire on valve which is also connected to pump and boiler live so you always get a supply to orange wire on valve when you call for hot water thus supplying valve with power and opening port A enough for radiators to get hot.

How should it be wired so that no power gets to the valve when only hw called yet wired as instructions and diagrams say?

thanks to anyone who can help

 

[Gas2Air]

If you haven't messed with the wiring then it's the valve passing, either stuck in mid position or not fully closed.

HW Only 240v goes to common on cyl stat, if calling then down to pump and boiler only.

 

[jpgibbo]

Not took current valve off to see if its passing but what i did was buy a new valve and wired it in additionally as a dummy valve and watched how it functioned and it did exactly as current valve. It fully closes ch port when no power to it, it fully covers hw port when just ch called and it sits in middle when both called.

the wiring as it is is how you say, the live when hw called is at common and then feeds from 1 to pump and boiler live but on the drawings for a honeywell mid position valve and also the y plan circuit diagrams on internet the orange wire from the valve is also connected to wire coming from no 1 on cylinder stat so its always going to have a live feed to it when hw called and temp not reached.

sorry i can't upload drawings an referring to but if you google y plan wiring there are plenty and also google honeywell mid position valve the wiring comes up to.

thanks for reply

 

[matt1e]

Don't worry about it
The orange wire is a feed from the valve not to it
Although the orange wire will be live when the hotwater is calling, this will have no impact on the valves motoring mechanism

Matt

 

[Gas2Air]

I understand what you mean. The drawing will give a tee like junction, it will not power the orange back to the valve.

What valve is it?

 

[jpgibbo]

thanks its a honeywell mid position v4073a

whilst watching the dummy valve i had wired into same connections as plumped valve i could see the ball moving from port to port and locating securely to block off hw but not ch. when mains to boiler switched off the ball then secured fully to shut off ch. this to me rules out the valve being faulty as the new dummy valve is behaving in the same way? i am wondering what signal is holding it off from fully blocking off port.

i have also tested for voltage at certain points with just hw selected and it concerns me. There is 240v on my room thermostat, the side connected to white wire from valve. to me this is wrong

 

[MANDATE]

power to operate boiler/pump goes through cyinder stat when HW is is selected on it own or together with CH.
When CH is selected on its own, power comes from valves orange wire and it has to be connected to the same wire from the cylinder stat to fire boiler
So you're right that with HW only it makes the orange wire 'live'.
Inside the actuator 1 of the micro switches is fed by the white wire, which is fed from the room stat.
This micro switch has two output terminals One goes a small PCB to hold valve in mid position, but when valve is moving towards CH only the switch is triggered and power diverted from the PCB to the orange wire.
So with HW only, the orange wire is live, but it only goes back to the open contacts of the micro switch.(unless the micro switch is faulty)

 

[jpgibbo]

thanks for that reply very helpful.

my only concern is the current valve behaving this way and also a brand new valve wired in as a dummy also having a faulty micro switch?

 

[Gas2Air]

Stop naffing about, fit the valve, wire as per and it'll be fine.

 

[MANDATE]

If the micro switch mentioned was stuck in closed position the reverse feed would go back along white wire to room stat.

 

[jpgibbo]

ha i would have fitted the valve but the fact its acting exactly the same points to it being something else, asked the question thinking maybe the wiring or something could be doing this. thanks anyway for help