Help on central heating motorised valve wiring

[Stevehobbs]

Help got a Y type system, long story but plumber just changed motorised valve complete with motor so all new. Unfortunately he doesn’t do electrics. I have looked at the wiring diagram and checked everything through and found that the HW off wire did not connect to anything nor could I find it in the airing cupboard and hence the grey wire to motorised valve and terminal 2 on the cylinder stat were not energised. I connected both these up to HW off on the programmer using a temporary wire and was hopeful , I have checked and double checked all other wiring and all seems well. However……on HW only I am getting power on orange to fire boiler but at same time the white powers up sending a feed to the room stat which to me sounds wrong. Any ideas anyone please, I am thinking the new switching within the motorised valve maybe faulty ? It’s at a rental so can’t check tonight but if valve not set to auto would this cause this ?
on a side issue I have a terminal block with a red and yellow wire seemingly redundant that power up when heating turned on but can’t see that they are relevant to anything or connect up to anything , just curious what these may be or may have been?
Any help please ?….. Valve is V4073A Honeywell

 

[terryplumb]

If you disconnect the white wire from the terminal block that it is in currently ,and place it in an unused terminal block on its own ,then measure the voltage from it to earth,what is the voltage when programmer is calling for hot water only ?

 

[Stevehobbs]

Thanks Terry cannot test that until tomorrow, I know the white goes down to room stat call side. What are you thinking ?

 

[terryplumb]

If the white wire from the MPV ,when disconnected from any other wire ,is reading 230/240v the voltage has to originate from the MPV doesn't it.

 

[Stevehobbs]

If you disconnect the white wire from the terminal block that it is in currently ,and place it in an unused terminal block on its own ,then measure the voltage from it to earth,what is the voltage when programmer is calling for hot water only ?

Thanks Terry it’s at a rental so cannot check until tomorrow. I have continuity tested the white and it goes to call side of room stat. The heating on its own seems to be fine. What are you thinking ? Would valve being in manual which I need to check tomorrow have any effect ?

 

[Stevehobbs]

If the white wire from the MPV ,when disconnected from any other wire ,is reading 230/240v the voltage has to originate from the MPV doesn't it.

Yes that’s what I am thinking so that being the case does that not indicate that the MPV switching is not functioning correctly. If so is there anything that would cause that ? I cannot check tonight but could valve be connected incorrectly ie HW to heating and vice versa or valve being in manual ?

 

[terryplumb]

You stated " the white powers up", what exactly do you mean ?
The manual position only moves the mechanical part of the MPV to a central position ( open to both ports) it does nowt electrically .

 

[Stevehobbs]

You stated " the white powers up", what exactly do you mean ?
The manual position only moves the mechanical part of the MPV to a central position ( open to both ports) it does nowt electrically .

With hot water only I get power to common of cylinder stat, as soon as the stat calls to heat up on terminal 1 the orange receives 240v to fire the boiler but simultaneously so does the white wire which goes to the call side of the room stat . Hope that makes sense but the heating only all works fine with roomstat powering white an firing boiler as it should. I just don’t think when 240v is supplied on heating on orange the white shouldn’t get anything and think it may be motor head but it’s new and all wiring looks good . Any ideas ?.

 

[terryplumb]

Just to clarify...are you saying when the programmer is set only for domestic hot water , the white wire from the MPV has 230/240 volts ?
The white ,and grey wires are inputs (supply voltage to the valve) ,therefore if the white wire is isolated from any other and it's reading 230/240 volts ,whilst the programmer is only calling for domestic hot water, that would indicate something's amiss within the actuator head of the MPV.
Having said that ,I personally have not ever came across such a fault.

 

[Deleted member 267285]

Help got a Y type system, long story but plumber just changed motorised valve complete with motor so all new. Unfortunately he doesn’t do electrics.

I don’t get why he’s doing half jobs then? Are you able to post photos of the wiring? Are you the landlord then?

 

[Stevehobbs]

Just to clarify...are you saying when the programmer is set only for domestic hot water , the white wire from the MPV has 230/240 volts ?
The white ,and grey wires are inputs (supply voltage to the valve) ,therefore if the white wire is isolated from any other and it's reading 230/240 volts ,whilst the programmer is only calling for domestic hot water, that would indicate something's amiss within the actuator head of the MPV.
Having said that ,I personally have not ever came across such a fault.

Yes that’s exactly what’s happening with hot water on I seem to be getting output of 240v on orange and white which is stumping me, all circuitry looks spot on White as an input from room stat is all functioning great but I get an output on it on hot water only along with orange. Am thinking motor head although new must be faulty….?

 

[Stevehobbs]

I don’t get why he’s doing half jobs then? Are you able to post photos of the wiring? Are you the landlord then?

Hi Chris I am the landlord, plumber now on holiday but he doesn’t do electrics ….. He fitted new boiler but doesn’t have HW off wire connected which I need to run a wire tomorrow. A temp wire got every thing I needed only this bizarre output on white that I don’t understand. I am thinking he has changed valve and not head.

 

[ericmark]

With the wiring connected you can get some odd readings depending on the meter you are using, White is from roomstat powered to move valve, grey comes from cylinder stat and is powered when hot water is NOT to be heated, and causes the valve when grey is powered to motor all the way across.

 

[Stevehobbs]

View attachment 280336 With the wiring connected you can get some odd readings depending on the meter you are using, White is from roomstat powered to move valve, grey comes from cylinder stat and is powered when hot water is NOT to be heated, and causes the valve when grey is powered to motor all the way across.

Hi it seems when cylinder stat calls and sends 240v on orange SW2 in diagram is in wrong position sending 240v also on white and I don’t think I can repair that. Does that make sense ?

 

[terryplumb]

If you disconnect the orange wire at the wiring centre ( isolate it in an insulated terminal block) and test voltage on white wire ,if it still reads 230/240 volts with programmer set only for domestic hot water ,the issue is not within the actuator.