Mar 11, 2010
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Hi all,

got a combi boiler with volt free switching for the central heating all working fine, I put a conservatory up and put underfloor heating in , I asked the plumber to put a value on the UFH pipe and the CH Pipe so I could control them separately , from a salas wireless programmable stat, so basically a s plan. I've come to wire it but having problem as the combi is volt free and I can't see how to open the valves without putting 230v to the boiler sw. Any ideas?
Cheers
grand
 
Wont the valves be opened by the stats controller and the paralleled micro switches signal the boiler with its own go signal of whatever voltage?
 
Wire it up as if its a standard 2 port system. You will need a 240v supply thru your stat to open the valve and the stat terminals on the boiler should go thro the valves switch, which would be volt free. It would be the same for both valves.
 
Wire the 240volt side to work the motor side of the valve, feed this from your wireless stat control box then wire the volt free contacts of the boiler onto grey and orange of the valve
 
I've done a lot of heating systems and you do have a bit of an awkward one there. Where is the valve in relation to the boiler? Close by?

Guys this is quite simple. The volt free contacts aren't in the boiler but in the external controls. There's a voltage of some sort coming out of the boiler hence the link you have to remove when fitting the external control.
wire the motor of the valve through a 240v supply via the room stat, blue neutral grey being switched feed from stat.
the grey wire in the valve connects to one of the external control connections in the boiler and the other connection is connected to the orange. This means that the volt fee contacts are in the valve across the switch. They are volt free when no voltage is connected to them but the boiler sends a voltage out of possibly 24v.
the second valve would be exactly the same connections and you can double up the orange and grey cables of both valves as this doesn't affect the switching of the valves independently
i hope this helps, you could draw the wiring out first to follow the switching and then you will probably have the light bulb moment good luck
 
Guys this is quite simple. The volt free contacts aren't in the boiler but in the external controls. There's a voltage of some sort coming out of the boiler hence the link you have to remove when fitting the external control.
wire the motor of the valve through a 240v supply via the room stat, blue neutral grey being switched feed from stat.
the grey wire in the valve connects to one of the external control connections in the boiler and the other connection is connected to the orange. This means that the volt fee contacts are in the valve across the switch. They are volt free when no voltage is connected to them but the boiler sends a voltage out of possibly 24v.
the second valve would be exactly the same connections and you can double up the orange and grey cables of both valves as this doesn't affect the switching of the valves independently
i hope this helps, you could draw the wiring out first to follow the switching and then you will probably have the light bulb moment good luck

youve lost me with your idea there.
 
youve lost me with your idea there.

Try this
from switch spur to a room stat, from room stat to brown and blue of valve
connect grey and orange of valve to external controls terminals in boiler after removing the link
230 volts from the spur via room stat turns valve motor which in turn makes the micro switch close in the valve
the micro switch is connected to the external controls terminals in the boiler.
and bang the boiler fires up (not literally bang)
 
But if both valves are in the open position, voltage on the orange and you shut one valve it won't shut until you lose voltage to the other
 
So your connecting the switch wires of the valves together?

Nope the micro switch wires grey and orange are separately connected to each external control terminals in the boiler.
image that the first terminal in the boiler is a feed to a light switch (grey) and the 2nd terminal is connected to the switch line (orange) coming back from the switch
 
But if both valves are in the open position, voltage on the orange and you shut one valve it won't shut until you lose voltage to the other
You have two separate voltage sources, one from the switch spur and one from the boiler completely separate so that it doesn't matter what the valves do it will not affect each other
 
Jesus, I'm pleased you get It redvanman, the grey and the orange on a two port are separate to the 240v side hence giving you the boiler no volt side. Why do electricians find c heating so complicated!
 
Hallelujah some one else can do c/heating you would be amazed how many electricians I come across who don't understand the wiring, it's really only switching

Boydy, my patience is this long on site hence I normally work alone GRR
 
So redvanman if both valves are open hence both putting voltage to the ignition/fan. Are you saying if one of the stats stop calling it will shut even if the voltage is present from the other stat surely it will be held open back feeding from the fan and ignition side of the boiler. Have you looked at the schematic for the jaguar boiler?
 
no it would work the same as normal s plan ie when stat stops calling for heat the valve would shut opening the contact between grey and orange its the brown and neutral wires on the valve that makes it open and close
 
It doesn't matter if they are spring return or not the valve motor is fed from one supply and the micro switches are fed from a different supply so no back feed.
i feel sorry for grandfortune he's probably ripped the boiler of the wall my now
 
But if they are both igniting the same boiler in the end they will meet at the ignition pcb. So no matter where the supply originates if they meet at the end they will affect each other. There only one way to find out, he should do it and tell us if it works.
 
how does a 230v s plan work then ????????? as both valves still connect to the same terminal in the boiler
 
But if they are both igniting the same boiler in the end they will meet at the ignition pcb. So no matter where the supply originates if they meet at the end they will affect each other. There only one way to find out, he should do it and tell us if it works.

Some one pass me a gun:29:
 
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Jesus, I'm pleased you get It redvanman, the grey and the orange on a two port are separate to the 240v side hence giving you the boiler no volt side. Why do electricians find c heating so complicated!


we probably find it complicated cus we alwas pump 230v down, i understand what Radvanman is saying just never wired it like that.i also understood what onions was saying about the switches as both would be open if they were put together in the boiler connections, unill i drew it out, onoins the 230v to the stat opens the value so i doesnt matter if they are connected together if the stat isnt calling it wont send the 230 to the motor of the valve, am i right there??

Thanks for the reply's guys, 1000's of S and Y and S+plans & air source haeting done never had to wire a boiler like this before, probably cus im trying to get it to work with a Combi
 
How can it back feed when 1 stat does one motor and another stat does other the motor. The only parts that are linked together is the no volt contacts to tell the boiler to fire up
 
Which in turn control the 230v side of the fan and ignition pcbs . As I said only1 way to find out is to connect up.
 
So the boiler generates its own low volt signal, which is returned when the micro switch is operated. Is the micro switch operated physically when the valve motor turns, by a cam. Therefore two voltage system but completely separate. Only mechanically connected.
 
jesus christ power up a 2 way valve switch live (brown) without the permanent live connected (grey) the valve will open and close as power connected and disconnected via stat, the orange will allow through whatever voltage is connected to the grey (usually 230) or in this case the volt free supply from boiler
 
jesus christ power up a 2 way valve switch live (brown) without the permanent live connected (grey) the valve will open and close as power connected and disconnected via stat, the orange will allow through whatever voltage is connected to the grey (usually 230) or in this case the volt free supply from boiler
So what is switching the boiler and you just said the grey was disconnected so the orange won't be letting anything through
 

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Valves on a combi volt free
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