Having looked at the wiring diagram, I see a conductor must be run from the L2 of the cylinder stat (presumably the 'I'm hot' position) to the HW off of the programmer and the grey wire of the 3port valve........why is this?
Sundial Y wiring question
- Thread starter DIYedboy
- Start date
D
davebgas
to hold the valve in mid position giving 'break voltage' on the grey wire.
Also to ensure valve motors across for heating only. The grey wire MUST also be run back to the programmer HW off connection NOT just to the cylinder stat satisfied.
Also to ensure valve motors across for heating only. The grey wire MUST also be run back to the programmer HW off connection NOT just to the cylinder stat satisfied.
D
davebgas
When you have CH & HW selected on a Y plan, you get a 'back' voltage on the grey wire. Its usually 50-110v. A quirk of the system and wiring within the MV. Perfectly normal though.
When both CH & HW are called the cylinder stat has live on common and terminal 1 which fires the boiler. The room stat has power on the white wire which drives the valve to mid position, where the 1st microswitch diverts power and converts to motor into a magnet, stopping it in mid position (hence break voltage). Because the pump and boiler are already firing then both HW & CH are served.
If HW is satisfied either by cylinder stat or prog, the valve will then motor to heating only
When both CH & HW are called the cylinder stat has live on common and terminal 1 which fires the boiler. The room stat has power on the white wire which drives the valve to mid position, where the 1st microswitch diverts power and converts to motor into a magnet, stopping it in mid position (hence break voltage). Because the pump and boiler are already firing then both HW & CH are served.
If HW is satisfied either by cylinder stat or prog, the valve will then motor to heating only
D
davebgas
Mid position situation described above - Sundial Y Plan
diverter valve hasn't got a grey wire.
No it doesn't.
With a diverter valve you can only have hot water or heating but never both at the same time.
D
davebgas
W plan.... usually hot water priority
D
davebgas
No it doesn't Dan
Just a brown, blue and earth.
It springs return to port B and powers open to port A.
i thought he was gods gift to heating engineers
even the bloke at asda knew that
The purpose of the 'grey' wire is to supply power to drive the motor from mid position on to the CH only position, this is required when HW is either satisfied or it's off.
When HW only is selected the valve stays or drops back to its rest position and the valves electrics play no active role.
If both HW and CH are selected and neither of them are satisfied, the valve moves to mid position and is held there. It does this because in addition to 240v being applied through micoswitch No1, it also applies 240v through microswitch No2 and feeds a pcb. This pcb produces a dc rectified voltage, which is fed to the motor at the same time as the 240v.
So 1st stage motor driven to mid point by 240v (white)
Option (a) If 'grey' is live it takes over when microswitch is triggered, which drops the 'white' and valve continues. or
Option(b) If 'grey' is not live when the white is dropped, then it leaves the rectified voltage to hold valve in mid position.
If the grey wire was removed, the valve would still go to and stay in the midposition.
When there is no 240v being supplied to the grey from either stat or programmer, there is a back voltage from the rectified voltage that feeds back through the microswitch to the grey.
When HW only is selected the valve stays or drops back to its rest position and the valves electrics play no active role.
If both HW and CH are selected and neither of them are satisfied, the valve moves to mid position and is held there. It does this because in addition to 240v being applied through micoswitch No1, it also applies 240v through microswitch No2 and feeds a pcb. This pcb produces a dc rectified voltage, which is fed to the motor at the same time as the 240v.
So 1st stage motor driven to mid point by 240v (white)
Option (a) If 'grey' is live it takes over when microswitch is triggered, which drops the 'white' and valve continues. or
Option(b) If 'grey' is not live when the white is dropped, then it leaves the rectified voltage to hold valve in mid position.
If the grey wire was removed, the valve would still go to and stay in the midposition.
When there is no 240v being supplied to the grey from either stat or programmer, there is a back voltage from the rectified voltage that feeds back through the microswitch to the grey.
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