Y-plan wiring issues

[mackandmutley]

i seem to be having intermittent heating at the moment

I have got home, house is warm, radiators warm-ish, and controller telling me heating is on.

However, boiler (Glowworm) is displaying 39'c instead of usual 70'c when on. Have traced wiring as follows:-

CH ON at controller -240v
Pin 1 at Room Stat - 240v
Pin 3 at Room Stat - 240v
White wire at 3 port valve - 240v
Orange wire at 3 port valve (tested in isolation) - 148v

Any ideas?

 

[seco services]

What reading have you on the grey wire ?

 

[D_Hailsham]

However, boiler (Glowworm) is displaying 39'c instead of usual 70'c when on. Have traced wiring as follows:-

CH ON at controller -240v
Pin 1 at Room Stat - 240v
Pin 3 at Room Stat - 240v
White wire at 3 port valve - 240v
Orange wire at 3 port valve (tested in isolation) - 148v

Those voltages are OK if you had CH ON and HW ON. But if only CH was ON, the orange wire should have 240V and the grey wire should also have 240V.

 

[mackandmutley]

Grey wire I have 75v with red wire still removed from main wiring

 

[MANDATE]

My guess is that the motor/quadrant/valve moves to mid position, so you get HW and CH together. This only lasts till the HW becomes satisfied, when the motor/quadrant /valve is then supposed to move to CH only position. During this movement it is also supposed to activate a micro switch will make the orange wire live and supply power to light.
My guess is that either (a) the motor/quadrant/valve is not going beyond mid position or (b) It is going to CH as it should but is not making the orange wire live.
(a) can be due to fault in wiring. eg no power on the grey wire to drive motor from mid point onwards.
(a) can also be due to faulty micro switch No 1
(a) can also be due stiff spindle on valve
(b) will be due to faulty micro switch No2.
First try to establish if valve moves to CH position or not

 

[mackandmutley]

How do I check it moves to CH position, sorry if thats a stupid question

 

[MANDATE]

How do I check it moves to CH position, sorry if thats a stupid question

Starting with both HW and CH off, put HW on.(with cyldr.stat higher than normal to ensure demand
If valve not already at HW, valve will unwind due to return spring to the rest position (HW)
Now best to get someone to put CH on (with room stat higher than normal to ensure demand) while you listen for motor and valve movement. The power from room stat can only drive the valve to mid point.
Now get helper to turn HW off (or lower cylinder stat setting) This makes the grey wire live and again listen for motor and valve movement.

You can do the above with the actuator head removed from the spindle and observe the underside.
There are two conditions where the grey wire needs to 230v to drive motor.
(a) when HW is on and has been satisfied. power across cylinder stat is diverted to grey wire.
Also (b) when HW is not switched on. power comes direct from the programmer HW OFF terminal to the grey.
If the grey's not live the valve cannot travel beyond mid point.