No DHW and CH together.

11 Nov 2011
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United Kingdom
I am unable to get DHW and CH on at the same time, when CH is on switching DHW on cuts power to boiler. When DHW is on, switching on CH will not come on (no led on, on controller)
System: Potterton Kingfisher Boiler,, Drayton SM2 Controller,, Honeywell V40A mid position valve. I believe system is Y type, pumped system.

I have checked the link on rear of Drayton SM2 Controller it is in P (pumped)
All connections in Honeywell junction box are secure.

I moved in 2 months ago it has never worked since moving in.

I found a spare valve motor in a bag under hot water tank so it has been worked/fiddled with before.
Any help greatly appreciated. :D
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Probably wrongly wired!

Tedious to check but it has to be done!

Because the SM2 Controller LEDs aren't coming on as expected I think I'd want to check the signals coming out of that unit before going any further. It would require a multimeter for that though.
Turn off the power
Remove the SM2 controller from the backplate
Install a temporary wire link between L, 3 and 4.
Switch on (without the controller fitted)

If the hot water and heating now work, the controller needs to be replaced.
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Thanks for help so far,
I linked 3 and 4 on controller as advised, no difference.
How much does the mid pos type valve rotate with the head assy removed? I checked out if it was siezed, it is free but only moves about 40 degrees, didnt want to force it any more without confirming how much movement there should be.
I have tried checking out if wiring is correct but is diffucult without correct diagram.
One thing I noticed when both selected on both HW and Ch led's come but dim, switching off one system results in remaining led becoming bright and boiler and pump firing up, the mid pos valve doesnt move it remains in semi mid pos with micro switches not contacted.
When I switch of power completely the spring drives valve fully one way.
Do you reckon the valve or actuator or both are at fault?
Can any tell me with actuating head removed from a Honeywell mid pos valve, how many degrees approx will I be able to manually turn the valve drive shaft using pliers?
10 oclock dhw, 12oclock mid, 2 oclock heat, roughly. should be able to turn easily with pliers. sounds like it is wired wrong though? does motor operate at all?

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