How to check call for Central heating

[robval]

How can I check if the call for central heating is working?

When the control panel is set to CH the mid valve doesn't move there.

I changed the syncro motor but still no joy.

Though if I manually move the mid position valve from HW to mid - it automatically continues through to CH and the CH comes on.

I am wondering if the small Circuit board in the mid position valve is toast - can that be swapped out?

But just want to check that is the case by proving that the call for CH is reaching the mid-valve just not making it move.

Wanted to avoid the wet side!

Cheers

 

[EliteHeat]

Check voltage to white wire on 3PV, if present verify orange 0V. Otherwise, if white not 230V track back to room stat and finally programmer.

The answer is seconds away.

 

[gavinda]

I changed the syncro motor but still no joy.

Though if I manually move the mid position valve from HW to mid - it automatically continues through to CH and the CH comes on.

I am wondering if the small Circuit board in the mid position valve is toast - can that be swapped out?


Cheers

from this despcription and without some voltage readings id be prone to agree with you. sadly no, you will have to replace at least the head... what valve is it?

 

[robval]

Have 230v on white wire to mid-pos valve when call for heating at thermostat. - Which is good right?
The 2 oranges to the syncro motor:
One has 230V when call for heating but the otherside is always 0V

I have to manually move the 3pv to CH once it gets to mid though - syncro motor seems to take over and move the rest of the way to CH?? Or maybe there is spring loading doing that?

However valve stays at CH with the electricity kept on (even if call for CH off) but 'falls back' to just HW which is the default position spring returns it to if electricty turned off.

I suppose the bit I am not understanding is what is keeping the valve at CH when no call for CH?

Feel I am almost there with the diagnosis just like to understand a bit better.

Thanks for all the help very imformative (and helpful) forum.

 

[matt1e]

the 230v on the grey is keeping it there
from your description the valve is knackered as
230v on white = mid position on its own with out any help

 

[matt1e]

also the reason the valve takes over when you get to mid position is that you are toggling over a micro switch that connects the motor to the grey wire it is the grey that drives the valve to heating only not the white as you may think
matt

 

[MANDATE]

you will have to replace at least the head... what valve is it?

It's to be hoped it's not an old 'drayton'

 

[robval]

'Fraid it is one of the old acl lifestyle. Where the head can't be changed.

Pretty sure it is one of the micro switches that is kaput - are these changeable items - if so where can they be sourced from?

But will probably order a new valve next week - the new style at least has the changable head!

 

[MANDATE]

certainly looks like M/S no 1 culprit.
Power from 'white' is not getting across M/S to motor to drive quadrant to mid point.

are these changable items

well I would say not, but see the thread by 'grindstone'. He mistakenly got a head he could not swap, but did manage to replace the inards with those from new head. (ie The pcb complete with both M/S No 1 & 2).
There are M/S available, but there are loads of styles and types you would need precise details. I do believe though, that they are 'bolt' on as against 'soldered on'

 

[MANDATE]

I believe CPC of Preston stock M/S by the hundred.

 

[BOB D.O.L.E]

i would check the cylinder stat has the brown wire gives power to the boiler and pump when in cental heating mode only.

http://www.octaveblue.co.uk/c_heating/index.htm

check this out.

 

[matt1e]

I would check the cylinder stat has the brown wire gives power to the boiler and pump when in cental heating mode only.

Eh- nothing to do with the problem
1)The cylinder stat may or may not have any brown wires in it
2)the cylinder stat has nothing to do with driving the valve to midway anyway

 

[BOB D.O.L.E]

I would check the cylinder stat has the brown wire gives power to the boiler and pump when in cental heating mode only.

Eh- nothing to do with the problem
1)The cylinder stat may or may not have any brown wires in it
2)the cylinder stat has nothing to do with driving the valve to midway anyway

1) some may not and some may how do you know he has no brown.

2) i never mention that the cylinder stat drives the motor to mid what are you talking about.

if you turn off the room stat and the cylinder stat and then turn on central heating only on the programmer you should have power to the room stat.
then turn on the room stat there should be power going through the white to the 3 port valve the valve should motor over but there still could be no power to pump and boiler , if the off switch on the cylinder stat is not connecting this switch providesw power to the boiler and pump when there is only a calling for central heating


CHANGE THE CYLINDER STAT

 

[matt1e]

to answer your questions bob

1) some may not and some may how do you know he has no brown.

how do you know he has got a brown?
Simple answer I don't and neither do you that's why I wouldn't advise checking it

2) i never mention that the cylinder stat drives the motor to mid what are you talking about.

I never said you did it was robval (the one with the problem) who mentioned

When the control panel is set to CH the mid valve doesn't move there.
Though if I manually move the mid position valve from HW to mid - it automatically continues through to CH and the CH comes on.

ie the problem is the valve won't drive to mid- position

he's A question for you if reading through posts again you still come to this advice

CHANGE THE CYLINDER STAT

please explain why?

 

[MANDATE]

The lever is being used to drive the valve to mid position, once there 'grey' takes over to drive valve to CH position. Boiler lights because there is no problem on M/S No 2. (that is 'white' feeds M/S No 2 and powers the 'orange' to light boiler)
The 240 v power source on the 'white' is not getting through M/S No 1 to drive the motor to mid position.
Seems pretty straight forward to me. Can't see how cylinder stat is involved cause it does not light the boiler in CH only mode.