No Central Heating, Hot Water working

[gsdaheley]

Hi,

Here's my issue. HW is functioning as usual. CH however is not coming on. I have ensured the room thermostat is turned to max, and set the programmer to on.

The only way I have managed to get radiators warm is to move the lever on the mid position valve to manual and switch on hot water.

What I have tried so far:
• Replaced the Synchromotor on the valve (It's a Tower VAL322MP)
• Replaced the thermostat (this was because it was worn and stiff so replaced as matter of course. It's a Honeywell T6360)

I am certain the motor is functioning because I connected the white wire from the mid position valve to live, and it moved the lever over to the manual side and the boiler fired up.

However when I put wires back as they were, theres nothing.

Would appreciate some guidance!!

It is a partly pumped system (hot water side), pressurised system (I'm assuming because we have a tap to fill boiler up and a pressure gauge we keep eye on, on the boiler).

If there's any more info or pictures you might need I'm willing to upload these.

 

[stardanny]

It's possible that the micro switch or PCB inside motorised valve head might be broken/faulty?

Can you test the stat to see if the live out switch on when turn up and switch off when turned down?

Daniel.

 

[gsdaheley]

Thanks for the reply.

It's possible the pcb or switched have gone as the unit is about 18months old. But connecting the white wire to live solved the problem. Motor whirred up and moved the motorised valve and the boiler began warming the rads.

There is an issue with the stat also. It's slightly different from the one I had in before and had different terminals. I have made a best guess at wiring. I've attached pictures of what I've done and the wiring diagram on the new stat:

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• gsdaheley
• 24 Apr 2014
• 1

and heres the junction box

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• gsdaheley
• 24 Apr 2014
• 1

The wires from the top left grey cable is from the room stat. Brown going to first block used (together with one yellow wire- i think from the programmer) and the black going to the next block along where it is joined on the opposite side with the white wire.

Hope this helps

 

[stardanny]

On the stat, terminal 3, where's the wire? Seem missing.

How many wires are there in cable to stat?

Daniel.

 

[gsdaheley]

The wire includes 3 wires and an earth. But the old stat only had the two I have wired up so didnt use the 3rd (grey).

That's next step?

 

[Whitespirit66]

As above, looks like your switched live is missing from terminal 3. Other end of this wire should connect to white wire on motorised valve.

 

[gsdaheley]

OK, so to be clear, switched live (term 3 on stat) should be leading to the junction box and connecting to white wire? or common neutral?

 

[stardanny]

Also, is two cables on top right for programmer?

The black wire on the connector block in junction box, the one with white wire, take that out and swap with grey wire on same cable, reconnect black wire back where grey wire was and reconnect grey wire back where black wire was.

Then, you see the grey wire on stat, connect that to terminal 3 on stat.

Hope you understand

Daniel.

Edited: correct colour.

 

[Whitespirit66]

White wire.

 

[gsdaheley]

Ok thanks. I think I understood (I went slow and double checked!)

Here's what I have at the moment:

Untitled

• gsdaheley
• 24 Apr 2014
• 1

Untitled

• gsdaheley
• 24 Apr 2014
• 1

And yes the two white cable on top right are going to programmer.

 

[gsdaheley]

So I have a mains voltage tester. When I apply it to terminal 1 on room stat and the stat is set to a low temp, it reads 12v, when turning up to max, it goes to nothing.

There is no change on the other terminals as I turn the stat.

Hope that helps?

 

[stardanny]

Where did you test on?

Daniel

 

[gsdaheley]

i tested on the terminals of the room stat using a screwdriver tester which shows voltage levels

 

[stardanny]

The photo shown is correct now, the heating should work.

Forget the screwdriver tester, it's no good

Daniel.

 

[gsdaheley]

ok. i dont have a multimeter.

heating isnt working...