Heating Not Switching off with room thermostat

[kas]

Hi, Need some help.
My CH/HW system has a problem. Everything works fine except for one thing, the heating is not being controlled by the hallway room thermostat, it is permanently on if the programmer is set to heating 'On'. Obviously if the thermostat is turned down below the ambient temperature than the stat should trigger the CH to turn off and vice versa if it is to cool the heating should fire back up, as it has always done since I moved into the house. But alas my heating stays on regardless of stat temperature.
This came to light last night when I put the heating 'on' and after about an hour the heat was obviously above what it should have been, i twisted the stat up and down a few times but nothing cut the boiler off.
I did change the Drayton Ma1 3 port motorised valve during the summer as it was faulty (when hot water selected the rads were partially heating up so valve needed changing). Could the new valve be faulty in some way?
When I turn the room stat slowly around it still clicks at the point the boiler should come on/off, but has no effect, could the thermostat still be faulty even though it 'clicks'.
As I say there are no other faults apart from the heating not been regulated by the room thermostat, it is just either on or off via the programmer.
Please help, what are the chances it is linked to the 'new' valve i installed and being defective. ps I have checked and double checked all the wiring in the airing cupboard with no solution to the problem.
Thanks in advance. kas

 

[Gasmk1]

yes thermostat could be faulty even if it clicks also the valve you changed may not have been wired correctly, gte the guy back who changed it

 

[kas]

Hi, Thanks for the reply. I actually did the valve change myself. I just re-wired it up as it had been previously (took photo's etc etc). I have double checked the wiring and it all seems fine. Any ideas how I can 'test' the room thermostat? It is a Drayton turn wheel style (not digital).

 

[kas]

 

[kas]

Picture of the wiring. Bit of a mess I know but that's how its always been. Can anyone see a wiring problem?

 

[joni os]

Identify wiring from room stat at wiring centre. Disconnect return wire and check if wire only becomes live when stat calls for heat. If so your stat is working correctly. Down load wiring plan to match your set up and rewire accordingly. Finally if problem persists disconnect heating call at wiring centre, leaving call for DHW and if rads still get hot and 3 port valve is correctly orientated then valve is probably stuck.

 

[kas]

Unfortunately I do not have the necessary equipment to test wiring. I'm thinking the 2 likely culprits would be either the thermostat or the motorised valve. Would somewhere like Screwfix let me buy both and return if not faulty or not required. The valve can be checked quickly as the body seperates from the copper valve and likewise with the room stat. Are there any other possible problem areas?

 

[Gasmk1]

is the white wire from the valve if so most systems dont use the white wire was it definatley connected,

 

[kas]

Hi, Have got it sorted. I doubled checked all the wiring again and found that the 'white' wire from the new valve was in the wrong place, moved to correct place and now communicating with the thermostat again. Phew, just glad it's sorted. Thanks for the help !

 

[kas]

Had to move white wire one place to the left (where it was originally) dont know how I messed that up. Gasmk1 you were on the right lines. Thanks

 

[kas]

Any idea on best way of tidying that connector block up, or housing it in something more suitable so it is not disturbed.

 

[rpm]

Any idea on best way of tidying that connector block up, or housing it in something more suitable so it is not disturbed.

Maplin sell boxes of various sizes.

 

[kas]

Ok, thanks will take a look. Probably a job for another day as just glad it's sorted. Thanks again.

 

[leesparkykent]

Ok, thanks will take a look. Probably a job for another day as just glad it's sorted. Thanks again.

https://www.amazon.co.uk/Ashley-J701-Electrical-Junction-Box/dp/B005EQL9NW

easiest option would be to screw a j701 jb to the wall, cut out the required amount of entries and place the wiring/ connector blocks inside. This way you don't have to disconnect anything and you can give the terminations the required strain relief as the j701 has tabs for cable ties.