Room stat overrides the programmer

[Colabear]

Hi guys, I was wondering if you can help me, my wall mounted room thermostat has started to override the main timer/programming box which is a British gas dual channel up2.


Even with the programmer showing off or in between the timed settings the heating will come on if the room stat is above actual temp. The stat clicks at about the correct temp.


So basically my central heating is controlled by the stat regardless of the programmer.??


The hot water kicks in as it should and the mixer valve seems to switch correctly through the 3 positions W M H.


Why does my CH system ignore the box and run off the stat??


Any help very much appreciated as 2 plumbers have failed to return my call after a fortnight

 

[ambrosia]

I'm guessing this is a historical problem, sounds like a wiring fault

fixing a wiring fault is a daunting task for the uninitiated i'm afraid

 

[Colabear]

It was all fine until Tuesday when an engineer shut down the system to fit a new water pump, didn't physically touch the stat or programmer only switched off the supply to it. It's like there is a permanent live going to the stat. Think it's the programmer gone duff

 

[PlumbBobBob]

get that engineer back to fix it

 

[0304Driver]

We would need more info to give a correct answer, it could be a wiring fault or it could be a fault with the timer, what sort of thermostat is it? Would not be the first time that a prog stat was fitted at a later date that overrides the timer!
I am not sure if I am allowed to give advice on here re voltage checks on the stat etc to help find the fault.

 

[Chalked]

The thermostat is working correctly, its the programmer that is at fault. What model is it?

 

[0304Driver]

Strange, when I answered your post about the pump change was not visable. Most prob the timer faulty, have had the same thing happen to them after turning the power off, but can be proved by testing for voltage at the room stat.

 

[SafeGasInstall]

Or it could be the motorise valve

 

[Nostrum]

Is it a grundfos ups2 pump that's been fitted?

there has been some reported issues with these, they draw to much current on startup which melts the contacts in the timers causing them to stay on permanently. If this is the case the pump requires a a suppressor lead fitted to prevent this and the clock will be goosed.

sounds very probably in this case.

 

[Orry Clayton]

The engineer who changed pump has rewired it wrong, in wiring-centre. Should be easy to sort for any competent engineer. Fault is in wiring centre, either a stray wire, or in wrong connection.

I would recommend you isolate the power supply to the heating system until this is fixed, poor wiring can lead to electrical fires, or damage to appliances.