Thermostat issue

[uyevuye]

Hi All.
We have Greenstar RI boiler for pressurized system. Our thermostat is British Gas RS1.
Yesterday I have noticed boiler is constantly on. Today I have reduced the thermostat to lowest to test it. Despite thermostat is on lowest, boiler is still on.
Do you think issue is the boiler thermostat or British Gas RS1? I am a keen DIYer. Do you think it will be an easy task for me to replace the thermostat - after turning all electricity off? Which thermostat do you recommend?
Thanks

 

[RandomGrinch]

Do you think issue is the boiler thermostat or British Gas RS1?

Remove the RS1 from its backplate (avoid touching the live contacts!).
Does the C/H turn off?

 

[terryplumb]

Possibly a motorised valve fault. If you switch off the programmer does boiler continue to run ?

 

[uyevuye]

When I turn off the programmer (British Gas Model UP1) boiler turns off. So I think issue is isolated to thermostat.

Also if the issue is the thermostat, can I take the front panel off and replace with front panel from Drayton RTS1 1-Channel Wired Room Thermostat , without any changes on the back connector panel?

 

[RandomGrinch]

Also if the issue is the thermostat, can I take the front panel off and replace with front panel from Drayton RTS1 1-Channel Wired Room Thermostat , without any changes on the back connector panel?

Yes it would be a straight swap.
But as earlier...

Remove the RS1 from its backplate (avoid touching the live contacts!).
Does the C/H turn off?

To check that it really is the thermostat!

 

[uyevuye]

When I remove the RS1 from the back plate, C/H turns off.

So straight replacement for RTS1 then. Correct?

 

[RandomGrinch]

When I remove the RS1 from the back plate, C/H turns off.

So straight replacement for RTS1 then. Correct?

Yes.

... Or for a temporary solution, you could try giving the RS1 a couple of sharp taps with the handle of a screwdriver - it may free up a stuck contact, but it will definitely help to relieve any frustration!

 

[uyevuye]

Great. Thanks for the help.

Little tap always might work. Even Han Solo gives a tap to Millennium Falcon.