Boiler not firing for CH - duff roomstat? Theben Ramses 811

[Yakkity]

Hi

I am having issues with getting my ancient (Gloworm Fuelsaver F) conventional boiler to fire up for central heating. When the room stat - (a Theben Ramses 811 top1) has been turned up and heard the audible 'click' the boiler does nothing. DHW is running fine and the tank thermostat fires the boiler fine.

I initially thought I had a faulty programmer (an original Drayton Switchmaster 805) which I have now replaced with a Drayton LP241. The programmer seems to work fine, I can turn HW heating on/off via the programmer fine.

The room stat has a 2-wires connected so I'm hoping to find a cheap compatible replacement.

The manual for the current room stat is
http://www.theben.de/var/theben/sto...instructions_RAMSES811top_RAMSES812top_en.PDF

Any help would be very much appreciated. Is it possible to override the room stat and force CH 'on'?

Cheers

 

[Yakkity]

As an aside, I noticed that when the boiler is on for HW heating the radiators warm up - is this the norm?

 

[denso13]

Connect both wires together at the room stat. This should mean the CH will be on constantly and will confirm if the stat is at fault.

 

[Yakkity]

Many thanks for the quick reply

Ok, done that - still nothing from the boiler...

 

[twgas]

Motorised valve looks to be most likely suspect.

 

[denso13]

Kinda rules out the room stat. Do you have any motorised valves?

 

[Yakkity]

Hi, yes there is a motorised valve in the airing cupboard. The lever seems to be in the 'auto' position. It moves very freely up/down with no audible click or any change from the boiler end.


Here's a (bad) photo :

Untitled

• Yakkity
• 2 Nov 2014
• 1

 

[Yakkity]

Thanks chaps, I performed the CH only test as per

//www.diynot.com/forums/plumbing/boiler-central-heating-faqs.175736/page-2

and got nothing so it would seem certain to be the mechanical valve?