Glow-worm Fuelsaver MKII - Replacing thermostat

[tomton]

Hi,

standard open vented system with 2 zone valves
boiler: Glow-worm Fuelsaver MKII

About 2hrs ago boiler tried to fire up but instead of one click there was a few short ones and it didn't fire up

Since then I've spent time trying to work out what's wrong and I'm 90% sure its the thermostat because it doesn't pass 24V from transformer to the gas valve. Now if I play with thermostat knob the boiler fires up but not every time.

I have found a replacement HERE but I don't know can I install it myself because of the copper wired temperature sensor that I presume goes somewhere into heat exchanger. Can I use the old one and just connect it to new thermostat?

If not can I try to recondition relay that's causing problem?

Any advice or suggestions are more than welcome as it looks like cold night and day tomorrow

 

[gasacs]

You can not legally change the stat yourself as it is a safety device you need an RGI.

 

[tomton]

I won't be taking chances.

any idea how much should it cost?

boiler seems to be working fine now but I don't want to be left without heat on Christmas Eve so it's probably to replace it now.

 

[gasacs]

Cost of part then no more than an hours labour

Although I can not speak for other RGI's I would always want to attend to diagnose the fault myself first.