boiler cuts out after 15-ish mins normal operration

[jonnyf]

Hi there guys and girls.

Am having a problem with my GLow-worm fuelsaver MKII 50B.
It works for about 15 - 30 mins normally before cutting out (stops firing and pilot goes out). usually with a banging noise in the pipes near boiler. has been suggested it might be the Overheat Stat on the water feed pipe but when checking today it seems that the boiler doesn't need to get very hot at all before it cuts out. Then it takes ages before the pilot can be lit again. Very very annoying. Water pump seems to be working okay, is it worth replacing the overheat stat as a first approach?
Any suggestions would be gratefully revieved.
Even just directions to the manual on the web for this model. The glowworm website doesn't seem to believe the fuelsaver 50b exists??????!!

 

[hellomum]

no the overheat stat is working as it should because ya boiler is overheating

 

[jonnyf]

thanks for the reply but you've confused me a bit. is the overheat stat not supposed to stop it overheating?

 

[Botmission]

The pump may be working, but is it circulating the water? An air lock or a restriction/blockage may be the cause. Is there an air release above the boiler? Is there enough water in the system? Do you get heat and hot water?
The overheat stat will trip near boiling point.

 

[jonnyf]

is circulating the water fine, at least I think it is, presumably the radiators wouldn't get hot if it wasn't and they do. And there is enough water in the system. Water looks relatively clean too. there is an air release valve above the boiler that is loose.

Again, thanks for the reply.

jf

 

[Botmission]

Try setting the boiler thermostat to minimum and see what happens.....

 

[jonnyf]

tried that, seems to cut out the same. today was cutting out when not even getting very hot????

 

[Botmission]

Difficult to be any more help from here, I don't think you'll be able to fix it, as it appears to be a fault on the boiler, and only the appropriate people should work on it.

 

[jonnyf]

yep

is what I was thinking. I am getting a qualified plumber round but last 2 I got were rubbish at diagnostics. Just thought someone could give me a clue so I knew what parts to pay for. No refund if they fix a part that was already working.

Thanks everso for your time anyway though

kind regards

jf

 

[gas chap]

Is it a fully pumped system?

 

[jonnyf]

sorry, not sure what that means. think it is a vented system. (has vent on back going to outside world). has the 2 tanks in the loft. 1 big 1 small and water storage tank in airing cupboard.

 

[gas chap]

In normal operation can you have central heating on its own without having hot water ?