Boiler won't stay on

[bobbydazzla]

I have a problem with my boiler....

initially the pilot light wouldn't stay on, so I read through these forums and that made me think it was the thermocouple that had gone.

however, having tried a few more times to start the bolier I have been able to get the jets to fire up and the boiler to come on but it appears that after about an hour when the thermostat kicks in, the boiler switches itself off.

does this situation also indicate that its a knackered thermocouple ?

as I'm a DIY moron I havent tried to fix the thermocouple myself.

 

[chrishutt]

I'm a DIY moron

Evidently. It might help if you tell us what boiler you have.

 

[bobbydazzla]

its a saunier duval thelia 623

 

[chrishutt]

when the thermostat kicks in, the boiler switches itself off.

That's supposed to happen. What exactly is the problem.

 

[bobbydazzla]

the problem is that the boiler shuts down, the pilot light goes out and the bolier will not automatically fire up again.

I have to manually restart the boiler.

 

[chrishutt]

That's the overheat stat cutting out. Nothing wrong with thermocouple. You need a good heating engineer who knows Saunier Duvals. Many don't like S-Ds and will just say replace it.

 

[bobbydazzla]

cheers. although it doesn't sound like good news. have a friend of a friend who is corgi regged and he has already suggested that an SD bolier isn't in favour with plumbers....

one fnal question, would the difficulty in initially firing up the boiler also be a symptom of the overheat stat being knackered ?

 

[bones001]

firstly check the size of ya pilot flame and that it completley engulfs the tip of ya t.c. if it is and it still won't stay lit check for continuity on the interupter/overheat if it has one. if the overheat has continuity i would change the thermocouple although u can make sure by unscrewing it from the gas valve and lighting the pilot get ya multimeter and put one probe on the tip which came out of the valve and they other on the actual lead while still holding the pilot in you should get a reading of about 20mvdc if its about 15mvdc or less change the thermocouple. now you say it cuts off after a while which may mean it is overheating, if u manage to get it going again, turn the boiler stat down to 1 and see if it cuts off and leave es the pilot lit this way you will know the thermostat is working correctly.

 

[chrishutt]

would the difficulty in initially firing up the boiler also be a symptom of the overheat stat being knackered ?

I never said the overheat stat was knackered, only that it was tripping, probably because the boiler is overheating! This could be due to poor circulation, possibly due to weak pump (S-D pumps tend to get clogged up with black oxide) or clogged waterways.

 

[bobbydazzla]

the boiler has now started working properly again. the pilot stays on and the system doesn't totally cut out when the thermostat kicks in.

I didn't do anything to sort it out either.

might still get a corgi registered mate round to give it the once over....