soot deposit on thermocouple

[digitaldes]

Hi hope someone can help with this intermittent problem !!

On a Thorn Apollo 30/50B , we have recently replaced the gas valve.

However , the pilot light now leaves a soot deposit on the end of the thermocouple which I assume restricts the heat getting to it , and therefore shuts down the pilot flame. When the soot is cleaned off it relights straight away and the boiler stays on , usually for about a week or a fortnight at a time until it builds up again.

To date I have removed the pilot gas tube & blown out any dirt & also renewed the pilot injector and bray.
The pilot flame is blue (no signs of yellowing - lack of air)
The main burner functions correctly .
Are there any other causes & solution of this problem I can try please?
Thanks ,
Alan

 

[WDIK]

yes you illegally worked on your own gas appliance,

how do i know?

because you didnt know you have to set and commision the new gas valve.

 

[gavinda]

im gonna sound really stupid here but.... when you say set and commision a gas valve do youu mean setting the burner pressure and adjusting the pilot size? ive never heard it referred to as commiioning the valve is all.

 

[ratonnastick]

My first question is are you qualified to work with gas.

soot or carbon build up is due to incomplete combustion and may relate to more serious problems with your boiler.

best advice would be get a registered engineer to check the boiler.

 

[WDIK]

im gonna sound really stupid here but.... when you say set and commision a gas valve do youu mean setting the burner pressure and adjusting the pilot size? ive never heard it referred to as commiioning the valve is all.

what term do use?

 

[gavinda]

dunno... basic checks and set up i guess . check tightness, bp/gasrate pilot if neccesary then fga. i suppose i only refer to commisioning inn terms of new boiler install, which i rarely do.

 

[WDIK]

dunno... basic checks and set up i guess . check tightness, bp/gasrate pilot if neccesary then fga. i suppose i only refer to commisioning inn terms of new boiler install, which i rarely do.

you have to set and commision the new gas valve

 

[Agile]

I would be quite happy with the term commission to cover what has to be done to a boiler when a new gas valve has been fitted.

Possibilities:

Recommision boiler.

Set up gas valve.

Adjust gas valve.

I wonder where the presumed illegal worker who started this thread has gone?

Tony

 

[gavinda]

dunno... basic checks and set up i guess . check tightness, bp/gasrate pilot if neccesary then fga. i suppose i only refer to commisioning inn terms of new boiler install, which i rarely do.

you have to set and commision the new gas valve

yeah.. i do set the pressure (max and that which its to be left on) check the fsd, etc. just never heard it referred to as commisioning. wondered if i was missing something

 

[digitaldes]

I have paid for the boiler has been checked on 2 occasions by corgi tradesmen. One of them just switched it on & claimed his £60 call out fee
as it burst into life staight away ! This is why I'm resorting to this method. At least I might be able to use your experience to point them in the right direction. Thanks to everyone who contributed to a useful response.