Myson Economist WM60/80 BF

[Iamtas]

My boiler is a Myson Economist WM60/80 BF running on gas

Pilot light goes low and hence thermocouple drops out but only after main burner has shut down i.e. system is hot. After unit is cooled pilot will relight to correct length of flame. It will remain lit indefinitely until main burner has come on and then gone off at which point the pilot can be seen to reduce in length then followed by thermocouple clicking out.

The original thermocouple was checked at 7mV but has been replaced as a matter of elimination, the volts drop across the limit stat is a maximum of 2.3mV

The problem started 3 days ago.

 

[gas4you]

Possibly blockage in pilot tube/injector. First course of action would be to blow through with air compressor to eliminate the simple

 

[Iamtas]

Wouldn't something in the pilot nozzle stop the pilot from being lit at all?

Is there anything regarding temperature that could cause the pilot to let out less gas when warm?

 

[pannierstan]

My boiler is a Myson Economist WM60/80 BF running on gas

Pilot light goes low and hence thermocouple drops out but only after main burner has shut down i.e. system is hot. After unit is cooled pilot will relight to correct length of flame. It will remain lit indefinitely until main burner has come on and then gone off at which point the pilot can be seen to reduce in length then followed by thermocouple clicking out.

The original thermocouple was checked at 7mV but has been replaced as a matter of elimination, the volts drop across the limit stat is a maximum of 2.3mV

The problem started 3 days ago.

Replace the pilot injector if you have already removed to clean.

Stan