Pilot light on my glow worm domestic gas boiler goes off as soon as boiler cuts of on thermostat.I have replaced the thermocouple but it is still shuting the gas valve . What can be wrong ,the gas vavle or thermocouple.please help.

It could be the pilot flame is not strong enough and when the main flames go out it snuffes the pilot lite with it. Your burner tubes could also need servicing. This is done on a complete clean and check of your boiler system. Cold weather is coming and most people never get there boiler serviced as long as it keeps running. I suggest a complete cleaning and service before the winter.

How do you put the pilot light back on ?