Hi, I have been having issues with my glowworm micron boiler. Last week it started to heat the water for a few minutes then cut out and I had to reset the boiler. Now it needs to be reset every few minutes. I have had two plumbers look at the issue. First plumber replaced the pump. He said the heated water was not getting away from the boiler, and therefore the boiler was overheating. New pump didn't solve the issue. Second plumber presumed that the was a blockage in the system. He powerflushed the system and cleared lots of black sludge. However the powerflush has not cured the problem, the plumber recommends replacing the boiler. It is s gloworm micron 60ff about 7-8 years old. It is an open vented system. I wanted to try and get another opinion before I bite the bullet and shell out for a new boiler . Any replies will be greatly appreciated. Thanks