I purchased a full central heating system in April 2005 and opted for a Glow worm 30CXI boiler. I have had nothing but problems. Three new heat exchangers, one new circuit board as it blew and new overheat sensor. It has been flushed twice, but still having problems. According to Glow worm there is dirt in the system and it has caused ALL these problems and now refuse to repair it! The boiler is apparently made by Valliant so that's their problem. The system was not installed by Glow worm so installation problems are not their's either. What do they do exactly? Anyone had similar experience?