Turn the hot water on - burner ignites water starts to get hot then burner goeas out after around 30 seconds - water goes luke warm/cold - continue to run the tap and after around 20 seconds burner comes on again water heats up then - yes yet again - burner goes out. It will do this continually for as long as you have the hot tap running!!!! Have seen a lot pointing at Diaphram possible secondry heat exchanger needing cleaning but any firm ideas as to what the problem is???????? - two young kids not a lot of spare cash to pay a plumber have the boiler manual and am pretty nifty with mechanics and stuff so any firm answer will be appreciated - should be easy enough using the manual to replace whatever componant needs replacing/cleaning!!!

ed, April 2008

it will be secondary heat exchangewr blocked up required removing cleaning,used costic soda be very careful and replacing both heating and cold water supplies require isolating be carefull of leads two thermistors undo first as if pulled could cause damage

tony, April 2008