flame keeps coming on then out and evrey few seconds ?

I have same problem fewday ago finally reading different post come to know few things as after reseting it start and after a little burst voice comes and it stop again no heating and hot water.
if u look in bottom of boiler one piece of plastic pipe is attached this could b cooper as well in some boiler whos other end left open out side wall or that will b connect with drainage as this pipe take off exast condense water if this pipe is block combi boiler dont start. Need to b some presure thingi to blow up blockage. If u see in bottom of boiler one plastice container whos filled with solid parts of dirt this pipe is attached with one its very easy to take off from side u see a slider hook just push out and it will split half litter of dirty water out need to wash it and place back to its position as it is attached only with two hooks. After doing this urs boiler will b ok. Keep an eye on boiler pressure gauge it should remain between 1 to 2 in normall

Eric
January 2014

check the pilot flame is it a good flame onto the thermocouple before and during the main burner being lit,sometimes the main burner draws air from the pilot and pulls the flame away from the thermocouple

toptrish
December 2013

Change air pressure switch also clean ignition spark rod

ltd
December 2013