Saunier Duval SD623: Flame goes off and on when boiler is on high setting?

Brian Murcott
brianmurcott@talktalk.net
I have been having the same problem for the last two months. Had the gas board in six times to fix it, put three different parts, but still the same. new senors fitted for the hot water and central heating. Now telling me there is a small hole in the flue, and these cannot be found, the unit needs to be changed. This is the first full winter it has been used in the past 12 years, as it is normally switched off for 4 months each, winter, as we are away. As I know noyhing about it, what can I do.

Brian Murcott
January 2008

It`s not the flue pipes I was referring to but the heating pipes, on the left of the boiler there are two pipe and three hoses within these hoses could be the blockage, back top is favourite. the pump cannot move the water from the boiler so it kettles and overheats. there is also the hose from the jig to the reversing valve try the others first.

alan
December 2007

It`s not the flue pipes I was referring to but the heating pipes, on the left of the boiler there are two pipe and three hoses within these hoses could be the blockage, back top is favourite. the pump cannot move the water from the boiler so it kettles and overheats. there is also the hose from the jig to the reversing valve try the others first.

alan
December 2007

Thank you Alan. Engineer came out again and cleaned flue pipes (no obstruction found) and tuned boiler output down. He didn't open the burner but this was cleaned recently. Circulation seems ok though he commented that pump might be too warm so may be not working as well as it should. Boiler seems to be working better but not sure why - but I am not complaining!

Denis
December 2007

Possible blockage in the pipework, carbon build up, poor circulation.Check hose connections on the boiler

Alan Corbet
December 2007

Possible blockage in the pipework, carbon build up, poor circulation.Check hose connections on the boiler

Alan Corbet
December 2007