when only use hot water .it seem be ok . when I turn on the cold water tap slowly still normal. but if turn the cold water tap quicker. the boiler will stop working .then couple of second it will start working back .anyone can help me for this .thank you very much.

danny, September 2014

I did . toptrish ..the same

danny, September 2014

It sounds like it is reacting to a sudden drop in pressure,check that stop cocks are open fully

toptrish, September 2014