Can someone pls suggest anyting.....Hot water till today worked a treat. Now if I switch on just the hot water tap, i get hot water for about a minute before it goes cold - the boiler shows no red light and if i switch the tap off and back on again after 10 seconds or so i get hot water again for about a minte before it goes cold again HOWEVER if i turn on the hot water and cold water taps then i get luke warm hot water without any problems and the bolier keeps working. Any ideas ?