Hi, Had this boiler fitted about 3 years ago without any problems.. until this week.. 1.Runs 7 rads and conservatory underfloor heating without any problems BUT now when the hot taps are turned on the boiler doesn't switch so therefor no hot water. 2.You have to "turn on" "turn off" several times and eventually it switches. The water is red hot at first then stabilizers. 3.Always had a water softner in place so shouldn't be lime scale damage. Mark.