Hello Some months back (pre condensor boiler requirement) we rushed into having a ferroli combination modena boiler fitted but only now since finishing the kitchen have we noticed a problem. Its this. When the heating is on turning on the hot water tap cuts to hot water which is fine. However turning on the cold water also cuts off the heating. The boiler does not light up suggesting tripping of the hot water valve(?).We thought fitting a single check valve on the cold water feed into the boiler might solve the problem but it hasn't. Help and advice much appreciated.
Kaz