I have a loud banging noise comming from boiler when temperature at thermostat is set to 18'C or above. I have been told that my pump was failing (bearings on way out) and that was causing the system to kettal. System should not need to be de-scaled due to soft water in area. Also have noticed that when the temperature in the room drops the heating does not come back on (after system has been kettaling) and that the hot water control does not switch off when it is set to (just appears to stay on). Can anyone tell me if this sounds like the cause of my probem and if it is all related to a failing pump or wheather or not I have seperate problems with my system. Thanks.