When the central heating is off and the water is off there is a constant noise from the airing cupboard (very bad at night when everything id quiet)noise can also be a whooshing every now and then. When I turn the grundfos valve down from 3 to 1 the noise stops and it is quiet. Problem with this is that the heating does not work in the morning when it should come on so house is freezing. To get all rads working again have to let out air in the 3 pipes next to valve in airing cupboard. Please help.