hot water?

since a plumber came round to service our boiler he turned the pressur either up or down on the water by a switch which is behind the cooker because when u ran the hot water it were really noisy and since this weve had hot water down stairs and only tepid water upstairs and the boiler is in a cupboard under the stairs and its been making a vibrating noise but u can hear it faintly from boiler and louder when stood on the stairs its a glowworm compact 80 p combi