I have a conventional heating system. Had boiler replaced last August and since then my heating has made a humming noise - even when it is off. Had British Gas come go look at it but couldn’t hear it. I asked if it may be something to do with tanks in loft, but he said no and wouldn’t even go and have a look. A few weeks after I noticed that there was no humming. Eight weeks later I find bedroom carpet wet and water coming down the wall ruining wallpaper. I went up into the loft and water was dripping from tank and things nearby soaking wet. Got British Gas in again and they said ballcock needed replacing - which they did. The next day humming came back and once again heating sounds as if it is on when it is not. Any ideas please?