I have a knocking heating pipe which I can't seem to stop banging. It only occurs when the heating first comes on in the morning and lasts for about 1.5 hours. This may sound strange but it seems worse when the outside temperature is lower. This only started happening when I laid some laminate flooring in one of the bedrooms that this pipe goes through. The pipe has feeds off it for the bedroom radiator. Any ideas that I could check?