Noisy w/hand basin waste pipe

[hemelhandyman]

I have a w/hand basin that, after the usual 'gurgling' as it completely empties, continues to 'burp' (it's the best way that I can describe the noise!) for a long period. The noise comes from the outlet but is definitely being generated from somewhere within the drainage pipes (it has a P trap).

The strange thing is that this only happens when hot water is poured into the basin, and the brief pouring of cold water into the basin solves the problem. Can anynone please explain why this is happening and what can be done to solve it?

Confused!

 

[LUNAT]

HI

remove old trap and fit new anti vac trap (mcalpine)if this is not possible you can fit anti vac trap anywhere in the waste pipes (not main soil pipe).