Hot water from open vent pipe?

Hi all My parents are having some problems with their system and was after some advice.

This is exactly how my father has written it down

"Feed and expansion pipe from header tank rattles and vibrates and hot water gushes from open vent pipe when program on water but not on central heating."

Had new pump fitted 7 months ago

Obviously got to get a plumber in but would like an idea of whats up beforehand.

Many thanks in advance

Jon

Most probably a blockage around the feed and vent connections.

As AGM has said, it'll be blocked or restricted pipework. View media item 39013Your heating engineer will also need to check for correct circulation and boiler temperature control.

Great thanks for the quick replies guys ..ill pass this all on to my dad

Thanks
Jon