vaillant combi boiler Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[waterman]

hi all i have a vaillant 831 ecotec plus condensing combi, fitted august 2008,now and then it makes a loud buzzing noise like a very large bee is inside the boiler,but when i open hot water tap for a second or two it stops.any ideas to remody this would be appreciated.thanks.