Vibration noise from boiler

[GG55]

Hi folks I have a Worcester Greenstar CDI boiler which is about 7 years old. It has recently started making a vibrating noise periodically which can last from a couple of seconds to 60 secs at worst. It can happen throughout the day and night even when neither the heating or hot water is being used. The boiler is fitted onto an external wall and the noise is louder outside rather than at the actual boiler. Any ideas.

 

[ShaunCorbs]

Only way to tell is to get a gas safe engy to check it out when was it last serviced ?

 

[GG55]

Only way to tell is to get a gas safe engy to check it out when was it last serviced ?

Had it looked at by engineer about 1 month ago who said we had to change expansion vessel, which we did, and he also cleaned out a few tubes etc. He said that would fix it. It did seem to make the vibrations less frequent for a short while but have increased again.