Combi Boiler banging when switching on

[Actionmainly]

I have a Vokera compact 28 SE combi boiler which is about 4 or 5 years old. The issue is whenever it turns on it makes quite a loud noise. A bang is maybe a bit of a strong word but it's like something hitting the metal casing of the boiler and causing a thud. It didn't do it when it first got installed and has gotten steadily more pronounced over time. Any ideas what might be causing this?

Also a second issue is if I run the hot water quite slow there is a terrible rattle from the boiler. Not sure if it's the flue or the boiler itself but it's definitely only when the hot water is run slowly. If I turn up the pressure on any tap it stops rattling. Not as big an issue but still annoying. Any advice what could be causing this?

 

[Razor900]

When was it last serviced?

 

[Actionmainly]

I think a couple of years.

 

[Agile]

I would wonder if the boiler is properly controlling the heat input.

Regardless it seems that it is likely to need a competent boiler engineer to diagnose the fault.

It sounds to me as if it has never been serviced! That is because if it had been then that issue would have been investigated by the engineer.

Tony