Noisy boiler on warm up

[Steveuk]

I have got a baxi WM 30/ 3RS boiler. Recently had it serviced where the chap cleaned it and adjusted the gas, But since he did it every time the boiler starts from cold it makes a banging popping sound for about half an hour then goes quiet but it works fine. Any ideas what is causing the banging sound?

Thank you

 

[ShaunCorbs]

might be worth asking him to come back due to the loud ignition

 

[Steveuk]

I don't know if its the ignition, it starts and lights ok, but its for half an hour or so after that. It seems to stop once the boiler and water is starting to get up to temp.