Worcester greenstar 30cdi ?

I had my boiler serviced last week and since then it sounds like it is constantly firing up 24hrs a day.Previous to this it was as quiet as a mouse and only made this sound when it was properly fired up,ie:hot water taps running or central heating turned on.It is driving me mad.The psi before was at 1.5,but the engineer set it to 1.0.Will this make a difference? Any ideas please to save my sanity!