High Pitch whine when boiler starts up?

We had a new condensing Glow worm boiler installed this time last year. Ever since then when it starts up it makes this high pitched whine for about 1 minute or two. It's only when the heating comes on not when it's just the hot water but having given up with the plumber cause anytime he came out it would't do it we just lived with it. BUT with this cold weather the heating is set to come on early and is waking us up before the alarm. Any ideas what it is ?