Noisy central heating

[Northy]

Hi guys, hope someone can help.

Every morning when the central heating kicks in it is very noisy, the noise is coming from the airing cupboard and sounds a bit like a pump that is catching as it spins, does that make sense?

The noise gets gradually quieter until its gone as the system heats up.

Any ideas? Is it fubar'ed?

Cheers,

G