just moved into a new house,i had the heating on yesterday, went to the bin to put some rubbish out and there was a rattling noise coming from the flue outside, and if u go in my sons bedroom wich is over the garage were the boiler is u can hear a faint whirring sound any ideas plz as to what it could be i think the whirring coulb be the fan but unsure of the rattling noise from the flue, its a ideal standard conventional boiler i think got a water tank and a tank in the loft any ideas much appreciated