Fan running continuously?

Hi
I have moved into a rented house, and there is a noise from the boiler whenever the Programmer is switched on, even if the boiler is turned off!
Have replaced the EP2002 programmer with an EP2 thinking that may have been the issue, but the noise id still happening.
Is this the fan running continuously? Also, are these boilers gravity fed or fully pumped?
Thanks in advance for any help...