Noisy boiler

[schmalex]

We've just moved to a rented house and the boiler is very noisy, especially first thing in the morning when it's cold. It makes a sort of howling noise. It's an Ideal Icos, just a normal boiler not a combi.
We're waiting for the letting agent to send a plumber as we've also had problems getting the downstairs to heat up - I'm not sure if this is related or not but a few of the radiators downstairs are very slow to heat up.
Any ideas?

look under the boiler towards the right hand side. If i remember correctly the icos has a pressure gauge. It should be set to 1bar-1.5bar. Thats the easy fix. Otherwise. Maybe a worn fan or pump (neither are diy jobs)

Thanks Salty, but there's no pressure gauge (isn't that usually on a combi?).