Does anyone happen to have a manual for one of these to hand please ?

(I don't know which specific model it is from the range atm)

I'm just trying to work out what's making it run so noisily - the rads
are bled, but even with them off it sounds like it's pumping a huge
amount of air around the system (gurgling like a b*stard to be more
precise)

I've just tried to lower the temp at the boiler end in case it was
kettling causing it (don't normally notice if it is, as it's in a
garage)