heating pimp noise

Was recently woken up by my boiler making clunking screeching noises. After speaking to local heating guy, he thought it was the fan. We have now changed the fan, only to find after the boiler kicked in for a few minutes the fan started to make the same clunking screeching noises! Anyone have...

Hi Googled this as much as i can, but not found an answer. Also posted to grundfloss support, but did not receive an answer either. So I fitted a Alpha2 Pump to replace my old pump who's bearings were going and making a hell of a noise and it was nice and silent with the added benefit of...