While you wait for answers, we may have found some information which could help you.
Click here for Noise 10 Sound
How do I fix my boiler?
Netaheat 16/22 dripping water ! Ok to use or repair / replace ?
Netaheat electronic 16/22 not sparking have changed pcb?
No hot water from Netaheat Profile 50?
My boiler a Netaheat 10-16 "pulses" ?
Netaheat boiler 40E electric control?