UK Plumber Forum

[Simon1966]

There is a small silver box, with power attached, connected to pipework near the main Greenstar water tanks. When the heating comes on it makes a repetitive banging sound. What’s it for and what do I do?

[REDSAW]

its a port valve.
the top comes off the valve and can be exchanged.it may be the rubber ball inside the valve which may have broke away causing the rattling.
change the top for the same type first, if no improvement then the valve body nedds changing too by draining off system.
the rattling could also be scale in the system and not necessary the valve itself though!

[Best]

Motorised valve head (actuator) slipping inside?
Might just need that part replaced