Worcester bosch cdi humming intermittently

[Blaine1944]

Hi, got a 10yrs old WB greenstar 37cdi. Runs nicely but every few minutes has a loud buzz that fades in then back out, lasts for a few seconds or minutes
and then fades out. Definitely not the pipe work or snagging. Can happen any time, not just upon fire up or shutting down. Any ideas? Thanks

 

[Dangee]

Hot water preheat? Put on to Eco & see if it still does it. Good boiler.

 

[Blaine1944]

Hi good shout, unfortunately the boiler is always in Eco mode as We have an old fault where the pump spins constantly (24/7) if Eco is off. Non of our engineers have ever understood it so they just advise to keep Eco on. I think I need a new pump. Any advice on pump noise anybody?

 

[Dangee]

Change pump?

 

[Blaine1944]

Yep!

 

[martyndc88]

Pcb for pump issue