Bosch=Worcester - Greenstar 29CDI - Humming Noise on Morning Start-up

[Simon Fearn]

Hi

When my boiler fires up first thing in morning (either by drawing hot water or the CH coming on) the boiler makes a humming noise, similar to water knocking or when a valve isn't shutting off fully, for around a second or two then stops and doesn't do it again until the next morning. A recent service stopped in for around 5 days but then it has started again. Any ideas - I am not a plumber by the way but when the one I use comes out it never does it.

Thanks

Simon

 

[JohnD]

Take a video on your phone, recording the noise, and the display on the boiler, so you can show if to the mender.

 

[Simon Fearn]

The boiler doesn't show any errors and works just fine. It is just a very quick noise first thing in the morning.

 

[Alec_t]

If the system is starting up from cold it could be vibration due to something expanding.