Unvented cylinder loud humming noise

[Dorsetdweller]

I have an unvented heating system that was installed just under 3 months ago.

In the last few weeks the HW cylinder makes a very loud humming/vibrating noise when the HW pump for the secondary feed is on, but makes no noise if the CH is on at the same time.

The noise fades in and out and sounds like an aircraft is overhead

Any ideas what may be causing this please as it’s driving me mad

Many thanks

 

[Harry Bloomfield]

It could be a problem - out of balance, or etc. of the secondary pump. Get the installer back to investigate.

 

[Madrab]

Put your hand on the secondary pump when it does it, does it vibrate 'in time', if so it'll be resonance and may need adjusting.

As suggested though, get the installers back out, it really is for them to investigate.

 

[ianmcd]

I have had this and it was the kitchen HW tap that was causing it, when it makes the noise go around the HW taps and open one at a time to see if it stops the noise