Whistling/squealing boiler

[richig]

Hello,

Got a Potterton Suprima 30 non condensing boiler - vented y plan system with 7 rads and HW cylinder in air cupboard. All is well and fires up first time/regularly service (last time about 7 months ago). I have noticed that when it fires after about 5 minutes it makes a relatively low squealing noise. This lasts for about 10 min and then the noise is normal again. This only seems to happen in HW mode. In fact I can stop the squealing by turning on the CH. Both the CH and HW heat up fine.

Am I correct in suspecting the gas air mix or could this be something else?

Any suggestion appreciated. Thanks

 

[45yearsagasman]

Doubt it's a burner problem. Could well be heat exchanger noise. Very difficult to diagnose boiler noises from behind a keyboard. Need to be with the boiler to be precise.