We have a Ariston 24he microgenius mffi condensing boiler installed in the house, there are no external controls present. When we switch the boiler on to provide heating after a few mins the boiler starts making a high pitched squeeling sound, which reverberate through the pipework in the house and makes a really damn awful and annoying sound. When we run the tap the sound ceases due to the combi switching to HW demand. Any idea what could be causing this noise plz?
