Loud squealing noise from sealed system – expansion vessel? Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[Hankhill]

Has anyone ever heard this noise coming from a sealed central heating system? See - https://youtu.be/1IGz-HjDJPo

The noise reminds me of air escaping from the neck of a balloon. It happens almost daily, for a minute or so, normally while the hot water (Megaflo) is on (heating is off as its summer). I can stop the noise by opening the tap used to top up the water pressure, as in the video.

I strongly suspect that it’s the expansion vessel that has failed; the plumber on the last service did have to top up the air and it’s been making this noise ever since. I was just hoping for confirmation from someone that has heard this before.

[stoneyboy]

Hi hankhill,
I suspect it is the pressure relief valve, check by holding a length of wood (a broom handle is ideal) against your ear and touch the other end on each system component and see if you can identify the source.
Regards S