Something squeaking in Central Heating

purpleparrotuk

I have an unvented system with the tank and expansion vessel in the airing cupboard. For the past few weeks I have had just the boiler turn on twice a day for the hot water and heating has been off. 

When it’s been on for around 20 mins there is a loud squeaking noise for a few seconds. It reminds me when someone is getting out the bath and it squeaks because of the water. I haven’t a clue where it’s coming from and why it’s happening. Can someone please help?

Bendy_House

Make and model of the unvented tank?

I understand - but don't know - that some/all have either an expansion 'bubble' inside them (which needs resetting using a drain/refill procedure) or have external EVs. I'd imagine a 'squeaky' sound would most likely be related to that sort of thing? But that's pure guesswork.

Any chance of tracking down where the sound is coming from - the actual tank, or the EV?

Or, look up the instructions for that exact cylinder, and see if it says anything about this  recharging malarkey. Bear in mind, tho', that these systems need a G3 qualification to work on them. 

Can you see a pressure gauge? What does this show? Does it move much? Does it flicker when it makes this noise?

If you can record the sound, you could send the clip to the manufacturers. Post a link on here, too, as we have some plumbers who contribute.