Leak from valve on filling loop

Hi,

Worcester 30cdi system boiler, sealed system and unvented hot water.

Last couple of times I've topped up the system, I get drops of water from the screwdriver slot isolation valve bit, where my screwdriver is on the pic.

It's no problem because there's another isolater on the same valve.

Am I allowed to change this valve myself on an unvented system? It looks as though it's on cold water side, am I right in saying if I isolate the cold water I won't spill much if I just change the valve and not the whole filling loop?

If I can do it, can I buy that valve on its own and what's it called?

If I can't do it, I presume I'm ok to leave until next service due in Summer, it seems a very simple job to call someone out to (especially as the leak only happens when topping up).

Thanks in advance for help.

A new filling loop shouldn't take too long to fit and no qualifications needed.

Make sure double check valve end is on the cold water supply end, drop pressure off the system and you can check for any back flow of heating water by putting the old filling loop end over a bucket.

Filling loops can be a nightmare for leaking.

According to the Ministry of Silly Walks... they’re not actually meant to be left attached - removing it and capping the ends of the fixed pipework will resolve the issue. If you have to regularly top up, there are other issues at play.