leaking isolating valve

[nebberchadnezzer]

Hi,
would really appreciate some advice, i have a potterton Puma 80 combi boiler, which despite its age works fine, but the return isolator valve has started to leak from the plastic tap switch, what is the best way to change it (does the whole system need draining or just the boiler. cheers

 

[ChrisR]

WHole system, sort of, though if you close the other iso valve the water should hang in the pipes if air can't get in. Towels & buckets!

 

[superdupergasman]

Change them both, sure as fate, change one, next week other will leak! your going to drain a bit of the system anyhow!!