dripping drain off on vented central heating

[Mgrant]

If a drain off valve is leaking on a vented central heating system, due to not shutting off. As the washer has perished. Has anyone had success in swapping the inners over in this without draining down, if quick?

 

[Rob Foster]

If a drain off valve is leaking on a vented central heating system, due to not shutting off. As the washer has perished. Has anyone had success in swapping the inners over in this without draining down, if quick?

Do mean an mt cock ? Its a drain for heating system located below the head of water for the system. .Rob Foster aka centralheatking

 

[heliotrope]

9 times out of 10 the old washer will be left behind and is tricky to get out. So not too easy to snatch.
Better off to bung system or drain down.

 

[Mgrant]

just a 1/2" drain off cock.

 

[king of pipes]

Got a picture of it you can swap em but need to lock the system up or it's a drain down job. Kop

 

[Best]

I have had to unscrew and remove the brass part and sometimes poke a small slotted screwdriver in the drain to break/remove the old washer.
This is a good reason for not using soldered draincocks, but rather 1/2” threaded into F.I. fittings where suitable, so the entire draincock can be swapped easy