Another way to drain central heating while drain cock is rusty and unscrewable

[michael2008]

I want to unscrew the drain cock of my central heating system. But the drain cock is so rusty and couldn't be unscrewed. Is there another way to drain the system? Thanks for helps!

 

[welly2510]

if its the only one on the system and its siezed you could use a self cutting drain tap, then you can either leave it on the system or cut out the existing one and replace that.