How do i drain a microgenus he combi(heating only)?

[stuckinlimbo]

I have the above combi and i have the manual.In the manual it shows me where the drain valve is( is it inside the boiler with a white end cap on?),if so how do i access it and then how do i drain it? This is to drain the system to replace an end valve on a radiator.
Thanks
Gary

 

[EliteHeat]

Just drain it using a drain-off valve.

 

[stuckinlimbo]

thanks but what and where is the drain of valve.Is it one thats on the rads?
Thanks