Hi Tom got another question

Thats normal sadek, if you drain from a down stairs radiator or a low drain off, everything above will drain if you let the air in, So the upstairs rads will drain but to make it quicker, undo the air vent ( bleed key) to drain faster,
The only one downstairs to drain is the one you drain from, the others can't because usually the pipe to downstairs rads come from above, and the water cannot go up to the joist level then down again , It can if it forms a syphon, but that can't happen in empty pipes and the circs will be empty,

I'll do one anyrode while its christmas