How do i drain my heating system

[vw754]

Hi, i have a Worcester combi boiler around 6 years old, radiators about 11 years old, i noticed in one radiator (when i took it off to paint) black water and tiny bits of dirt.

I want to flush the system with fernox cleaner and once all good, add fernox protector. I have 10 radiators.
Do i drain system from the actual boiler, then the radiators or one or both?

I have 3 radiators downstairs with drain off's, if that makes a difference.?

The recent radiator that i had in the new extension always seems hot at the top, warm at the bottom, its brand new, ive noticed if i turn one radiator off in that room, that gets hotter.....
Is it normal?

 

[Harry Bloomfield]

If the boiler is higher than the ground floor rads, there should be a drain cock on the boiler. Its worth draining all down and removing radiators in turn, to give them a good flush out outdoors with a hose, both forwards and reverse flow, until they run clean.

 

[vw754]

Boiler is downstairs.
Im not sure if i drain the rads do i need do it from boiler or the rads themselves, as 3 rads have drain offs.
Water comes out clean, unless i tip the rad on its side, then black comes out.

 

[vw754]

If 3 rads have a drain off.... Do all 3 need draining separately?

 

[Harry Bloomfield]

Boiler is downstairs.
Im not sure if i drain the rads do i need do it from boiler or the rads themselves, as 3 rads have drain offs.
Water comes out clean, unless i tip the rad on its side, then black comes out.

Drain from all possible drain points.

 

[vw754]

All 3 drain points off rads and boiler then.
Thanks for the help mate.