Removing dual fuel towel rail to replace element

[Testing Times]

I need to remove towel rail to replace element which has burnt out.

Dual fuel valves are the type shown below.

I'm fine with isolating the radiator, but unsure how to disconnect it from the two valves to drain then lift off. Do I loosen the top collar (red arrow) or middle section (green arrow) ?

Also would be grateful if anyone could recommend the correct type of wrench / grips for this. Seems very narrow - is a spanner best?

Only recently gained the confidence for DIY plumbing - please go easy on me and any help appreciated.

Dual Fuel Radiator Valves Set​

Our dual fuel valve sets are manufactured from heavy duty brass with a polished chrome finish. When the valves are purchased with an electric element you can convert your new or existing towel rail or radiator to a dual fuel system.

 

[endecotp]

You can unscrew the heating element from the valve, leaving the radiator attached to the wall.

 

[Testing Times]

There's only about 100 mm clearance to the floor, so won't get it out or the new one in.

 

[endecotp]

Interestingly, the photo you’ve used agrees with their tech drawing but all their other photos look different.

I believe there is probably both a valve and a tail there. The top nut screws the tail into the radiator, and the bottom nut screws the valve onto the tail. Or something! Hopefully someone who knows more than me will be along soon.

I recommend putting something soft between your spanner and the chrome.

 

[polesapart]

Drain system, undo the third nut on both valves,loosen the brackets and pull the bottom of the radiator forward an inch. Undo brackets and remove rad from wall.

 

[Testing Times]

Interestingly, the photo you’ve used agrees with their tech drawing but all their other photos look different.

I believe there is probably both a valve and a tail there. The top nut screws the tail into the radiator, and the bottom nut screws the valve onto the tail. Or something! Hopefully someone who knows more than me will be along soon.

I recommend putting something soft between your spanner and the chrome.

I know, it's weird.

Their photo that I posted, my actual setup looks like that

 

[Testing Times]

Drain system, undo the third nut on both valves,loosen the brackets and pull the bottom of the radiator forward an inch. Undo brackets and remove rad from wall.

I was hoping to isolate and drain the individual radiator only. Do you think that's not possible?