draining the system a little to replace a rad

[soccercelt]

Ive to replace a rad and a leaky rad valve on a rad in y upstairs bedroom. Its been leaking for a few months and seeing as im free today, i might aswell get cracking on with it. Anytime i change a rad valve upstairs, i would half drain the system then change the rad/valve. One question i have concerning this is that its a duel system connected to a stove in the living room. Im 90% sure it isnt anything else needing doing apart from filling up again like normal, bleed rads etc.. however i thought best to ask here first.

 

[Headrush]

I'm assuming it's open vented...

You could try capping the expansion at the F&E tank with a push fit fitting, bung the tank outlet with a rubber cork and just drain the rad in question, the rest of the system should airlock itself.

 

[king of pipes]

I would turn off the rad valves drain out the rad with a wet vac , lock the system up as above then change the valves one at a time cheers kop

 

[Best]

You could just drain the top half of system as you normally do, if you wanted to, - dual system shouldn't make any difference.
But as the other replies stated, you just need to bung any vents and feed pipes at f&e tank. The vent pipe might be directly from the stove primary flow, but it still needs bunged.
Just take the pressure off the system from a draincock low in the system and you should have no bother with upper floor radiator valves. Getting the old rad drained is the hardest part.
Don't forget to remove all bungs and add inhibitor