thanks for the responses!
So I guess my options are to:
1. try the isolation valves first to see if the hot water will function once the heating has been isolated and partially drained
2. drain the upstairs rads, remove and cap of the existing pipes. re-fill the system to allow hot water...
I have a Vaillant Turbo Max Combi Boiler and a sealed heating system. I want to add a radiator and renew a couple of others which are not very efficient any more. For this I need to drain the heating system to work on the plumbing of additional radiator and exchange of others. But in the...