Good thread this. If your taps are fed by the tank you will get the same pressure from both hot and cold taps, its only when the latter is on the mains (typically the kitchen) that there will be a difference. Generally fed by the water tank, to stop any suck back into the mains (ie contaminating your local mains supply).
Flusing (or reverse flushing) with mains water - exciting. I've only done this with cruddy radiators, but interesting to hear the eventual outcome.
Who needs to go on Screwfix or plumbers# websites for a good practical discussion.
I love this sort of thing [www.youtube.com