Plumbing – Should these valves stop the hot water

I'm trying to shut off the hot water supply to repair the kitchen tap. Unfortunately I can't see any isolator valves near the tap, so I'm puzzling over how to shut off hot water for the whole house.

I tried to do a bit of research into how our heating & hot water system works, but I may be getting this wrong, and to be honest I'm kind of tempted to just post the question "What the heck do all these pipes do?", but I shall try to be more specific.

It's a F&E system with two tanks in the loft and hot water cylinder in the first floor airing cupboard, which looks like this:

So according to these instructions I need to close a valve which feeds cold water into the bottom of the cylinder. "This valve should be easily recognisible as a valve with a red, wheel-shaped handle on a pipe that runs from the ceiling of the airing cupboard to the bottom of the cylinder."

The valve in the top-right (just above the top shelf) seemed to fit that description, so I tried closing that.

Then I noticed valve in the bottom left could also fit that description, so I've tried closing that too (although I may be misunderstanding the direction of flow there)

I notice there's three pipes leading into the bottom of the cylinder. The third one slightly higher on the left is hopefully shut off by the motorised valve (I have the heating and hot water switched off)

I then try running the hot tap for a minute or two, but it's showing no signs of stopping. Do I just need to wait longer for pipes to drain out? I tried the same on the 2nd floor bathroom because I thought it might stop flowing quicker there, but …no sign of stopping.