What do I need to increase shower pressure?

[farticus]

I have one of these......... https://www.plumbworld.co.uk/mira-event-xs-thermostatic-191-32529 A tad expensive but it's a brilliant shower. Mine is an older model as I do not have an on off switch. Absolutely oddles of power from it. I have two cold water tanks in my loft though. They were there when we bought the house 3 years ago as was the shower. I'm told by a plumber that the second tank is to feed the shower although that is the only explanation I have had. As long as it works I don't care.

That's the sort of thing I'd like, with separate controls for the pump and the thermostatic valve. No need to have max power all the time. The guy doing our bathroom recommended Mira too.

 

[MNW67]

All 4 pipes go to the loft.

1 - Hot, bottom of cylinder
2 - Cold, top of cylinder
3 - Cold, mains feed from bottom, pressure vessel and boiler via he flexible hose
4 - Disconnected

I'm fairly sure 3 is fed from the mains. There is a tap that I believe is the stop cock, but it's stuck so I can't confirm that. Will probably leave that to the plumber. I installed the Eddy descaler thing, it seems to have had an effect which confirms that is the cold feed.

Pipe 3 should be the mains feed and would normally be filling the cold water storage tank in the loft.

I would have thought 1 & 2 would be the other way around. The pipe coming out of the top of the cylinder should be hot. The pipe coming down from the loft tank into the bottom of the cylinder should be cold. I am guessing there is another pipe somewhere from the loft tank which takes a cold feed to the shower.

 

[farticus]

Pipe 3 should be the mains feed and would normally be filling the cold water storage tank in the loft.

I would have thought 1 & 2 would be the other way around. The pipe coming out of the top of the cylinder should be hot. The pipe coming down from the loft tank into the bottom of the cylinder should be cold. I am guessing there is another pipe somewhere from the loft tank which takes a cold feed to the shower.

I think that's right about pipe 3, it goes to both the pressure vessel/boiler and the loft.

I doubled checked and 1 is definitely the hot one, and definitely goes to the bottom of the cylinder. We have an immersion heater in that tank, but it's only for emergency use when the boiler is not working for some reason. It's not very hot, just a little warmer to the touch than the other one.