Pipe diameter from tank for thermostatic shower?

[imsparticus]

What pipe diameter would you recommend to feed an unpumped thermostatic shower from a vented hot water cylinder via a new Essex flange? The run is approx 22 meters (up into the loft along and back down), the cylinder is fed via a 28mm cold inlet pipe and the cold water tanks are roughly above (2meter head) where I want to install the shower.

I was thinking of using 28mm but would it take longer to get the hot water that far compared to say 22mm?
All recommendations gratefully received.

Just for info we have another shower but much closer to the hot water cylinder that has good pressure so I'd be happy if i can match that.

Thanks in advance.

 

[Plumbstar Tom]

22mm should be fine i reckon

not a lot of head on that though

Try to use bends rather than elbow joints where possible

Consider using a pump though for a real decent shower

 

[stevetheplumber]

its the head above the highest part of the pipework you need to look at

 

[imsparticus]

its the head above the highest part of the pipework you need to look at

Thanks, can't do much about the height as I have 2 huge linked cold water tanks in the loft and the top of them are close to touching the rafters so can't go any higher.
I was worried that the run was so long that it would take an age to get hot water to the shower and be worse the larger diameter pipe I used. I'm trying to use a method that just in case the pressure isn't enough I can always opt to add a pump later.