Hot water cylinder and pressure ?

[johnad]

I'm moving a hot water cylinder at the moment the pressure on the hot taps is fine the tank is at floor level in the bathroom with the header tank in the loft directly above.
When re-plumbing I have the oppotunity to raise the level of the cylinder or even to move the whole lot into the loft above although if I do the latter it will mean that the header tank is only just above the cylinder what would be better to stay with a good hot water pressure ?
Is it worth raising the hot water cylinder ?
The only other thing that will chainge is that I intended to run the hot and cold pipe work feeding the bathroom up from the tank across the hall and back down behind the bathroom door.
Will this affect pressure or will I be better off chasing the concrete floor and running them that way as this is the current setup ?
Advice appreciated please.

 

[TicklyT]

The position and height of the hot cylinder makes no difference to the pressure at the taps. The static pressure is determined by the height of the cold storage cistern feeding the hot cylinder.

Locating the cylinder too close to the height of the cold storage can lead to problems with airlocks caused by air drawn down the hot cylinder open vent.

Adequate bore pipework is essential for a gravity system to deliver good flow rates with the limited pressure available. That usually means running 22mm from hot cylinder to bath filler

Oversized pipework, or longer than necessary pipe runs increase the amount of water you will run to waste before hot water arrives at the taps.

 

[johnad]

Thank you for your reply
Will The up and over pipe runs I mentioned cause me problems or is it better and wise to run to the bathroom under the concrete floor ?
The run will be about 3m.
Is it ok to run copper under a solid floor ??
Thanks again

 

[TicklyT]

Three metres isn't exceptionally long, so that shouldn't be a problem, but 'up and over' runs may be prone to airlocks, unless arranged with a constant rise towards the cylinder vent or a seperate ABV

Copper pipe and concrete, or other cement products in intimate contact aren't a good combination - the cement corrodes, and soon pinholes the copper.

Copper pipes should be sleeved or run in a duct rather than laid directly in floor screed.