On 2006-10-31 19:45:58 +0000, "yogi" said:

Thanks Andy. I had planned to have the bottom of the CWT tank about
18" higher than the bottom of the HW cylinder (so the top is only
slightly higher that the HWC), but I wasn't sure if that would be
enough to push water out the top of the HWC. Looks like I need to raise
it higher so the bottom of the CWT is higher than the top of the HWC.



That's really the minimum viable situation and gets you to the point
that the cylinder will be full.

The other thing will be to put in a 28mm pipe to feed water from the CW
tank to the cylinder.
The effect of this will be that when you draw HW from the 22 or 15mm
pipes from the cylinder, the flow
rate can't exceed that between the CW tank and HW cylinder. If you
don't have that then there is
a fair chance that the level in the vent pipe will drop and air will be
sucked in.

While you are doing this re-work you could look at running 22mm pipes
(hot from cylinder and cold from tank) as close as you can to the
shower. This may well improve flow.

The exercise as a whole won't improve pressure. That would need a
mains HW system or a shower pump.

Don't forget that water is very heavy. If you are going to raise
the CW tank and support the HW cylinder, there need to be substantial
timbers and positioning over a load bearing wall. It is not something
to put in the middle of an area on a few 75x50 joists.