Angle of pipe from cold water tank

[Nick]

Hi Chris

I know the above, but it must be a pretty poor mains supply feed if the main tank is not at least about 2/3rds full, and so well above the bottom or outlet. By "in this context" I meant head is defined as the vertical distance between the water level surface in the tank to the shower head outlet. Naturally, when the water is flowing there are dynamic losses due to pipe friction and bends etc which would detract from this head.

If the tank were six feet deep and the shower outlet was at the level of the bottom of the tank, of course water would still flow, but some here are trying to suggest that this would be "no head", so water couldn't flow.

I didn't mean you to go to the trouble of writing out the grass roots.

Nick

[MarkK]

I agree with most of what you say Dave, but not the diagonal bit. Wastes loft space unnecessarily. Here's what I did when I re-plumbed my house, resulting in excellent shower performance:

Loft tank 1.5m off loft floor Main feed to DHW cyl 28mm DHW cyl specified with 28mm inlet & outlet + separate 22mm shower connection Pipes vertical from tank, then horizontal across loft floor then down to airing cupboard Full-bore ball lever valves in vertical section near tank. Separate 22mm cold feeds to each shower(2) & bath(1) All bends pulled - no elbows except where space restrictions make them necessary. I bought a cheap 15 & 22mm bender & hired one for a day for the 28mm work.

Result: very fast bath filling. Shower is the perfect compromise between pumped, which wastes a lot of water for no benefit, and the lowish pressure/flow from a standard header tank at loft floor level. To help people visualise the shower performance - if I hold the shower head horizontally at end of the bath it'll easily shower the other end.

As others have said, there's no issue with air locks in these horizontal runs. There's enough flow to flush out all the air the first time you open the taps. So whether you go diagonal or not is purely down to personal preference & what works best in your loft.

One other point worth bearing in mind - bends other than 90 degrees are a lot harder to get right.

Mark

[Christian McArdle]

What's the point of having a large tank if you anticipate never going below

2/3rds? You might as well fit a tank 1/3 the size.

If you design for the bottom of the tank, then it will definitely work when full. If you design for the top of the tank, things might not work if the tank is emptier. Things like shower pump flow switches might not operate and flow rate might drop off rapidly, completely wasting your tank capacity.

Christian.

[Dave Plowman (News)]

It's certainly a good idea - although costly. ;-)

[Dave Plowman (News)]

Depends on where the tank is - it may be possible to follow the run of the rafters. That's what I did.