[Andrew Baker]

Wanting to install a new shower, I'm trying to understand water
pressures...

My cold water is all direct from the mains (no tank). United utilities
say they supply it with at least 7m static pressure. Does this mean it's
at least 0.7 Bar, then?

Hot water is fed from a tank. I've a non-combi boiler that's
pressurised, but that's just the heating circuit, I think. The hot water
tank is in the cellar. I _think_ there's a header tank for it in the
loft, though I've not actually heard it filling when the hot water is
running (further tests tonight!).

(Is it possible that there's no header tank and the cylinder is fed
directly from the mains? I don't think the hot water is pumped in any
way - just the CH)

Assuming it is a loft tank, can I estimate the hot water pressure as
being the distance from where my new shower head will be to the tank in
the loft?

So, with a shower downstairs, and the tank in the loft in a high-ceiling
house, that'll be something like 5 or 6 metres, meaning a pressure of
about .5 or .6Bar?

Does the fact that the tank will be below the shower head make a
difference? Will the 'resistance' of all the pipework make a big
different to that 0.5Bar figure?


Or am I completely offside and misunderstanding?

[The Natural Philosopher]

Andrew Baker wrote:
Wanting to install a new shower, I'm trying to understand water
pressures...

My cold water is all direct from the mains (no tank). United utilities
say they supply it with at least 7m static pressure. Does this mean it's
at least 0.7 Bar, then?

Hot water is fed from a tank. I've a non-combi boiler that's
pressurised, but that's just the heating circuit, I think. The hot water
tank is in the cellar. I _think_ there's a header tank for it in the
loft, though I've not actually heard it filling when the hot water is
running (further tests tonight!).

(Is it possible that there's no header tank and the cylinder is fed
directly from the mains? I don't think the hot water is pumped in any
way - just the CH)


Yes..its possible. The tank if it does run at pressure will have a lot
more pipes and safety valves on it.

Assuming it is a loft tank, can I estimate the hot water pressure as
being the distance from where my new shower head will be to the tank in
the loft?

Yes.

So, with a shower downstairs, and the tank in the loft in a high-ceiling
house, that'll be something like 5 or 6 metres, meaning a pressure of
about .5 or .6Bar?

Yes.

Does the fact that the tank will be below the shower head make a
difference? Will the 'resistance' of all the pipework make a big
different to that 0.5Bar figure?


No. Some.
Or am I completely offside and misunderstanding?
No. You are IMHO spot on.

[Christian McArdle]

(Is it possible that there's no header tank and the cylinder is fed
directly from the mains? I don't think the hot water is pumped in any
way - just the CH)

Yes. That is possible. If you can post a photo, or post what the writing on
the side says, we can give a better idea.

Assuming it is a loft tank, can I estimate the hot water pressure as
being the distance from where my new shower head will be to the tank in
the loft?

Yes.

So, with a shower downstairs, and the tank in the loft in a high-ceiling
house, that'll be something like 5 or 6 metres, meaning a pressure of
about .5 or .6Bar?

Yes.

Does the fact that the tank will be below the shower head make a
difference?

No.

Will the 'resistance' of all the pipework make a big different to
that 0.5Bar figure?

Yes.

However, 0.5 bar is unacceptable for a shower in my opinion, although it is
fine for a bath if the flow rate is acceptable. It will also drop
dramatically when the flow rises. I would install a pump.

Christian.

[Andrew Baker]

In article , cmcardle75
@nospam.yahooxxxx.co.uk says...


However, 0.5 bar is unacceptable for a shower in my opinion, although it is
fine for a bath if the flow rate is acceptable. It will also drop
dramatically when the flow rises. I would install a pump.


Can I do that, though, given the cold isn't tanked? (I can't pump mains
cold & pumps seem to all be dual hot&cold?) Plus, I presume that would
mean running a direct feed back to the tank, which is a pain. (Yes -
much better in terms of flow etc, but a pain..)

The current (upstairs) shower isn't pumped and is actually quite good..

[The Natural Philosopher]

Andrew Baker wrote:
In article , cmcardle75
@nospam.yahooxxxx.co.uk says...

However, 0.5 bar is unacceptable for a shower in my opinion, although it is
fine for a bath if the flow rate is acceptable. It will also drop
dramatically when the flow rises. I would install a pump.


Can I do that, though, given the cold isn't tanked? (I can't pump mains
cold & pumps seem to all be dual hot&cold?) Plus, I presume that would
mean running a direct feed back to the tank, which is a pain. (Yes -
much better in terms of flow etc, but a pain..)

The current (upstairs) shower isn't pumped and is actually quite good..

Then you may well be all mains pressure.

I header tank in the roof is just about capable of running a ground
floor shower in a 2 storey building..but you need more than the 4-6ft
head from a tank in the roof to an upstairs shower..

[Biggles]

The Natural Philosopher wrote:

I header tank in the roof is just about capable of running a ground
floor shower in a 2 storey building..but you need more than the 4-6ft
head from a tank in the roof to an upstairs shower..

Depends on your priorities. You don't need more than that to get a
shower you can get clean under, although you do if you want it to be
"invigorating". The greater the pressure, the more water and energy you
will use.

Biggles

[David Hansen]

On Wed, 05 Jul 2006 01:36:12 +0100 someone who may be Biggles
wrote this:-

Depends on your priorities. You don't need more than that to get a
shower you can get clean under, although you do if you want it to be
"invigorating". The greater the pressure, the more water and energy you
will use.

One will buy energy if one adds a pump. However, one will not buy
energy if using a venturi shower.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

[Biggles]

David Hansen wrote:
On Wed, 05 Jul 2006 01:36:12 +0100 someone who may be Biggles
wrote this:-

Depends on your priorities. You don't need more than that to get a
shower you can get clean under, although you do if you want it to be
"invigorating". The greater the pressure, the more water and energy you
will use.

One will buy energy if one adds a pump. However, one will not buy
energy if using a venturi shower.

Interesting but not relevant to the point I was making. My comments were
based on the minimum head required for a gravity shower, not mains or
pumped. More head means (potentially) more flow = more energy used for a
given temperature.

Venturi showers consume more energy in exactly the same way - more flow
= more energy consumed. However, anything which avoids the use of a
pump is a good idea in my opinion, as it's one less thing to go wrong,
and you will save a bit of energy into the bargain.

Biggles