Rather than hijack the previous thread on these showers.

The one thing that is not made clear on the manufacturer or related
websites for venturi showers is what the *minimum* hot water
temperature should be. Has anyone any idea ? We all know what is
comfortable for us in the shower - I've just measured our's at 42 C -
but if the cold water is coming in at say 6C and has to "suck up"
sufficient hot water to raise it to that temperature, then there must
be a minimum HW temperature. OK if I measured the flow rates, etc. it
could possibly be calculated, but ...

Another thought is that the HW head / pressure is obvious, but the
mains pressure would be measured in a static situation only and will
be consistent throughout the system regardless of restrictions in the
pipework - but there must also be a flow parameter requirement.

Rob

"robgraham" wrote in message
...
Rather than hijack the previous thread on these showers.

The one thing that is not made clear on the manufacturer or related
websites for venturi showers is what the *minimum* hot water
temperature should be. Has anyone any idea ? We all know what is
comfortable for us in the shower - I've just measured our's at 42 C -
but if the cold water is coming in at say 6C and has to "suck up"
sufficient hot water to raise it to that temperature, then there must
be a minimum HW temperature. OK if I measured the flow rates, etc. it
could possibly be calculated, but ...

Another thought is that the HW head / pressure is obvious, but the
mains pressure would be measured in a static situation only and will
be consistent throughout the system regardless of restrictions in the
pipework - but there must also be a flow parameter requirement.

Rob

I've been pondering the same thoughts today as obviously a significant
amount of mixing takes place.


--


--
John

The answer would be complex, based cold water temperature, cold water
pressure and how that pressure rolls off under increasing flow, hot
water temperature (which will roll off as the store is depleted), hot
water pressure and how that pressure rolls off under increasing flow -
calculations sufficient to daunt a physicist.

In practice the manufacturers have a few graphs in the instructions -
that are likely to give satisfactory results for domestic situations.

My experience of a single example with good cold pressure and flow,
poor hot water head - was that 22mm throughout is essential - and then
results are very acceptable.

On Mon, 26 Nov 2007 07:48:05 -0800 (PST) someone who may be
robgraham wrote this:-

The one thing that is not made clear on the manufacturer or related
websites for venturi showers is what the *minimum* hot water
temperature should be.

When I investigated one thoroughly about a year ago the
manufacturer's web site had installation instructions which went
into every detail, including minimum hot water temperatures.


--
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

On 27 Nov, 08:35, David Hansen
wrote:
On Mon, 26 Nov 2007 07:48:05 -0800 (PST) someone who may be
robgraham wrote this:-

The one thing that is not made clear on the manufacturer or related
websites for venturi showers is what the *minimum* hot water
temperature should be.

When I investigated one thoroughly about a year ago the
manufacturer's web site had installation instructions which went
into every detail, including minimum hot water temperatures.

--
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

Ooops - failed to spot that ! Thanks, David. Certainly answers the
HW temperature question. The distance to the shower from the HW tank
I've emailed Trevi on to get their opinion - I suspect that based on
the graphs given and that I do have a bit more head than the minimum,
that it should be OK.

I suspect from the wording in your answer that you didn't go down this
route - why? Or alternatively if my interpretation is wrong, has it
been a success ?

Thanks

Rob

On Tue, 27 Nov 2007 02:26:17 -0800 (PST) someone who may be
robgraham wrote this:-

I suspect from the wording in your answer that you didn't go down this
route - why?

Because one doesn't need to do everything one investigates
thoroughly:-) In this particular case a thermal store had advantages
to do with the heating, it could be fitted with a shower coil to
take mains pressure water and thus a bog-standard mixer could be
used at the 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

On 27 Nov, 16:09, David Hansen
wrote:
On Tue, 27 Nov 2007 02:26:17 -0800 (PST) someone who may be
robgraham wrote this:-

I suspect from the wording in your answer that you didn't go down this
route - why?

Because one doesn't need to do everything one investigates
thoroughly:-) In this particular case a thermal store had advantages
to do with the heating, it could be fitted with a shower coil to
take mains pressure water and thus a bog-standard mixer could be
used at the 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

Thanks David
I've also done the investigation on the thermal store route and
decided the upheaval and cost doesn't really justify it, but the £200
plus for this shower and a bit of 22mm pipe work seems a better
option.

I still hanker after the thermal store but it does seem a lot of
effort and cost even on the DIY basis - having said that I haven't
come across this idea of the shower coil before and would like to
explore that further.

Rather than lose this topic in this thread, I think I will start a new
one on the shower coil subject.

Rob

"robgraham" wrote in message
...
On 27 Nov, 16:09, David Hansen
wrote:
On Tue, 27 Nov 2007 02:26:17 -0800 (PST) someone who may be
robgraham wrote this:-

I suspect from the wording in your answer that you didn't go down this
route - why?

Because one doesn't need to do everything one investigates
thoroughly:-) In this particular case a thermal store had advantages
to do with the heating, it could be fitted with a shower coil to
take mains pressure water and thus a bog-standard mixer could be
used at the 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

Thanks David
I've also done the investigation on the thermal store route and
decided the upheaval and cost doesn't really justify it, but the £200
plus for this shower and a bit of 22mm pipe work seems a better
option.

I still hanker after the thermal store but it does seem a lot of
effort and cost even on the DIY basis - having said that I haven't
come across this idea of the shower coil before and would like to
explore that further.

Rather than lose this topic in this thread, I think I will start a new
one on the shower coil subject.

Rob


You may find the cylinder needs to be 70C to run the shower, and then a
blending valve on the low pressure DHW Draw-off. Extra cost of the shower
coil is from £85 to £125 plus blending valve. But a cheaper shower mixer can
be fitted.

Or fit a plate heat exchanger and flow switch and bronze pump (may as well
go full heat bank then).

On Tue, 27 Nov 2007 09:56:34 -0800 (PST) someone who may be
robgraham wrote this:-

I've also done the investigation on the thermal store route and
decided the upheaval and cost doesn't really justify it,

The upheaval and cost just to get a mains pressure shower is not
worthwhile for most people. However, it can become worthwhile if
allows other things to be done at the same time.

I still hanker after the thermal store but it does seem a lot of
effort and cost even on the DIY basis

The effort depends on the changes one is making. I was making a
number of changes and thus the effort was higher than just slapping
one in.

The cursing, swearing and scratches/bruises were largely due to the
changes I was making to the pipework, one of the few exceptions
being when a joint I had not done up properly came apart in my hands
and a stream of water at 65C, under a head of nearly 10m, hit me in
the chest:-(

As for the cost, it is nothing compared to what some/many spend on a
kitchen, car, television and so on.

http://www.navitron.org.uk/pricelist.htm indicates a premium of £320
for a thermal store coil and £125 for a shower coil. The shower coil
could be fitted in a conventional vented hot water cylinder should
one not wish to have a thermal store.

Rather than lose this topic in this thread, I think I will start a new
one on the shower coil subject.

If I spot one I will join it if I have anything extra to say.


--
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

"David Hansen" wrote in message
...
On Tue, 27 Nov 2007 02:26:17 -0800 (PST) someone who may be
robgraham wrote this:-

I suspect from the wording in your answer that you didn't go down this
route - why?

Because one doesn't need to do everything one investigates
thoroughly:-) In this particular case a thermal store had advantages
to do with the heating, it could be fitted with a shower coil to
take mains pressure water and thus a bog-standard mixer could be
used at the 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

also:
http://www.copperform.co.uk/mains_pr...ower/index.htm