To explain - I've just installed a Pandora heat bank. This replaced
my previous system which had a cold water tank and how water cylinder,
with a big American pump to give me a really excellent shower.

I have to say that I'm a little disappointed with the pressure from
the cold mains. I will be getting my plumber to have a look at the
pipe runs etc, to ensure that I am getting the most from my current
system. However I suspect that i've just been spoiled by the luxure
of having a pump.

So my question is, what would happen if I put the pump back in
circuit? I'm confident that the Pandora could cope with the increased
heat demand. But would I be able to significantly increase the water
pressure? Would this have any knock-on effect for my neighbours? And
what would Thames Water say if they found out (and would they ever
find out?)

Many thanks,

Chris

Chris wrote:
snip
So my question is, what would happen if I put the pump back in
circuit? I'm confident that the Pandora could cope with the increased
heat demand. But would I be able to significantly increase the water
pressure? Would this have any knock-on effect for my neighbours? And
what would Thames Water say if they found out (and would they ever
find out?)

The basic problem is that if you reduce the pressure in the pipe
to less than atmospheric (as is quite possible to do) that you suck
surrounding water in through any leaks.

On 24 Nov 2004 13:54:10 -0800, (Chris) wrote:

To explain - I've just installed a Pandora heat bank. This replaced
my previous system which had a cold water tank and how water cylinder,
with a big American pump to give me a really excellent shower.

Oh dear.


I have to say that I'm a little disappointed with the pressure from
the cold mains. I will be getting my plumber to have a look at the
pipe runs etc, to ensure that I am getting the most from my current
system. However I suspect that i've just been spoiled by the luxure
of having a pump.

Yes.


So my question is, what would happen if I put the pump back in
circuit? I'm confident that the Pandora could cope with the increased
heat demand. But would I be able to significantly increase the water
pressure? Would this have any knock-on effect for my neighbours? And
what would Thames Water say if they found out (and would they ever
find out?)

Unfortunately it's not allowed by the water byelaws.

THe only things that you can do are to increase the pipe sizes
(perhaps back to the street), check that the stop cock is a full bore
type (change if not); and after that consider a water accumulator.
These are a pressure vessel which stores water and is filled from the
main. You can use the contents more quickly than it is filled for a
period of time - e.g. a shower.



Many thanks,

Chris


--

..andy

To email, substitute .nospam with .gl

"Ian Stirling" wrote in message
...
Chris wrote:
snip
So my question is, what would happen if I put the pump back in
circuit? I'm confident that the Pandora could cope with the increased
heat demand. But would I be able to significantly increase the water
pressure? Would this have any knock-on effect for my neighbours? And
what would Thames Water say if they found out (and would they ever
find out?)

The basic problem is that if you reduce the pressure in the pipe
to less than atmospheric (as is quite possible to do) that you suck
surrounding water in through any leaks.



I would think that the only acceptable way to pump mains sourced water is
via a storage tank - whatever the end purpose.


Pete
www.thecanalshop.com

On Wed, 24 Nov 2004 22:34:49 +0000, Andy Hall wrote:

On 24 Nov 2004 13:54:10 -0800, (Chris) wrote:

To explain - I've just installed a Pandora heat bank. This replaced my
previous system which had a cold water tank and how water cylinder, with
a big American pump to give me a really excellent shower.

Oh dear.


I have to say that I'm a little disappointed with the pressure from the
cold mains. I will be getting my plumber to have a look at the pipe runs
etc, to ensure that I am getting the most from my current system.
However I suspect that i've just been spoiled by the luxure of having a
pump.

Yes.


So my question is, what would happen if I put the pump back in circuit?
I'm confident that the Pandora could cope with the increased heat demand.
But would I be able to significantly increase the water pressure? Would
this have any knock-on effect for my neighbours? And what would Thames
Water say if they found out (and would they ever find out?)

Unfortunately it's not allowed by the water byelaws.

And probably wouldn't help much - there's only so much water you can suck
through a restricted pipe, assuming that your static mains pressure is OK.

THe only things that you can do are to increase the pipe sizes (perhaps
back to the street), check that the stop cock is a full bore type (change
if not); and after that consider a water accumulator. These are a pressure
vessel which stores water and is filled from the main. You can use the
contents more quickly than it is filled for a period of time - e.g. a
shower.


Yep. Based on my research (specifically Gledhill heat bank), it seems that
good pressure (3 bar or so) and 22mm mains are required for the
full effect with this type of system.

That's probably not unrescuable. Check your mains feed to the stopcock and
see if it's old mouldy lead/iron (either not very big or furred up to
buggery) or a decently sized bit of blue plastic. You may only need to
replace your side of the supply.

Also, best to make sure that you don't have say kitchen taps or w/machine
and shower coming off the same bit of 15mm. Should be 22 (hot and
cold) until that final split. I doubt it hurts to have the bathroom taps
and shower off the same pipe as you won't be showering and running a bath
at the same time, but other runs should be checked.

HTH

Timbo

To explain - I've just installed a Pandora heat bank. This replaced
my previous system which had a cold water tank and how water cylinder,
with a big American pump to give me a really excellent shower.

Yes, a mains pressure hot water system is totally dependent on the mains to
provide acceptable levels of pressure and flow. If these are not present,
then they won't work well.

To fix it, there are two general approaches.

1. Reinstall the cold water cistern and pump. The Pandora will just as happy
heating gravity pumped water as mains.

2. Fix the mains supply. You can only do this if the water pressure is good
enough in the street. You need to find and fix the bottleneck between the
street and your hot tap. This could be a tiny 15mm water supply from the
street, or scaled up pipework, or simply a half closed stopcock. A bit of
investigation is called for.

What is not an option is pumping the mains. This will lead to negative
pressure on the supply pipe which will cause the myriad of leaks in Thames
Water's pipework to start sucking in manky ground water rather than
squirting fresh water out.

Christian.

On 24 Nov 2004 13:54:10 -0800, (Chris) wrote:

To explain - I've just installed a Pandora heat bank. This replaced
my previous system which had a cold water tank and how water cylinder,
with a big American pump to give me a really excellent shower.

I have to say that I'm a little disappointed with the pressure from
the cold mains. I will be getting my plumber to have a look at the
pipe runs etc, to ensure that I am getting the most from my current
system. However I suspect that i've just been spoiled by the luxure
of having a pump.

So my question is, what would happen if I put the pump back in
circuit? I'm confident that the Pandora could cope with the increased
heat demand. But would I be able to significantly increase the water
pressure? Would this have any knock-on effect for my neighbours? And
what would Thames Water say if they found out (and would they ever
find out?)

Hi,

Would be worth measuring the static mains pressure at peak times, then
the pressure at the stopcock when the shower is on. This would give
the maximum possible shower pressure, and how much flow restriction
there is before the stop cock or by the stop cock itself.

If you did use a pump on the mains then it would be well worth having
a non return valve on the pump inlet to air. This would stop the mains
pressure going negative by allowing air to bleed in. Definately not an
approved way of doing things though.

I'd expect there are dedicated mains booster pumps available that have
a low pressure cutout.

cheers,
Pete.

"Pete C" wrote in message
...
On 24 Nov 2004 13:54:10 -0800, (Chris) wrote:

To explain - I've just installed a Pandora heat bank. This replaced
my previous system which had a cold water tank and how water cylinder,
with a big American pump to give me a really excellent shower.

I have to say that I'm a little disappointed with the pressure from
the cold mains. I will be getting my plumber to have a look at the
pipe runs etc, to ensure that I am getting the most from my current
system. However I suspect that i've just been spoiled by the luxure
of having a pump.

So my question is, what would happen if I put the pump back in
circuit? I'm confident that the Pandora could cope with the increased
heat demand. But would I be able to significantly increase the water
pressure? Would this have any knock-on effect for my neighbours? And
what would Thames Water say if they found out (and would they ever
find out?)

Hi,

Would be worth measuring the static mains pressure at peak times, then
the pressure at the stopcock when the shower is on. This would give
the maximum possible shower pressure, and how much flow restriction
there is before the stop cock or by the stop cock itself.

If you did use a pump on the mains then it would be well worth having
a non return valve on the pump inlet to air. This would stop the mains
pressure going negative by allowing air to bleed in. Definately not an
approved way of doing things though.

I'd expect there are dedicated mains booster pumps available that have
a low pressure cutout.

Only in exceptional circumstances will mains pumps be allowed. It will
probably be cheaper to replace the whole mains pipe back to the street and
then no pumps to make and noise, take up space and go wrong.