The plumbing in my bathroom seems a little unusual - the hot
is supplied via a 22mm pipe from CW tank with about 1.5m
head; the cold is mains pressure via a 15mm pipe.

I would like to keep the cold directly mains fed - but not
surprisingly, the mixer showers don't work very well.

I've thought about fitting a pressure-equalising valve
(one for the whole bathroom, rather than one per shower),
such as https://www.plumbworld.co.uk/344-0000.

Does anybody have any experience with these? Specifically,
do they need any "flow" to work?

- if the hot tap or cold tap alone is turned on, will I still get the
expected flow & pressure?

- if the cold pressure drops to zero (stopcock turned off), will
I still get any hot flow?

- I'm planning to put a double-check valve on the CW input
to the valve as well - is this necessary, or could it cause
problems?

thanks for any comments,
Andrew

"Andrew" wrote in message
...
The plumbing in my bathroom seems a little unusual - the hot
is supplied via a 22mm pipe from CW tank with about 1.5m
head; the cold is mains pressure via a 15mm pipe.

I would like to keep the cold directly mains fed - but not
surprisingly, the mixer showers don't work very well.

I've thought about fitting a pressure-equalising valve
(one for the whole bathroom, rather than one per shower),
such as https://www.plumbworld.co.uk/344-0000.

Does anybody have any experience with these? Specifically,
do they need any "flow" to work?

See the makers specs for minimum pressure and flow. They sometimes don't
operate too well when the pressure difference is too large.

- if the hot tap or cold tap alone is turned on, will I still get the
expected flow & pressure?

Yes.

- if the cold pressure drops to zero (stopcock turned off), will
I still get any hot flow?

Yes.

- I'm planning to put a double-check valve on the CW input
to the valve as well - is this necessary, or could it cause
problems?

Why?

I've thought about fitting a pressure-equalising valve
(one for the whole bathroom, rather than one per shower),
such as https://www.plumbworld.co.uk/344-0000.

Don't even think about it. Pressure equalising valves are great, but their
purpose is to put both supplies on the lowest common denominator. If one
supply is poor, it makes the other equally so. You first need to get two
good supplies.

The correct solution is to put a single impellor pump on the hot side, to
boost the hot water system to mains like pressure and flow. Then you can
worry about pressure equalising, although this will only really be
advantageous on a shower mixer, which a good model will have built in (along
with thermostatic operation).

An alternative to the pump is to fit a "venturi" type shower, which uses
energy from the cold mains to boost the hot water through the mixer. This
won't help other outlets, like the bath taps, that might also have poor
flow.

- I'm planning to put a double-check valve on the CW input
to the valve as well - is this necessary, or could it cause
problems?

It is required for hosed shower mixers unless you put one of those intensely
annoying clips on the shower hose that prevents you using the shower to
clean the bath/cubicle with.

Christian.

Christian McArdle wrote:

The correct solution is to put a single impellor pump on the hot
side, to boost the hot water system to mains like pressure and flow.

Does anyone know where you can get single impeller pumps? I've not found
any on-line and wouldn't mind getting one for our HW system in general.

--
Scott

Where are we going and why am I in this handbasket?

Does anyone know where you can get single impeller pumps? I've not found
any on-line and wouldn't mind getting one for our HW system in general.

I believe someone recently recommended the Grundfos UPA 15-90 "Home
Booster".

The other manufacturer normally recommended is the Stuart Turner. They do
quite a number of single impellor pumps, from their entry level Showermate
1.2 (around 130 quid) to a Monsoon 3.0 (around 290). Obviously, there are
twin impellor versions of these, so check carefully.

Christian.

"Christian McArdle" wrote in message
. net...
Does anyone know where you can get single impeller pumps? I've not found
any on-line and wouldn't mind getting one for our HW system in general.

I believe someone recently recommended the Grundfos UPA 15-90 "Home
Booster".

The other manufacturer normally recommended is the Stuart Turner. They do
quite a number of single impellor pumps, from their entry level Showermate
1.2 (around 130 quid) to a Monsoon 3.0 (around 290). Obviously, there are
twin impellor versions of these, so check carefully.

The Grundfoss is quite cheap. When having booster on hot and cold on the
mains, it is best to check the pressure of both. Ideally they should be
near each other. If they are then a pressure equalizing valve will trim
off.

Christian McArdle wrote:

I believe someone recently recommended the Grundfos UPA 15-90 "Home
Booster".

The other manufacturer normally recommended is the Stuart Turner. They do
quite a number of single impellor pumps, from their entry level Showermate
1.2 (around 130 quid) to a Monsoon 3.0 (around 290). Obviously, there are
twin impellor versions of these, so check carefully.

Cheers for those. I'll go and see what I can find, but can anyone
recommend somewhere that sells 'em?

--
Scott

Where are we going and why am I in this handbasket?

"Scott M" wrote in message
...
Christian McArdle wrote:

I believe someone recently recommended the Grundfos UPA 15-90 "Home
Booster".

The other manufacturer normally recommended is the Stuart Turner. They
do
quite a number of single impellor pumps, from their entry level
Showermate
1.2 (around 130 quid) to a Monsoon 3.0 (around 290). Obviously, there
are
twin impellor versions of these, so check carefully.

Cheers for those. I'll go and see what I can find, but can anyone
recommend somewhere that sells 'em?

Plumb Center for the Grudndfos.

On Thu, 21 Oct 2004 10:18:56 GMT, Scott M
wrote:

Christian McArdle wrote:

The correct solution is to put a single impellor pump on the hot
side, to boost the hot water system to mains like pressure and flow.

Does anyone know where you can get single impeller pumps? I've not found
any on-line and wouldn't mind getting one for our HW system in general.

Hi,

How about using a dual impellor with both sides in parallel?

cheers,
Pete.

"Pete C" wrote in message
...
On Thu, 21 Oct 2004 10:18:56 GMT, Scott M
wrote:

Christian McArdle wrote:

The correct solution is to put a single impellor pump on the hot
side, to boost the hot water system to mains like pressure and flow.

Does anyone know where you can get single impeller pumps? I've not found
any on-line and wouldn't mind getting one for our HW system in general.

Hi,

How about using a dual impellor with both sides in parallel?

You can't pump main water.

How about using a dual impellor with both sides in parallel?

You can't pump main water.

I think he meant to use both impellers on the hot side. However, this is
unnecessary. Single impeller pumps are widely available and cost less than
the equivalent twin impellers.

Christian.

Christian McArdle wrote:

I think he meant to use both impellers on the hot side. However, this is
unnecessary. Single impeller pumps are widely available and cost less than
the equivalent twin impellers.

Having Google'd by brand name I turned up half a dozen places selling
'em. Never realised they were that common as, although I kept hearing
about them, I'd never found any before just looking for "single
impeller", etc. And the sheds never stock such things.

--
Scott

Where are we going and why am I in this handbasket?

IMM wrote:

Plumb Center for the Grudndfos.

Ta very much. I've got one of those local, too.

--
Scott

Where are we going and why am I in this handbasket?