Hello,

When taps are described as suitable for high water pressure or low
water pressure, or reducers in toilet inlets, etc. what is the
definition of high pressure and low pressure, i.e. how many bars does
it have to be to be considered high pressure?

Thanks,
Stephen

On 22/03/2014 17:57, Stephen wrote:
Hello,

When taps are described as suitable for high water pressure or low
water pressure, or reducers in toilet inlets, etc. what is the
definition of high pressure and low pressure, i.e. how many bars does
it have to be to be considered high pressure?

Thanks,
Stephen

As a rule of fumb, I believe they refer to mains as 'high' and gravity
as 'low'.


--
Dave - The Medway Handyman www.medwayhandyman.co.uk

On 22/03/2014 18:11, The Medway Handyman wrote:
On 22/03/2014 17:57, Stephen wrote:
Hello,

When taps are described as suitable for high water pressure or low
water pressure, or reducers in toilet inlets, etc. what is the
definition of high pressure and low pressure, i.e. how many bars does
it have to be to be considered high pressure?

Thanks,
Stephen

As a rule of fumb, I believe they refer to mains as 'high' and gravity
as 'low'.

I would say that anything over 1 bar counts as high.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

In article ,
says...

On 22/03/2014 18:11, The Medway Handyman wrote:
On 22/03/2014 17:57, Stephen wrote:
Hello,

When taps are described as suitable for high water pressure or low
water pressure, or reducers in toilet inlets, etc. what is the
definition of high pressure and low pressure, i.e. how many bars does
it have to be to be considered high pressure?

Thanks,
Stephen

As a rule of fumb, I believe they refer to mains as 'high' and gravity
as 'low'.

I would say that anything over 1 bar counts as high.

Relative, or absolute?

--
Sam

On 22/03/2014 23:36, Sam Plusnet wrote:
In article ,
says...

On 22/03/2014 18:11, The Medway Handyman wrote:
On 22/03/2014 17:57, Stephen wrote:
Hello,

When taps are described as suitable for high water pressure or low
water pressure, or reducers in toilet inlets, etc. what is the
definition of high pressure and low pressure, i.e. how many bars does
it have to be to be considered high pressure?

Thanks,
Stephen

As a rule of fumb, I believe they refer to mains as 'high' and gravity
as 'low'.

I would say that anything over 1 bar counts as high.

Relative, or absolute?

above atmospheric...


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Sat, 22 Mar 2014 18:11:04 +0000, The Medway Handyman
wrote:

As a rule of fumb, I believe they refer to mains as 'high' and gravity
as 'low'.

But what happens when you have a mixer tap which is fed by gravity hot
water but mains cold?

In article ,
Stephen wrote:
On Sat, 22 Mar 2014 18:11:04 +0000, The Medway Handyman
wrote:

As a rule of fumb, I believe they refer to mains as 'high' and gravity
as 'low'.

But what happens when you have a mixer tap which is fed by gravity hot
water but mains cold?

my kitchen tap works fine.

--
From KT24

Using a RISC OS computer running v5.18

On 23/03/2014 20:58, Stephen wrote:
On Sat, 22 Mar 2014 18:11:04 +0000, The Medway Handyman
wrote:

As a rule of fumb, I believe they refer to mains as 'high' and gravity
as 'low'.

But what happens when you have a mixer tap which is fed by gravity hot
water but mains cold?


If its a good one, not a lot as they don't mix until the outlet.
If its a rubbish one then the high pressure cold forces the hot water
back into the tank and it overflows.

On 23/03/2014 20:58, Stephen wrote:
On Sat, 22 Mar 2014 18:11:04 +0000, The Medway Handyman
wrote:

As a rule of fumb, I believe they refer to mains as 'high' and gravity
as 'low'.

But what happens when you have a mixer tap which is fed by gravity hot
water but mains cold?

If its a proper mixer tap then the cold feed must include a double check
valve...

Having said that - they often don't work well in this setup - in some
cases just forcing mains cold back up the hot feed!

(typical kitchen mixers are of a concentric spout design where the
mixing (such as it is) happens outside the tap.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Sun, 23 Mar 2014 22:26:19 +0000, John Rumm
wrote:

On 23/03/2014 20:58, Stephen wrote:
On Sat, 22 Mar 2014 18:11:04 +0000, The Medway Handyman
wrote:

As a rule of fumb, I believe they refer to mains as 'high' and gravity
as 'low'.

But what happens when you have a mixer tap which is fed by gravity hot
water but mains cold?

If its a proper mixer tap then the cold feed must include a double check
valve...

Having said that - they often don't work well in this setup - in some
cases just forcing mains cold back up the hot feed!

(typical kitchen mixers are of a concentric spout design where the
mixing (such as it is) happens outside the tap.

Bath mixer taps with shower diverter valve aren't meant to be fed
direct from the rising main (ditto for shower mixers). The cold is
meant to be fed off the header tank to maintain equal pressure between
the hot and cold supplies.

Kitchen 'mixer taps' designed to allow a direct rising main feed for
drinking water usage keep the two streams seperate until they emerge
from the 'mixer nozzle' specifically to avoid this back flushing
issue.

However, it is possible to defeat this simple protection against
unintended backflushing by forcing an old fashioned push on washing
machine hose over the end of the mixer nozzle outlet as I proved when
the flow from the hot tap had dropped to a slow trickle a few months
after the kitchen extension had been built.

In this case, the backflushing was an intended result which
completely restored the hot flow to better than new where it has
remained so for the past 28 years since.

The central heating developed a blockage in the header tank feed a
year or so after it had been installed which prevented me from
bleeding air out of even the ground floor radiators. Obviously a
serious issue which I tackled by pushing a suitable length of pyro
cable down the feed pipe from the header tank until it hit and broke
the obstruction right at the soldered T joint.

It seemed to me that I must have broken up an encrustation that had
formed across the end of the feed pipe just where it met the
horizontal run of the CH pipework. Like the kitchen hot water feed,
this also proved to be a permanent fix.

In this case, I assumed that dissolved residues from the soldering
had precipitated out just where the hot water met the cold header tank
feed and had built up a crust across the end until it had completely
sealed the cold 'port' at the T joint.

In the case of the ever reducing kitchen tap hot water flow, I'd
assumed a concentration of soldering debris building up at a sharp
bend/ T joint connection which I'd managed to dislodge by my pulsing
the backflush pressure (although ther hadn't been any obvious signs of
'crud' appearing during this process).

At the time, there was no access to information via a search engine
as there is today so I never pursued my theories on this 'strange' (to
me) phenomena nor ask if this was a fairly common issue with brand new
plumbing works.

I do harbour a suspicion that this might have been the result of
'deliberate' sabotage in order to screw extra payment out of post
installation work that should have been carried out as part of a
'proper job'. Is there a possibilty of my suspicions having some basis
in fact or was I simply being paranoid?
--
Regards, J B Good

On 24/03/2014 02:53, Johny B Good wrote:
On Sun, 23 Mar 2014 22:26:19 +0000, John Rumm
wrote:

On 23/03/2014 20:58, Stephen wrote:
On Sat, 22 Mar 2014 18:11:04 +0000, The Medway Handyman
wrote:

As a rule of fumb, I believe they refer to mains as 'high' and gravity
as 'low'.

But what happens when you have a mixer tap which is fed by gravity hot
water but mains cold?

If its a proper mixer tap then the cold feed must include a double check
valve...

Having said that - they often don't work well in this setup - in some
cases just forcing mains cold back up the hot feed!

(typical kitchen mixers are of a concentric spout design where the
mixing (such as it is) happens outside the tap.

Bath mixer taps with shower diverter valve aren't meant to be fed
direct from the rising main (ditto for shower mixers). The cold is
meant to be fed off the header tank to maintain equal pressure between
the hot and cold supplies.

Assuming that the hot supply is low pressure. When fed from a combi for
example it would be normal to supply the tap from the rising main (via a
double check).

If fed from an unvented cylinder, the the cold ought to be fed from the
pressure balanced output of the PRV.

Kitchen 'mixer taps' designed to allow a direct rising main feed for
drinking water usage keep the two streams seperate until they emerge
from the 'mixer nozzle' specifically to avoid this back flushing
issue.

However, it is possible to defeat this simple protection against
unintended backflushing by forcing an old fashioned push on washing
machine hose over the end of the mixer nozzle outlet as I proved when
the flow from the hot tap had dropped to a slow trickle a few months
after the kitchen extension had been built.

In this case, the backflushing was an intended result which
completely restored the hot flow to better than new where it has
remained so for the past 28 years since.

Forcing mains cold up a vented hot feed is a "standard" trick for
clearing an air lock in the hot feed.

The central heating developed a blockage in the header tank feed a
year or so after it had been installed which prevented me from
bleeding air out of even the ground floor radiators. Obviously a
serious issue which I tackled by pushing a suitable length of pyro
cable down the feed pipe from the header tank until it hit and broke
the obstruction right at the soldered T joint.

It seemed to me that I must have broken up an encrustation that had
formed across the end of the feed pipe just where it met the
horizontal run of the CH pipework. Like the kitchen hot water feed,
this also proved to be a permanent fix.

In this case, I assumed that dissolved residues from the soldering
had precipitated out just where the hot water met the cold header tank
feed and had built up a crust across the end until it had completely
sealed the cold 'port' at the T joint.

Remember its not just a feed tank though, but feed and expansion. So in
normal use, hot water will push up into the F&E tank. Its probably the
place where you get most heating and cooling cycles of the water,
coupled with the location where most new (i.e. oxygenated) water will
enter the system, so its a prime location for a scale related blockage.
(not to mention any other fungal growth that decides to form a crust
over the top of the nice bacterium friendly warm water tank!)

In the case of the ever reducing kitchen tap hot water flow, I'd
assumed a concentration of soldering debris building up at a sharp
bend/ T joint connection which I'd managed to dislodge by my pulsing
the backflush pressure (although ther hadn't been any obvious signs of
'crud' appearing during this process).

At the time, there was no access to information via a search engine
as there is today so I never pursued my theories on this 'strange' (to
me) phenomena nor ask if this was a fairly common issue with brand new
plumbing works.

Air locks in gravity fed HW systems are quite common unless the
installer has taken great care with all the pipe runs to make sure there
are no inversions or up hill sections.

I do harbour a suspicion that this might have been the result of
'deliberate' sabotage in order to screw extra payment out of post
installation work that should have been carried out as part of a
'proper job'. Is there a possibilty of my suspicions having some basis
in fact or was I simply being paranoid?

Who knows... could equally be a result of less than perfectly skilled
plumbing. Never put down to malice what can be explained by incompetence
etc!



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 23/03/2014 20:58, Stephen wrote:
On Sat, 22 Mar 2014 18:11:04 +0000, The Medway Handyman
wrote:

As a rule of fumb, I believe they refer to mains as 'high' and gravity
as 'low'.

But what happens when you have a mixer tap which is fed by gravity hot
water but mains cold?


In the kitchen, I have a ball valve restrictor in the cold supply.

--
Michael Chare

On 23/03/2014 20:58, Stephen wrote:
On Sat, 22 Mar 2014 18:11:04 +0000, The Medway Handyman
wrote:

As a rule of fumb, I believe they refer to mains as 'high' and gravity
as 'low'.

But what happens when you have a mixer tap which is fed by gravity hot
water but mains cold?


(Opens new can of worms).

Many of the cheap el crappo taps sold by the sheds are designed for
mains hot & cold from a combi boiler.

If you fit one to a mains cold, gravity hot system you will only get a
trickle out of the hot side.

A 'proper' mixer, from a plumbers merchant, is designed for mains cold,
gravity hot & will work a treat.

A proper plumbers merchant will ask the punter the right questions.


--
Dave - The Medway Handyman www.medwayhandyman.co.uk

In message , The Medway Handyman
writes
On 23/03/2014 20:58, Stephen wrote:
On Sat, 22 Mar 2014 18:11:04 +0000, The Medway Handyman
wrote:

As a rule of fumb, I believe they refer to mains as 'high' and gravity
as 'low'.

But what happens when you have a mixer tap which is fed by gravity hot
water but mains cold?


(Opens new can of worms).

Many of the cheap el crappo taps sold by the sheds are designed for
mains hot & cold from a combi boiler.

If you fit one to a mains cold, gravity hot system you will only get a
trickle out of the hot side.

A 'proper' mixer, from a plumbers merchant, is designed for mains cold,
gravity hot & will work a treat.

A proper plumbers merchant will ask the punter the right questions.



Still seems to apply to some kitchen mixers, but I did notice, when
sourcing taps for the new bathroom that bathroom mixers nearly all seem
to be balanced pressure (or unspecified) nowadays.

When I did the bathroom in the old house, circa 2000 the catalogues seem
to often list version for both balanced and unbalanced pressures
--
Chris French

On Mon, 24 Mar 2014 23:27:51 +0000, chris French
wrote:

Still seems to apply to some kitchen mixers, but I did notice, when
sourcing taps for the new bathroom that bathroom mixers nearly all seem
to be balanced pressure (or unspecified) nowadays.

Perhaps the fact that modern designs are unspecified means that it
doesn't matter and there's nothing for me to worry about any more?

Thanks for all the replies. The tap in question was in situ, and I
hadn't bought it. I contacted the manufacturer (ideal standard) and
they told me they define low pressure as 1 bar and anything above that
as high pressure, so I take that to mean gravity HW is low pressure
and the cold main is high pressure.

I've only ever had vented HW, so don't know about other systems. I
guess HW from a combi boiler classes as high pressure because it comes
from the mains. I know there's often concern here about combis not
being good enough for showers but I'm guessing that's low flow rather
than low pressure? Is the hot water pressure at the tap comparable to
the mains cold pressure?

BTW what flow do you need from a combi for a good shower?

Thanks,
Stephen.