Pressure Balanced Pex Home Run Manifold?

[DerbyDad03]

I was watching one of the varieties of the Holmes On The Range shows. Mike
was literally gushing over the Pex home run manifold that had been
installed by his plumber. I gotta admit, it was pretty nice looking. Each
curved run of Pex was perfectly spaced, with a long, sweeping, graceful
layout. Multiple runs went off to the left and the right, laid out
perfectly like a pair of angel's wings. :-)

Anyway, Mike repeated multiple times, each time with more passion, that the
system was "pressure balanced", saying that that means "if you are taking a
shower upstairs and someone flushes a toilet downstairs, the pressure in
the shower won't change."

He wasn't talking about a pressure balanced shower valve or consistent
temperatures. He specifically said the "pressure will never change."

OK, so how does that work? If multiple fixtures are opened, doesn't the
pressure in the system have to drop? It seems to me that the only way for
the pressure to never change as each additional fixture is opened is to
have the system running at some specific pressure when only one fixture is
open and then have it boosted each time another fixture is opened. After
all, you can only have so much pressure in the building to begin with -
street pressure - unless you boost it with a holding tank and a pump. There
was no mention of anything like that being installed.

What am I missing?

[Bob F]

My best guess.

If there is a large pipe going to the manifold, and small PEX coming off it,
each to a different fixture (with low volume faucets), the pressure should stay
pretty much the same even when multiple faucets are run. Pressure drop occur
when large volumes are sent through too small of a pipe.

[Nightcrawler®]

"Bob F" <bobn...@gmail.com> wrote in message news:l648lt$t8q$1...@dont-email.me...

>
> My best guess.
>
> If there is a large pipe going to the manifold, and small PEX coming off it,
> each to a different fixture (with low volume faucets), the pressure should stay
> pretty much the same even when multiple faucets are run. Pressure drop occur
> when large volumes are sent through too small of a pipe.
>
>

Many people confuse pressure with flow. Pressure is rather irrelevant
in most cases. It is the flow that really matters. By supplying smaller
laterals with a large volume of water (larger diameter pipe), each circuit
will be able to maintain its maximum flow.

Picture a barrel filled with water. Drill a 1/4" hole at the base. Notice
the stream of water coming out. This is that holes maximum flow at the
supplied pressure/head water provided. Now, drill five more holes. You
will not notice a difference in flow. Drill five more and you still would
not notice a change. The secret is figuring out what the optimal dia. of the
manifold should be for a common load on the system. Say, shower, toilet, and
possibly a faucet running at the same time. Of course, the max manifold dia.
is set by the main dia. Usually 7/8" I.D.

[Vic Smith]

On Fri, 15 Nov 2013 02:36:53 +0000 (UTC), DerbyDad03
<teama...@eznet.net> wrote:

>I was watching one of the varieties of the Holmes On The Range shows. Mike
>was literally gushing over the Pex home run manifold that had been
>installed by his plumber. I gotta admit, it was pretty nice looking. Each
>curved run of Pex was perfectly spaced, with a long, sweeping, graceful
>layout. Multiple runs went off to the left and the right, laid out
>perfectly like a pair of angel's wings. :-)
>
>Anyway, Mike repeated multiple times, each time with more passion, that the
>system was "pressure balanced", saying that that means "if you are taking a
>shower upstairs and someone flushes a toilet downstairs, the pressure in
>the shower won't change."
>
>He wasn't talking about a pressure balanced shower valve or consistent
>temperatures. He specifically said the "pressure will never change."
>

That's what they say about pressure balanced shower valves. Some
places require them in new homes by code.
They basically normally restrict total flow of hot and cold combined,
then adjust to whichever side loses pressure. to prevent scalding or a
dose of cold water.
So since total flow was restricted initially, the actual pressure at
the shower nozzle head won't change when the valve allows more hot or
cold flow.
Actual pressure in the supply piping will always change with different
flow rates.
Semantic razzle dazzle, since if cold water flow is interrupted in
those valves, they shut down. What kind of pressure is that?
And some might be designed differently than I've said. I just made it
up.
This guy seems to know about them.
http://ths.gardenweb.com/forums/load/bath/msg112139239337.html

He says they start with 100% flow, then choke down on one side or the
other when their pressure is out of balance.
Of course that reduces pressure at the shower head,
I like my way better.

[tra...@optonline.net]

That would be my guess too, unless it's some kind of special
manifold. I think the worst pressure drop problems occur with
traditional plumbing when you have multiple places served by the
same run, like two bathrooms. If you have homeruns to the two
from the central manifold, the pressure/flow is going to stay more
constant and any change would be less noticeable.

[DerbyDad03]

The copper pipes used for the manifold were indeed fairly large. Hard to
say from just watching the show, but 3/4" - 7/8" is what they looked like.

[Wes Groleau]

On 11-14-2013, 23:41, Bob F wrote:
> If there is a large pipe going to the manifold, and small PEX coming off it,
> each to a different fixture (with low volume faucets), the pressure should stay
> pretty much the same even when multiple faucets are run. Pressure drop occur
> when large volumes are sent through too small of a pipe.

Actually, a pressure drop occurs in a smaller pipe when _attempting_ to
get more volume than the pipe can handle AND when another pipe relieves
the pressure.

If you really want constant pressure exactly (not merely "pretty much")
have a source offering more than all fixtures can use and put a
regulator on each. :-)

--
Wes Groleau

A pessimist says the glass is half empty.
An optimist says the glass is half full.
An engineer says somebody made the glass
twice as big as it needed to be.

[Wes Groleau]

On 11-15-2013, 01:39, Nightcrawler® wrote:
> Many people confuse pressure with flow. Pressure is rather irrelevant
> in most cases. It is the flow that really matters. By supplying smaller

Except when you want a shower that helps you scrub
instead of merely getting you wet. :-)

--
Wes Groleau

“There are more people worthy of blame
than there is blame to go around."

[Oren]

On Thu, 14 Nov 2013 20:41:05 -0800, "Bob F" <bobn...@gmail.com>
wrote:

>If there is a large pipe going to the manifold, and small PEX coming off it,
>each to a different fixture (with low volume faucets), the pressure should stay
>pretty much the same even when multiple faucets are run. Pressure drop occur
>when large volumes are sent through too small of a pipe.

<snipped from the net> "...parallel system provides the lowest
pressure and temperature fluctuations in a plumbing system. Since each
tubing line is dedicated to an individual fixture, interference
between fixtures is eliminated. Additionally, specific fixtures can be
supplied by smaller diameter tubing depending on the actual amount of
water needed. "

Pic:

<http://www.viega.net/cps/rde/xbcr/en-us/MANABLOC_new_lg.jpg>

The hot water is in a "continuously recirculating domestic hot water
plumbing loops".... page 16

<http://www.abouthomes.info/files/0525%206518.pdf>

[Arthur Conan Doyle]

Wes Groleau <Grolea...@FreeShell.org> wrote:

>Actually, a pressure drop occurs in a smaller pipe when _attempting_ to
>get more volume than the pipe can handle AND when another pipe relieves
>the pressure.

The classic problem is a scalding shower when someone flushes a nearby toilet.
That happens because the shower is using a blend of cold and hot water and the
toilet is attempting to draw cold water from the same 1/2" supply line that
feeds the shower. Hence a reduction in cold water to the shower.

By home running lines back to a manifold, the house supply is theoretically
enough to handle both fixtures, and if it isn't, it will reduce the hot side
equally to compensate.

[k...@attt.bizz]

On Fri, 15 Nov 2013 02:36:53 +0000 (UTC), DerbyDad03
<teama...@eznet.net> wrote:

It's not "balanced", rather since the runs are all "home runs", there
is no pressure drop because one branch turns on. This is true, of
course, only of the size of the feed can accommodate the sum of the
loads. This is also true of multi-drop runs. If you increase the size
of the branch at each tap, it works the same way.

The down-side of the home-run strategy is that you can't use one tap
to "pre-heat" (or cool) water for another. There is no way to
"pre-heat" the water for the dishwasher, for instance. It *will* get
cold water to start.

[k...@attt.bizz]

On Fri, 15 Nov 2013 12:11:25 -0500, Wes Groleau
<Grolea...@FreeShell.org> wrote:

>On 11-15-2013, 01:39, Nightcrawler� wrote:
>> Many people confuse pressure with flow. Pressure is rather irrelevant
>> in most cases. It is the flow that really matters. By supplying smaller
>
>Except when you want a shower that helps you scrub
>instead of merely getting you wet. :-)

Or actually want to get the soap out of your hair. ;-) There are
many cases where pressure is more important than flow rate. Both are
important.

[Nightcrawler®]

"Wes Groleau" <Grolea...@FreeShell.org> wrote in message news:l65kjt$1k0$1...@dont-email.me...

LOL!

Well, if you can keep the manifold pressure above 40 psi,
and you have a good shower head, I do not foresee a problem.
Reducing the dia. of the laterals also increases the velocity
of the water coming out of head/tap. Of course, if one is
desperate, they may hook up a power washer, in series, and
get an awesome rinse. :-)

[Wes Groleau]

Speaking of showers, any one beside me irritated at the fact that the
distance between the tub and shower head in most hotels is LESS than the
height of the average adult male?

--
Wes Groleau

“It is incumbent on every generation to pay its own debts as it
goes. A principle which if acted on would save one-half the wars of the
world.”
— Thomas Jefferson

[sms]

On 11/15/2013 10:14 PM, Wes Groleau wrote:
> On 11-15-2013, 20:07, k...@attt.bizz wrote:
>> On Fri, 15 Nov 2013 12:11:25 -0500, Wes Groleau
>> <Grolea...@FreeShell.org> wrote:
>>> On 11-15-2013, 01:39, Nightcrawler® wrote:
>>>> Many people confuse pressure with flow. Pressure is rather irrelevant
>>>> in most cases. It is the flow that really matters. By supplying
>>>> smaller
>>>
>>> Except when you want a shower that helps you scrub
>>> instead of merely getting you wet. :-)
>>
>> Or actually want to get the soap out of your hair. ;-) There are
>> many cases where pressure is more important than flow rate. Both are
>> important.
>
> Speaking of showers, any one beside me irritated at the fact that the
> distance between the tub and shower head in most hotels is LESS than the
> height of the average adult male?

Many houses have that same issue. I think it's because someone wants to
save money buy having shower walls that don't go up to the ceiling.

When we remodeled our bathrooms I had them move the shower heads up to a
reasonable height.

I remember renting a house up at Lake Tahoe. I rented the same house
fairly often and I began bringing by own shower heads. I would change to
regular flow while I was there then put back the low flow when I left. I
simply realized that arguing with the owner about this would have no
effect and that I had to work around the problem. And since every
property that's rented out likely has the same issue, it would not have
helped to get upset about it and not rent that place any more.

[Stormin Mormon]

On 11/16/2013 1:14 AM, Wes Groleau wrote:
>
> Speaking of showers, any one beside me irritated at the fact that the
> distance between the tub and shower head in most hotels is LESS than the
> height of the average adult male?
>

Worse, the shower heads typically deliver about 0.001 GPM.

--
.
Christopher A. Young
Learn about Jesus
www.lds.org
.

[Stormin Mormon]

On 11/16/2013 1:29 AM, sms wrote:
>
> I remember renting a house up at Lake Tahoe. I rented the same house
> fairly often and I began bringing by own shower heads. I would change to
> regular flow while I was there then put back the low flow when I left. I
> simply realized that arguing with the owner about this would have no
> effect and that I had to work around the problem. And since every
> property that's rented out likely has the same issue, it would not have
> helped to get upset about it and not rent that place any more.
>

I've been tempted to travel with a shower head and
pipe wrench, for just that reason. Glad someone else
has already done so.

[k...@attt.bizz]

On Sat, 16 Nov 2013 01:14:39 -0500, Wes Groleau

<Grolea...@FreeShell.org> wrote:

>On 11-15-2013, 20:07, k...@attt.bizz wrote:
>> On Fri, 15 Nov 2013 12:11:25 -0500, Wes Groleau
>> <Grolea...@FreeShell.org> wrote:
>>> On 11-15-2013, 01:39, Nightcrawler� wrote:
>>>> Many people confuse pressure with flow. Pressure is rather irrelevant
>>>> in most cases. It is the flow that really matters. By supplying smaller
>>>
>>> Except when you want a shower that helps you scrub
>>> instead of merely getting you wet. :-)
>>
>> Or actually want to get the soap out of your hair. ;-) There are
>> many cases where pressure is more important than flow rate. Both are
>> important.
>
>Speaking of showers, any one beside me irritated at the fact that the
>distance between the tub and shower head in most hotels is LESS than the
>height of the average adult male?

The shower in one of hotels I stayed in recently (don't remember
which, now) had a step-up bathtub. The floor of the tub was a foot
above the floor. Not only was the shower head below my head but so
was the ceiling.

[Doug Miller]

Wes Groleau <Grolea...@FreeShell.org> wrote in news:l672ge$g81$2...@dont-email.me:

> Speaking of showers, any one beside me irritated at the fact that the
> distance between the tub and shower head in most hotels is LESS than the
> height of the average adult male?

That's one of my major pet peeves -- seems to me that, at five-nine, I should *never* encounter
a showerhead that's too low. And yet, in almost every hotel room I've ever been in...

[Nightcrawler®]

"Doug Miller" <doug_at_mil...@example.com> wrote in message news:XnsA27AA9EC9F4...@78.46.70.116...

While the spray feels good on my chest, I hate having to bend over to rinse
my head. I like my shower heads at a minimum of 6'8". This takes a bit of
modification (a three way valve and one of those long, flex shower heads),
but is worth it in the long run.

[k...@attt.bizz]

I like the shower in our other house. It's a rain head on a 9'
ceiling. When I redo the bathroom here, I'll do the same. I'll add a
flexible head, as well (for cleaning).

[Nightcrawler®]

<k...@attt.bizz> wrote in message news:cfvf89dq8mefjb0vu...@4ax.com...

> On Sat, 16 Nov 2013 16:31:56 -0600, Nightcrawler�

<snip>

>
> I like the shower in our other house. It's a rain head on a 9'
> ceiling. When I redo the bathroom here, I'll do the same. I'll add a
> flexible head, as well (for cleaning).

Sounds awesome.

I have a friend that did a whole house renovation. He added a
Jacuzzi tub and turned a regular shower into a 5x5 walk in that
essentially was a car wash. I laughed and said, "boy, you are
lazy!" Just envy speaking, of course. :-)

[John Albert]

On 11/16/13 6:48 AM, Stormin Mormon wrote:
>
> Worse, the shower heads typically deliver about 0.001 GPM.

Just wondering -- what's the GPM rating for PEX (the size
that is generally used for runs to the bathroom)?

Is it 4gpm?
Is it 6gpm?
is it 10gpm?
What is it?

[Oren]

On Sat, 16 Nov 2013 23:55:51 -0500, John Albert <j.al...@snet.net>
wrote:

Chart:

(1) BASED ON 2 FT/SEC
(2) BASED ON 4 FT/SEC

<http://s3.pexsupply.com/manuals/1322593642270/68976_PROD_FILE.pdf>

[Caulki...@work.com]

On Fri, 15 Nov 2013 12:11:25 -0500, Wes Groleau
<Grolea...@FreeShell.org> wrote:

>Except when you want a shower that helps you scrub
>instead of merely getting you wet. :-)
>

That's what women are for! :)

[k...@attt.bizz]

The shower in that house is 6'x6'. I loved it. I want to do similar
here but have to get the mortgage paid first (and the other house
closed).

I was at my cousin's new house this last summer. Theirs was big
enough and set up such that no doors were necessary. *Really* nice.
I'm going to see if I have the space to do it here. I may have to
move the Jacuzzi tub (which never gets used), though.

[Ashton Crusher]

On Sat, 16 Nov 2013 06:48:15 -0500, Stormin Mormon
<cayo...@hotmail.com> wrote:

>On 11/16/2013 1:14 AM, Wes Groleau wrote:
>>
>> Speaking of showers, any one beside me irritated at the fact that the
>> distance between the tub and shower head in most hotels is LESS than the
>> height of the average adult male?
>>
>
>Worse, the shower heads typically deliver about 0.001 GPM.

The worst I've ever experienced in a hotel was a combination of a low
flow head with an aerator. So all you got was foaming warm, not hot
(because the air cooled the water down so much) water. So to get it
warm enough you had to turn it to almost all hot water, almost no
cold. SO their stupid aerator cost them more in heating the water
then it saved in water I would guess.