I'm going to run a water line out to a little outbuilding I have out
near the barn. The line I am going to tap off of is probably a 3/4"
line. If I run a larger diameter, say a 1 or 11/4 inch from there to
the outbuilding would that result in any increase in pressure at the
outbuilding or would the fact that there was a 3/4" feed negate any
increase?
--
Careful how you respond. I have people!

JC

The Post Quartermaster wrote the following:
I'm going to run a water line out to a little outbuilding I have out
near the barn. The line I am going to tap off of is probably a 3/4"
line. If I run a larger diameter, say a 1 or 11/4 inch from there to
the outbuilding would that result in any increase in pressure at the
outbuilding or would the fact that there was a 3/4" feed negate any
increase?

If you want pressure, you go from large to small.

--

Bill
In Hamptonburgh, NY
In the original Orange County. Est. 1683
To email, remove the double zeroes after @

The Post Quartermaster wrote:
I'm going to run a water line out to a little outbuilding I have out
near the barn. The line I am going to tap off of is probably a 3/4"
line. If I run a larger diameter, say a 1 or 11/4 inch from there to the
outbuilding would that result in any increase in pressure at the
outbuilding or would the fact that there was a 3/4" feed negate any
increase?

Larger will reduce the pressure drop would otherwise have. Neither will
increase pressure above supply--it only drops, never goes up.

How long a run?

--

On Tue, 10 Aug 2010 16:50:40 -0500, "The Post Quartermaster"
wrote:

I'm going to run a water line out to a little outbuilding I have out
near the barn. The line I am going to tap off of is probably a 3/4"
line. If I run a larger diameter, say a 1 or 11/4 inch from there to
the outbuilding would that result in any increase in pressure at the
outbuilding or would the fact that there was a 3/4" feed negate any
increase?

If the valve on the spigot or outlet you'l be using has a greater
diameter than the one on the 3/4" pipe, you'll have LESS pressure.
There is no way to get more in pounds per square inch than the 3/4
has.

Also the extra length of pipe lowers the pressure some, but not very
much, maybe not even noticeable. Using larger diameter pipe will make
the effect of that less, but maybe not noticeably.

How long will the pipe be and why do you need more pressure?

"mm" wrote in message
...
On Tue, 10 Aug 2010 16:50:40 -0500, "The Post Quartermaster"
wrote:

I'm going to run a water line out to a little outbuilding I have out
near the barn. The line I am going to tap off of is probably a 3/4"
line. If I run a larger diameter, say a 1 or 11/4 inch from there to
the outbuilding would that result in any increase in pressure at the
outbuilding or would the fact that there was a 3/4" feed negate any
increase?

If the valve on the spigot or outlet you'l be using has a greater
diameter than the one on the 3/4" pipe, you'll have LESS pressure.
There is no way to get more in pounds per square inch than the 3/4
has.

Also the extra length of pipe lowers the pressure some, but not very
much, maybe not even noticeable. Using larger diameter pipe will
make
the effect of that less, but maybe not noticeably.

How long will the pipe be and why do you need more pressure?

It's only about 40 feet, if that. The place we bought has 3/4 all the
way from the well to the old house, about 125 feet. The pressure is
okay, I just thought I might lose some by extending it. I'm probably
going to upgrade all the pipe in a year or so after I get some of the
really necessary things done. Like a place to actually put a bed to
sleep on, and things like that. G They told us it was a 150 year old
farmhouse. Well, really it's a 150 year old woodpile.
--
Careful how you respond. I have people!

JC

The Post Quartermaster wrote:
I'm going to run a water line out to a little outbuilding I have out
near the barn. The line I am going to tap off of is probably a 3/4"
line. If I run a larger diameter, say a 1 or 11/4 inch from there to
the outbuilding would that result in any increase in pressure at the
outbuilding or would the fact that there was a 3/4" feed negate any
increase?

The larger diameter will reduce the additional losses added by the longer pipe,
compared to the same added length of smaller diameter pipe. The larger pipe will
also mean that a large valve at the end of the added pipe can cause a larger
pressure drop to be seen inside the house where the new pipe attaches compared
to a smaller pipe.

"dpb" wrote in message
...
The Post Quartermaster wrote:
I'm going to run a water line out to a little outbuilding I have
out near the barn. The line I am going to tap off of is probably a
3/4" line. If I run a larger diameter, say a 1 or 11/4 inch from
there to the outbuilding would that result in any increase in
pressure at the outbuilding or would the fact that there was a 3/4"
feed negate any increase?

Larger will reduce the pressure drop would otherwise have. Neither
will increase pressure above supply--it only drops, never goes up.

How long a run?

--

40 feet maybe. I just dug a two foot deep trench by hand so it feels
like it was a couple of hundred feet. And the thermometer is showing
102 in the shade.

On Tue, 10 Aug 2010 17:28:07 -0500, "The Post Quartermaster"
wrote:


"dpb" wrote in message
...
The Post Quartermaster wrote:
I'm going to run a water line out to a little outbuilding I have
out near the barn. The line I am going to tap off of is probably a
3/4" line. If I run a larger diameter, say a 1 or 11/4 inch from
there to the outbuilding would that result in any increase in
pressure at the outbuilding or would the fact that there was a 3/4"
feed negate any increase?

Larger will reduce the pressure drop would otherwise have. Neither
will increase pressure above supply--it only drops, never goes up.

How long a run?

--

40 feet maybe. I just dug a two foot deep trench by hand so it feels
like it was a couple of hundred feet. And the thermometer is showing
102 in the shade.

But you weren't in the shade all the time, so you should be okay.

On 8/10/2010 4:50 PM, The Post Quartermaster wrote:
I'm going to run a water line out to a little outbuilding I have out
near the barn. The line I am going to tap off of is probably a 3/4"
line. If I run a larger diameter, say a 1 or 11/4 inch from there to the
outbuilding would that result in any increase in pressure at the
outbuilding or would the fact that there was a 3/4" feed negate any
increase?

you certainly won't gain any PRESSURE by increasing the line. But you
can LOSE pressure if the line is too small. What you will do with a
larger line is eliminate any possibility of pressure drop due to
frictional losses. How far are you going? and do you really need a butt
load of pressure? Are you just filling tanks, or are you hosing out
stalls and need a good jet stream? I personally would not even bother
going up to the one inch, unless you're going over 500 feet, or up a
hill. One inch and one-and-a-quarter are quite a bit more expensive
than 3/4" also.

--
Steve Barker
remove the "not" from my address to email

"mm" wrote in message
...
On Tue, 10 Aug 2010 17:28:07 -0500, "The Post Quartermaster"
wrote:


"dpb" wrote in message
...
The Post Quartermaster wrote:
I'm going to run a water line out to a little outbuilding I have
out near the barn. The line I am going to tap off of is probably
a
3/4" line. If I run a larger diameter, say a 1 or 11/4 inch from
there to the outbuilding would that result in any increase in
pressure at the outbuilding or would the fact that there was a
3/4"
feed negate any increase?

Larger will reduce the pressure drop would otherwise have.
Neither
will increase pressure above supply--it only drops, never goes up.

How long a run?

--

40 feet maybe. I just dug a two foot deep trench by hand so it feels
like it was a couple of hundred feet. And the thermometer is showing
102 in the shade.

But you weren't in the shade all the time, so you should be okay.

Yeah but October a year from now I'll be 70 and right now I feel like
I past that a couple of years ago. It's so hot down here in south
Texas that the damn water moved over under a shade tree. Now I've to
dig a trench over there and lay some more pipe.
--
Careful how you respond. I have people!

JC

On 2010-08-10, The Post Quartermaster
wrote:

I'm going to run a water line out to a little outbuilding I have out
near the barn. The line I am going to tap off of is probably a 3/4"
line. If I run a larger diameter, say a 1 or 11/4 inch from there to
the outbuilding would that result in any increase in pressure at the
outbuilding or would the fact that there was a 3/4" feed negate any
increase?

The way to approach this question is what are the water uses you will
have in the outbuilding and what flow rates do they demand? If you
just have a lavatory, it only needs 1.5 gpm, and since you said it is
only 40', the 3/4" pipe will be fine, and you'll never see the
difference if you upsize to 1" pipe. But if you want to fill a
bathtub as quickly as possible, then yes, the 1" pipe will give you
more flow.

Cheers, Wayne

"Wayne Whitney" wrote in message
...
On 2010-08-10, The Post Quartermaster
wrote:

I'm going to run a water line out to a little outbuilding I have
out
near the barn. The line I am going to tap off of is probably a 3/4"
line. If I run a larger diameter, say a 1 or 11/4 inch from there
to
the outbuilding would that result in any increase in pressure at
the
outbuilding or would the fact that there was a 3/4" feed negate any
increase?

The way to approach this question is what are the water uses you
will
have in the outbuilding and what flow rates do they demand? If you
just have a lavatory, it only needs 1.5 gpm, and since you said it
is
only 40', the 3/4" pipe will be fine, and you'll never see the
difference if you upsize to 1" pipe. But if you want to fill a
bathtub as quickly as possible, then yes, the 1" pipe will give you
more flow.

Cheers, Wayne

Thanks to ya all. I went with the 3/4 all the way because I had enough
of it on hand. I appreciate the responses. I learned something and at
my age that's always good.
--
Careful how you respond. I have people!

JC

The Post Quartermaster wrote:
"mm" wrote in message
...
On Tue, 10 Aug 2010 16:50:40 -0500, "The Post Quartermaster"
wrote:

I'm going to run a water line out to a little outbuilding I have out
near the barn. The line I am going to tap off of is probably a 3/4"
line. If I run a larger diameter, say a 1 or 11/4 inch from there to
the outbuilding would that result in any increase in pressure at the
outbuilding or would the fact that there was a 3/4" feed negate any
increase?

If the valve on the spigot or outlet you'l be using has a greater
diameter than the one on the 3/4" pipe, you'll have LESS pressure.
There is no way to get more in pounds per square inch than the 3/4
has.

Also the extra length of pipe lowers the pressure some, but not very
much, maybe not even noticeable. Using larger diameter pipe will
make
the effect of that less, but maybe not noticeably.

How long will the pipe be and why do you need more pressure?

It's only about 40 feet, if that. The place we bought has 3/4 all the
way from the well to the old house, about 125 feet. The pressure is
okay, I just thought I might lose some by extending it. I'm probably
going to upgrade all the pipe in a year or so after I get some of the
really necessary things done. Like a place to actually put a bed to
sleep on, and things like that. G They told us it was a 150 year old
farmhouse. Well, really it's a 150 year old woodpile.

Is the pressure tank in the house? If so, that's where the pressure drop starts,
unless you are drawing more water than the pump can supply at pressure. 40 feet
of additional 3/4" pipe shouldn't have much drop unless you are using a lot of
water. Certainly, 1" pipe shouild be more than big enough.

"Wayne Whitney" wrote
But if you want to fill a
bathtub as quickly as possible, then yes, the 1" pipe will give you
more flow.

How so? The 3/4" pipe feeding it will still give the same flow, as will the
faucet opening at the tub.

On 2010-08-11, Ed Pawlowski wrote:

"Wayne Whitney" wrote

But if you want to fill a bathtub as quickly as possible, then yes,
the 1" pipe will give you more flow.

How so? The 3/4" pipe feeding it will still give the same flow, as
will the faucet opening at the tub.

Here's how fluid flow works:

You can assume the water main or pressure tank is a roughly constant
pressure source. When water is flowing each element (pipe, valve,
water heater, etc.) between and the source and the outlet contributes
pressure drop depending on the flow rate. As you open an outlet, the
flow rate starts at zero and climbs until the total pressure drop
equals the source pressure. That is, once the water droplets are
flying through the air, the pressure is zero.

In the case of a bath tub filler, it is usually designed to have a big
opening with very little pressure drop compared to other components in
the system. As opposed to a lavatory faucet, where it is designed to
have a pretty rapidly increasing pressure drop as you exceed the
federally mandated 1.5 gpm maximum flow.

Back to the case of the OP, he mentioned 40' from the main building to
the outbuilding. For a simple example suppose the interior piping in
the main building was also 40' of 3/4" copper and there are no other
sources of pressure drop. Now the pressure loss per foot of 1" piping
is roughly 1/3 of that of 3/4" piping (it depends on the ratio of the
interior diameters, which for copper pipe depends on the wall
thickness, type K, L, M).

So the difference between 3/4" and 1" outbuilding piping is 2 units of
pressure loss versus 4/3 units of pressure loss, or a ratio of 3:2.
Since pressure drop varies as roughly the square of flow rate, the
ratio of the flow rates is about sqrt(3:2), or 1.2. That is, in this
simple example you'd expect 20% more flow with the 1" pipe.

Cheers, Wayne

On 8/10/2010 9:16 PM, Wayne Whitney wrote:
On 2010-08-11, Ed wrote:

"Wayne wrote

But if you want to fill a bathtub as quickly as possible, then yes,
the 1" pipe will give you more flow.

How so? The 3/4" pipe feeding it will still give the same flow, as
will the faucet opening at the tub.

Here's how fluid flow works:

You can assume the water main or pressure tank is a roughly constant
pressure source. When water is flowing each element (pipe, valve,
water heater, etc.) between and the source and the outlet contributes
pressure drop depending on the flow rate. As you open an outlet, the
flow rate starts at zero and climbs until the total pressure drop
equals the source pressure. That is, once the water droplets are
flying through the air, the pressure is zero.

In the case of a bath tub filler, it is usually designed to have a big
opening with very little pressure drop compared to other components in
the system. As opposed to a lavatory faucet, where it is designed to
have a pretty rapidly increasing pressure drop as you exceed the
federally mandated 1.5 gpm maximum flow.

Back to the case of the OP, he mentioned 40' from the main building to
the outbuilding. For a simple example suppose the interior piping in
the main building was also 40' of 3/4" copper and there are no other
sources of pressure drop. Now the pressure loss per foot of 1" piping
is roughly 1/3 of that of 3/4" piping (it depends on the ratio of the
interior diameters, which for copper pipe depends on the wall
thickness, type K, L, M).

So the difference between 3/4" and 1" outbuilding piping is 2 units of
pressure loss versus 4/3 units of pressure loss, or a ratio of 3:2.
Since pressure drop varies as roughly the square of flow rate, the
ratio of the flow rates is about sqrt(3:2), or 1.2. That is, in this
simple example you'd expect 20% more flow with the 1" pipe.

Cheers, Wayne

WOW! Wayne has WAY WAY over thought this out. LOL!

--
Steve Barker
remove the "not" from my address to email

On 2010-08-11, Steve Barker wrote:

WOW! Wayne has WAY WAY over thought this out. LOL!

Actually I just worked it out as an example for the public good. :-)

Wayne

On Aug 10, 7:38*pm, Steve Barker wrote:
On 8/10/2010 9:16 PM, Wayne Whitney wrote:



On 2010-08-11, Ed *wrote:

"Wayne *wrote

But if you want to fill a bathtub as quickly as possible, then yes,
the 1" pipe will give you more flow.

How so? *The 3/4" pipe feeding it will still give the same flow, as
will the faucet opening at the tub.

Here's how fluid flow works:

You can assume the water main or pressure tank is a roughly constant
pressure source. *When water is flowing each element (pipe, valve,
water heater, etc.) between and the source and the outlet contributes
pressure drop depending on the flow rate. *As you open an outlet, the
flow rate starts at zero and climbs until the total pressure drop
equals the source pressure. *That is, once the water droplets are
flying through the air, the pressure is zero.

In the case of a bath tub filler, it is usually designed to have a big
opening with very little pressure drop compared to other components in
the system. *As opposed to a lavatory faucet, where it is designed to
have a pretty rapidly increasing pressure drop as you exceed the
federally mandated 1.5 gpm maximum flow.

Back to the case of the OP, he mentioned 40' from the main building to
the outbuilding. *For a simple example suppose the interior piping in
the main building was also 40' of 3/4" copper and there are no other
sources of pressure drop. *Now the pressure loss per foot of 1" piping
is roughly 1/3 of that of 3/4" piping (it depends on the ratio of the
interior diameters, which for copper pipe depends on the wall
thickness, type K, L, M).

So the difference between 3/4" and 1" outbuilding piping is 2 units of
pressure loss versus 4/3 units of pressure loss, or a ratio of 3:2.
Since pressure drop varies as roughly the square of flow rate, the
ratio of the flow rates is about sqrt(3:2), or 1.2. *That is, in this
simple example you'd expect 20% more flow with the 1" pipe.

Cheers, Wayne

WOW! *Wayne has WAY WAY over thought this out. *LOL!

--
Steve Barker
remove the "not" from my address to email

Actually Wayne saved me from having to develop a pressure drop matrix
as a function of flow vs pipe size .

Here is a link to a calculator that allows you to determine pressure
drop as a function of pipe size and flow.

http://www.freecalc.com/fricfram.htm

bottom line.....if the flow is low (like a few gpm), the pressure drop
will be low, pretty much independent of pipe size.
if the flow is high (10 gpm +) ....pipe size is more important.


cheers
Bob

On Tue, 10 Aug 2010 16:50:40 -0500, The Post Quartermaster wrote:

I'm going to run a water line out to a little outbuilding I have out
near the barn. The line I am going to tap off of is probably a 3/4"
line. If I run a larger diameter, say a 1 or 11/4 inch from there to the
outbuilding would that result in any increase in pressure at the
outbuilding or would the fact that there was a 3/4" feed negate any
increase?

Keep the same size.

Wayne Whitney wrote:
On 2010-08-11, Ed Pawlowski wrote:

"Wayne Whitney" wrote

But if you want to fill a bathtub as quickly as possible, then yes,
the 1" pipe will give you more flow.
How so? The 3/4" pipe feeding it will still give the same flow, as
will the faucet opening at the tub.

Here's how fluid flow works:

You can assume the water main or pressure tank is a roughly constant
pressure source. When water is flowing each element (pipe, valve,
water heater, etc.) between and the source and the outlet contributes
pressure drop depending on the flow rate. As you open an outlet, the
flow rate starts at zero and climbs until the total pressure drop
equals the source pressure. That is, once the water droplets are
flying through the air, the pressure is zero.

In the case of a bath tub filler, it is usually designed to have a big
opening with very little pressure drop compared to other components in
the system. As opposed to a lavatory faucet, where it is designed to
have a pretty rapidly increasing pressure drop as you exceed the
federally mandated 1.5 gpm maximum flow.

Back to the case of the OP, he mentioned 40' from the main building to
the outbuilding. For a simple example suppose the interior piping in
the main building was also 40' of 3/4" copper and there are no other
sources of pressure drop. Now the pressure loss per foot of 1" piping
is roughly 1/3 of that of 3/4" piping (it depends on the ratio of the
interior diameters, which for copper pipe depends on the wall
thickness, type K, L, M).

So the difference between 3/4" and 1" outbuilding piping is 2 units of
pressure loss versus 4/3 units of pressure loss, or a ratio of 3:2.
Since pressure drop varies as roughly the square of flow rate, the
ratio of the flow rates is about sqrt(3:2), or 1.2. That is, in this
simple example you'd expect 20% more flow with the 1" pipe.

Cheers, Wayne


Hate to be picky, Wayne. But.... I agree with everything you say up
until the last sentence. If the 3/4' and 1" pipes were connected to the
same source, and are flowing at the same time, then yes, you'd get more
flow from the 1" pipe.

But, as in the OP's case, he mentioned feeding 1" pipe from 3/4" pipe
and you will not get any more flow than the 3/4" pipe is providing.
although the friction loss in the 1" pipe is less that that in the 3/4"
pipe the gpm flow through the 1" pipe is not going to be any greater
than that received from the 3/4" pipe.

That's why fire departments use large size lines to feed pumpers from
hydrants and static sources, so they may feed a number of smaller size
lines whose combined discharge flows can not exceed the flow from the
supply line(s).

I may be wrong, but that's my take on it.

Gil

On 2010-08-12, Gil wrote:

But, as in the OP's case, he mentioned feeding 1" pipe from 3/4" pipe
and you will not get any more flow than the 3/4" pipe is providing.
although the friction loss in the 1" pipe is less that that in the 3/4"
pipe the gpm flow through the 1" pipe is not going to be any greater
than that received from the 3/4" pipe.

Sorry, that's not how it works. For a constant pressure source, less
friction loss gives more flow.

It's like resistors in series (V = pressure, I = flow) connected to a
constant voltage source, except for each "resistor" the V-I relation
is roughly V = I^2 R.

Wayne

Wayne Whitney wrote:
On 2010-08-12, Gil wrote:

But, as in the OP's case, he mentioned feeding 1" pipe from 3/4" pipe
and you will not get any more flow than the 3/4" pipe is providing.
although the friction loss in the 1" pipe is less that that in the 3/4"
pipe the gpm flow through the 1" pipe is not going to be any greater
than that received from the 3/4" pipe.

Sorry, that's not how it works. For a constant pressure source, less
friction loss gives more flow.

....

Thru that section, yes. But, to be clear, the more flow is relative to
the reduction in what comes out the end of the new section owing to the
added pressure differential. There's not going to be more coming out of
the opening into that section than the upstream pressure there supplies.

--

Hi Gil,

I read your post too quickly the first time, let me try again at
responding to it:

On 2010-08-12, Gil wrote:

Hate to be picky, Wayne. But.... I agree with everything you say up
until the last sentence. If the 3/4" and 1" pipes were connected to
the same source, and are flowing at the same time, then yes, you'd
get more flow from the 1" pipe.

In the OP's example, he is considering extending his system with
either 3/4" or 1" pipe. So in the two cases we are comparing, the
pipes would be connected to the same source.

But, as in the OP's case, he mentioned feeding 1" pipe from 3/4" pipe
and you will not get any more flow than the 3/4" pipe is providing.

You won't get any more flow than the 3/4" pipe would provide at the
point of attachment of the new pipe. But you will get more flow at
the end of the new pipe when the new pipe has lees fricional loss.

Cheers,
Wayne

On 2010-08-12, dpb wrote:

But, to be clear, the more flow is relative to the reduction in what
comes out the end of the new section owing to the added pressure
differential. There's not going to be more coming out of the
opening into that section than the upstream pressure there supplies.

I agree, thanks for pointing out my first response to Gil was a bit
sloppy.

Cheers, Wayne

Perhaps what you're trying to say? The larger pipe will preserve
whatever flow and capacity is available at the end of the 3/4. But, it
won't increase pressure, or GPM rate.

However, using smaller pipe may reduce the flow, pressure, or GPM.

I'd be concerned that some future plumber might see the larger pipe,
and assume that it was larger, all the way back.

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


"Wayne Whitney" wrote in message
...

You won't get any more flow than the 3/4" pipe would provide at the
point of attachment of the new pipe. But you will get more flow at
the end of the new pipe when the new pipe has lees fricional loss.

Cheers,
Wayne

On 8/13/2010 6:26 AM, Stormin Mormon wrote:
Perhaps what you're trying to say? The larger pipe will preserve
whatever flow and capacity is available at the end of the 3/4. But, it
won't increase pressure, or GPM rate.

However, using smaller pipe may reduce the flow, pressure, or GPM.

I'd be concerned that some future plumber might see the larger pipe,
and assume that it was larger, all the way back.


why would that concern you?

--
Steve Barker
remove the "not" from my address to email