How to Size Your Water Lines (PEX & Copper)
Summary
TLDRIn this video, plumber Quinn educates viewers on sizing PEX water lines for residential plumbing projects, following the 2018 Uniform Plumbing Code. The 75% method simplifies calculations for DIYers and professionals alike. Quinn explains how to determine fixture units, calculate developed length, and account for elevation and pressure. The video also addresses the nuances between PEX A and PEX B materials, offering practical advice for ensuring optimal water line sizing.
Takeaways
- 🛠️ The video is a plumbing tutorial focused on sizing PEX water lines, with applicability to PEX, copper, and other materials.
- 🏡 It's based on the 2018 Uniform Plumbing Code and uses the '75 method', which is suitable for private residences and DIY projects.
- 📏 The process starts with sizing the water meter to ensure it can handle the water demand of the project.
- 📋 Total fixture units are calculated by assigning values to each fixture from a code book and summing them up.
- 📏 The 'developed length' of the most remote outlet is determined by tracing the center lines of the pipes back to the meter.
- 📏 The elevation of the highest fixture is calculated to account for pressure drop due to height.
- 💧 The static pressure of the system at the source of supply is crucial, especially during periods of high demand.
- 🔍 The video uses Table 610.4 to determine the appropriate pipe size based on developed length, pressure range, and total fixture units.
- 🔄 The '75 percent method' is applied to fixtures with both hot and cold water supply to reduce the load on the system.
- 🔍 Sizing each branch involves calculating the total fixture unit load and referring to the table to determine the necessary pipe size.
- ⚙️ There's a discussion on the differences between PEX A and PEX B, with a suggestion to consider upscaling pipe sizes if using PEX B due to potential flow reduction from insert fittings.
Q & A
What is the purpose of the video by Quinn the plumber?
-The purpose of the video is to educate viewers on how to size PEX water lines, including copper, and to discuss the differences between PEX A and PEX B, particularly in relation to sizing.
What method does Quinn recommend for sizing water lines in private residences?
-Quinn recommends using the '75 method' for sizing water lines in private residences, which is based on the 2018 Uniform Plumbing Code.
What is the first step in sizing a water line according to the video?
-The first step in sizing a water line is to size or verify the capacity of the water meter to handle the project's requirements.
What are the key factors considered when sizing a water meter?
-The key factors considered when sizing a water meter are total fixture units, developed length of the most remote outlet, elevation of the highest fixture, and the pressure in the system.
How are fixture units calculated in the video?
-Fixture units are calculated by assigning a value to each fixture from a table in the code book, which represents the demand each fixture puts on the water system, and then summing these values.
What is the significance of the developed length in water line sizing?
-The developed length is the distance from the water meter to the farthest fixture in the house, traced along the center lines of the pipes, and it affects the sizing of the water lines.
How does the elevation of the highest fixture impact the water line sizing?
-The elevation of the highest fixture impacts the water line sizing by affecting the pressure in the system; for every foot of elevation gain, there is a 0.5 psi pressure drop.
What is the '75 percent method' mentioned in the video?
-The '75 percent method' is a technique used to size water lines where if a fixture has both hot and cold water supplied, the fixture unit is multiplied by 0.75 to reduce the load on the system.
How does Quinn address the difference between PEX A and PEX B in the context of water line sizing?
-Quinn suggests that while there's no exact way to account for the difference in flow due to PEX B's insert style fittings, one might consider upsizing the pipe if they are on the border between pipe sizes to account for potential flow reduction.
What is the final check Quinn recommends after sizing all the branches in the water system?
-After sizing all the branches, Quinn recommends checking that the total load on the main supply line matches or is less than the capacity determined during the water meter sizing process.
Outlines
🔍 Introduction to Sizing PEX Water Lines
Quinn, a plumber, introduces the video by addressing diamond hands and GameStop lovers, hinting at a financial context. The main focus is on how to size PEX water lines, with an application to PEX, copper, and a discussion on the difference between PEX A and PEX B towards the end. The video adheres to the 2018 Uniform Plumbing Code, using the 75 method suitable for private residents and DIY enthusiasts. Quinn aims to help viewers size water meters and supply lines for various fixtures like water heaters, kitchen sinks, and bathrooms, both upstairs and downstairs. The process involves calculating total fixture units, developed length of the most remote outlet, elevation of the highest fixture, and system pressure.
📏 Calculating Water Supply Requirements
The video explains the process of calculating the total fixture units by assigning values to each fixture from a code book, which represents the demand on the water system. Quinn details how to calculate the developed length from the farthest remote outlet, tracing the center lines of pipes to determine distance. The elevation of the highest fixture is also calculated to account for pressure drop, with a loss of 0.5 psi for every foot of elevation gain. The video then proceeds to determine the static pressure of the system, crucial for sizing pipes accurately. Using these variables, Quinn demonstrates how to consult tables to find the appropriate pipe sizes for the water supply.
🛠 Sizing Branches Using the 75 Percent Method
Quinn explains the 75 percent method for sizing branches in a water supply system, which applies when both hot and cold water lines are supplied to a fixture. This method reduces the fixture unit count by 75 percent, allowing for smaller pipe sizes. The video walks through the process of sizing hot water lines, starting from the most remote outlet and working back towards the water meter. Each branch's size is determined by adding the fixture units of the connected fixtures and checking these against a table to ensure the pipe can handle the load. Quinn also highlights the importance of considering the inlet size of fill valves in bath shower combos.
🏠 Finalizing Pipe Sizing and Discussing PEX A vs PEX B
The video concludes with the sizing of cold water lines, following a similar process to the hot water lines but without the 75 percent reduction since only cold water is involved. Quinn emphasizes the need to check the minimum branch size, especially with different fill valve sizes. The video also addresses the difference between PEX A and PEX B, noting that PEX B, with its insert-style fittings, may have a slight reduction in flow. Quinn suggests upsizing pipes if the fixture units are near the maximum capacity for a given pipe size to account for this. The video ends with a call to action for viewers to ask questions and suggest topics for future videos.
Mindmap
Keywords
💡PEX
💡Plumbing Code
💡Sizing
💡Fixture Units
💡Developed Length
💡Elevation
💡Pressure Drop
💡75 Method
💡Static Pressure
💡Branch Lines
Highlights
Introduction to PEX water line sizing based on the 2018 Uniform Plumbing Code.
Explanation of the 75% method, which is the easiest method for sizing water lines in private residences.
First step: size the water meter and verify its capacity for any project expansions.
Calculate total fixture units by assigning a value to each fixture in the house based on demand.
Determine the developed length from the farthest remote outlet and calculate the total pipe length.
Account for elevation differences between fixtures, affecting water pressure due to elevation gain or loss.
Calculate the real water pressure after factoring in elevation and system fluctuations.
Plugging the fixture units, pressure, and developed length into Table 610.4 to determine pipe size.
Use the 75% method to calculate pipe sizing by multiplying fixture units for hot and cold water fixtures by 0.75.
Verification of the pipe sizes for each branch in the system, checking if the load allows for half-inch, three-quarter-inch, or one-inch pipes.
Reassess the fixture values for toilets, which require full values due to cold water supply only.
Explanation of the critical load calculations for multiple fixtures, ensuring proper pipe sizing throughout.
Final verification of total fixture units for the system, comparing against the overall load capacity.
Discussion of the differences between PEX A and PEX B, particularly regarding flow reduction due to insert fittings.
Recommendation to upsize pipes when near fixture unit thresholds, especially when using PEX B to prevent flow restrictions.
Transcripts
hey this is quinn your favorite plumber
here to congratulate you diamond hands
stonk trading game stop lovers
hey everyone it's quinn your favorite
plumber here to talk about
how to size your pex water lines this
applies to pex
copper and at the end of the video we're
going to talk about the difference
between pex a and pex p
and how that can affect your sizing this
video is based on the 2018 uniform
plumbing code
we're going to use what's called the 75
method which is
the easiest method especially for
private residents
and all you diyers if you're making an
addition or
starting from scratch we've got a lot of
comments asking for this video so i hope
this helps
let's get started
okay the first thing we need to do is
size our water meter
or verify that our existing water meter
has capacity to expand on whatever
project we're working on so size the
meter and the water supply for the
building
in this example we have our water meter
here we have a water heater
we have a kitchen sink a bathroom group
downstairs which
is comprised of a lav a toilet a shower
and a bathroom group upstairs with the
same fixtures in this example
in my awesome art i have the blue drawn
out as cold water lines
and then the pink is going to be our hot
water lines
to size the meter we're going to need a
few things we're going to need total
fixture units
we're going to need the developed length
of the most remote outlet
the elevation of the highest fixture and
then also the pressure
in the system so the first thing we need
to do is calculate our total fixture
units
which is essentially how much demand we
have
on the water system in the house so each
fixture is assigned a value
from a table in our code book on how
much demand it puts on that system so
we're going to add those all up when
you're calculating the
total fixture units we're in private
because it's a private residence
and we're just finding bathtub
combination bathtub is for
and then kitchen sink so sink down to
kitchen domestic with or without a
dishwasher
is 1.5 one other thing we need to keep
in mind
is the minimum fixture branch size is
listed here
so that fixture cannot be supplied with
anything
less than what's in this column so if
we're going through this
the kitchen sink is 1.5 fixture units
the lav is one the toilet is 2.5
the bath shower combo is four and once
again the upstairs one is the same
the lab is one this 1.6 gallon gravity
flush toilet
is what we have in this house is 2.5 and
then the bath shower combo is 4.
so we're going to add those up so the
kitchen sink is 1.5
plus the lab is one plus the toilet is
2.5
plus the bath shower combo is four plus
the upstairs lab
is one plus the toilet is 2.5
plus the bath shower is four
totaling 16.5 water supply fixture units
the next thing we need to do is
calculate the developed length
from the farthest remote outlet so the
fixture that's the farthest away from
our meter
trace that back along the center lines
of the pipes and how far
is that away that's called the developed
length so the
most remote outlet means the very
farthest away fixture in the house
which in this case is the upstairs bath
shower
and so once we find that the develop
length is basically tracing center line
so 10 feet then it goes up 10 feet over
5 feet into the water heater then we're
over 10
up 10 over 60 up eight
and back over two so that's the
developed length of the most remote
outlet we're gonna have to check my math
on this one again 10
plus 10 plus five
plus 10 plus 10
plus 60 plus
8 and plus 2. so this is going to be the
the develop length of the most remote
outlet is
115 feet the next thing we need to do is
calculate the elevation of the highest
fixture so what is the difference
between the elevation
of the meter to our most highest remote
outlet
so in this example we have a fixture on
the second floor
and in this example we'll say it's 12
feet higher
so from here
to our meter this will be 12 feet and
why that's important is because it
affects our
pressure so if your highest fixture is
above
basically for every foot of elevation
gain
you're losing 0.5 psi so in this example
this 12 times 0.5
we're going to have 6 psi pressure drop
here once again if your meter is above
the basement that'll actually
add to your psi whereas above is
subtracting so keep that in mind
next we need our pressure or static
pressure of our system
at the source of supply if there's
pressure fluctuations throughout the day
you're going to want to use your lowest
pressure so in your city if you have
pressure fluctuations make sure you kind
of
check it during the high demands where
everyone's taking showers and the lowest
pressure you see is the one you should
use
in this example we read 60 psi
so to get the real pressure we take our
reading minus the elevation of our
highest outlet
and that is 54
psi that we will use in our tables so
that's the last variable
we need to now start plugging these in
now we're looking in
table 610.4 okay the top part
is the maximum allowable length so this
is our developed link to the most remote
outlet
our developed linked the most remote
outlet is 115
so it's between 100 and 150 here you
always have to round up so we're going
to be in this column of 150
and then the next thing we use is this
pressure range so our pressure range
was 54 psi so it's going to be in this
table
down here between the 46 and 60
psi the next thing we need is the total
number of fixture units
we have 16.5 so you'll see here
that 16.5 is between 14 and
28 once again we always round up and so
our meter will be three quarter inch and
our building supply will start at one
inch
so the next thing i like to do is to
make note of this
and jot this down because we're always
going to stay in this column
our one inch pipe can have up to 30
fixture units
next up is the three quarter can have up
to 14
and our half inch line can have up to
four
now that we've got the size of the meter
verified that
now we need to size each branch of our
system we're going to be using what's
called
the 75 percent method the 75
method means that if there's both a hot
water
and cold water supplied to the fixture
we get to use that fixture unit
times it by 0.75 or 75 percent
and get to use that number to size each
branch
let's start with the hot water we need
to size this section here we'll start
here
which is supplying branch a here
so this shower has both hot and cold
and we have a fixture unit here of four
and because we're using the 75 method
because it has both hot and cold
we get to times 4 by 0.75 which is
three and if we take a look back at our
notes from our table
half inch can carry up to four so this
is okay to run this as a half inch line
right there
one thing to be aware of when you're
sizing the bath shower combos
is the inlet size of those
of your fill valve the three quarter
inch fill valve have larger fixture
units
and minimum fixture branches that you're
going to have to keep an eye out for
now working backwards the next little
branch we're sizing is from this t
to this lav here we'll call this branch
b and it is only supplying the hot water
here on this lab at 0.75 so obviously
0.75 is less than four so that can be
half inch as well
essentially as we're working upstream
we're basically looking at
what section of pipe and as we pick up
additional fixtures
what is that additional fixture load and
what is the new size that we have to
make that pipe so that's all we're doing
is we're working back
adding on fixtures and increasing the
load and checking it against
our table to see if we have to increase
the pipe size now
we move back to this section this
section of the hot water
is now not only carrying the lav but
it's also carrying the shower
so the total fixture unit at this
section
is the .75 plus the
three so we have 3.75 at this section
and so 3.75 total fixture unit load on
this
and we look back at our notes it's still
less than four so this is still okay to
be half
inch so basically from this line here is
all
half inch now we're gonna move
downstairs and do the same exercise
similar to this one we have a bathtub
with total fixture units of four
because it has both a hot and a cold
going to it we get to use the .75 method
so that is three this section is only
picking up
this bath shower so the total load of
this branch
is three fixture units and going back to
our table
three is less than four so we can get
away with half inch there
then we have this branch that's picking
up the hot water of the lav
since the lab has both hot and cooled we
times it by 0.75
so that branch line is 0.75 and can be
serviced with a half inch
so this section from here to here
which has to pick up and carry the lav
and the shower
we have the shower at 3 plus the lab at
0.75 so we have a total of 3.75
fixture units which is less than four so
that can be
carried by a half inch now we work our
way back
we're picking up a kitchen sink this
kitchen sink
has a fixture unit of 1.5
because it has both hot and cold we
times it by 75
or 0.75 that comes out to be 1.125
which can be a half inch now
we have this section here so this
section
right here is picking up the kitchen
sink the lav
and the bath shower on the hot water
line toilets only have cold water going
to them
so working back we have this section is
3.75 so if we add in
the 1.12 so that's 4.875
if we look back to our little cheat
sheet from our table half inch can only
have
four on it since we're above four we
need to round up
and supply this branch from here to here
is going to be three quarter inch
so now when we teed in this section
so this section is 4.875
fixture units and then our upstairs
total load from this section picking up
everything upstairs is 3.75
so we add 3.75 to 4.875
and we get 8.625 8.625 is still less
than 14 so we're still
okay with three quarter inch here we are
now done sizing our hot water side
so in summary from here to here is three
quarter inch
the olive upstairs is half inch and then
down here
it's three quarter inch to here our
kitchen branch is half
inch and then it transitions to half
inch here to supply half inch to the
lav and bath shower next let's take a
look at cold water
so it's the exact same thing we're still
using our cheat sheet
we'll start up here on the shower shower
is four
because we have both hot and cold going
to this fixture we can reduce the load
on the system
using our 75 rule to get three so this
branch
is three and back to our cheat sheet
half inch can carry up to four
so this is half inch here now we're
looking at the toilet branch
this toilet because it only has cold
water we can't reduce it with our 75
rule and have to use the full fixture
value of 2.5 here
and we're gonna do this section from
here to here because this section
is carrying downstream fixtures of 2.5
and three
the total load for this is 5.5 here
so 5.5 is greater than four
so this section has to be three quarter
inch
now we size our lav lab has both hot and
gold
its fixture value is one so we can times
it by point seven
five so this branch is half inch
there's no fixtures between here and
here so now we're going to size from
this section and its upstream value is
the lav at .75 plus 5.5
which is this section's value so now
that branch
is 6.25 which back to our cheat sheet
has to be three quarter inch so we got
all the upstairs branches done we'll do
the same here
bath shower is four times 0.75 because
we both have hot and cold
am i getting repetitive yet on that
that's three which is
adequate for half inch remember to take
a look at the size of this
fill valve because if it's a half inch
fill valve versus a three quarter inch
connections on these
tub shower fillers that changes your
minimum branch size so really take a
look at that
when you're sizing this so then we hit
our toilet this toilet branch is 2.5 so
it has a half
inch remember we can't times it by 0.75
because it just has cold going to it
this section is carrying everything
above
2.5 and this three so we have
5.5 on this section which
now has to be three quarter inch okay
now we pick up a lav so this little
branch
lav has both hot and cold so that's 0.75
that's under 4 so we can decide that
it's half inch
and now this section is picking up
everything upstream which is now
the 5.5 plus our additional lav so we
got
6.25 here and that is three quarter inch
now working back now we hit a kitchen
sink which has both hot and cold
1.5 times our 75
rule 1.125
which can be a half inch so now this
section
is carrying our kitchen sink at 1.125
plus everything upstream
which is 6.25 so that totals
7.375 which is still
in our three-quarter now we're hitting
this t that picks up
everything from upstairs so our upstairs
load we calculated from early is 6.25
plus everything from downstairs is 7.375
13.625
13.625 is still less than 14
but getting very close so this can still
be three quarter inch
and then when we hit this t we have to
remember that it's now picking up our
hot water
fixture units at 8.625 so we're adding
those total branches from here to the
meter
which is 22.25
which is one inch and it's
good because when we sized the water
supply we came out with one inch
and that kind of double checks it you'll
notice that our 22.25
is greater than our total fixture units
of 16.5
because we use the 75 method so you
never have to size over than
your maximum fixture unit but it was one
inch anyway
so didn't change it there so now we're
done
as i've mentioned this is how to size
universal water lines so this can be pex
copper galvanized whatever your system
is this applies to it
this sizing method one comment we're
getting a lot of questions about
is the difference between pex a and pex
b how the pex b has the insert style
fittings
and has a little more reduction in flow
when you have a fitting in pex b
how do we how do we account for that the
answer is there's not a great way to
account for it
but what i would do is if you're looking
at your line and you're
running into a lot of fixtures where
that insert style fitting
is reducing flow if you're looking back
at sizing these lines
if you're on the border for example
you're at 13
and three-quarter can hold up to 14.
maybe you should upsize that to one
or if you're running half inch and half
inch can have four fixture units and
you're at three already
maybe you should upsize that to three
quarters so there's no
uh exact science to it but essentially
if you're on those borders between the
pipe sizes
maybe it's worth upsizing a little bit
more and as always thanks for watching
guys
let us know if you have any questions
we'll try to get them answered in the
comments
and if you are interested in learning
something post that below
like us subscribe that always helps and
thanks for watching
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