How to Size Your Water Lines (PEX & Copper)

Summary

In 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

00:00

🔍 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.

05:01

📏 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.

10:02

🛠 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.

15:03

🏠 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.

Keywords

💡PEX

PEX, which stands for cross-linked polyethylene, is a flexible tubing used in plumbing for water supply lines. In the video, PEX is discussed as a material for water lines, and the speaker mentions sizing PEX water lines according to the 2018 Uniform Plumbing Code. The video also touches on the difference between PEX A and PEX B, which relates to the type of fittings used and potential flow reduction due to the fittings' design.

💡Plumbing Code

The Plumbing Code refers to the set of regulations that dictate the installation and design of plumbing systems to ensure safety, health, and compliance with local standards. The video specifically references the 2018 Uniform Plumbing Code as the basis for sizing water lines, indicating that the speaker is adhering to a recognized set of guidelines to ensure the plumbing work is up to standard.

💡Sizing

Sizing in the context of plumbing refers to determining the appropriate diameter of pipes and tubing to handle the water flow and pressure required for a specific application. The video script describes a method for sizing PEX, copper, and other types of water lines, emphasizing the importance of proper sizing to ensure adequate water supply to fixtures.

💡Fixture Units

Fixture Units are a measure used in plumbing to quantify the demand a fixture places on a water supply system. Each type of fixture, such as a sink or shower, is assigned a fixture unit value based on its water usage. In the video, the speaker calculates total fixture units by adding up the values for various fixtures in the house to determine the demand on the water system.

💡Developed Length

Developed length is the total linear distance along the centerline of a pipe from the water supply to the most remote fixture. The video explains how to calculate the developed length by tracing the path from the water meter to the farthest fixture, which is crucial for sizing the water lines correctly.

💡Elevation

Elevation in plumbing refers to the vertical height difference between the water supply and the highest fixture. The video script mentions calculating the elevation to account for pressure drop due to gravity, which affects the water pressure at the fixture. For every foot of elevation gain, there is a 0.5 psi pressure drop.

💡Pressure Drop

Pressure drop is the decrease in water pressure as it travels through pipes due to friction and elevation changes. The video discusses how elevation affects pressure drop, which is an important consideration when sizing water lines to ensure that fixtures receive adequate water pressure.

💡75 Method

The 75 method is a rule used in plumbing to size water lines, where the fixture unit demand is multiplied by 0.75 when both hot and cold water supplies are provided to a fixture. This method is used in the video to reduce the calculated load on the water line, allowing for smaller pipe sizes where applicable.

💡Static Pressure

Static pressure, also known as the pressure at the source of supply, is the water pressure at the point where water enters the plumbing system. The video script describes measuring static pressure and using the lowest pressure during high demand periods to ensure the plumbing system is designed to handle varying pressures.

💡Branch Lines

Branch lines in plumbing are the sections of pipe that extend from the main water supply line to individual fixtures. The video script describes how to size branch lines based on the total fixture units they serve, using the 75 method and the developed length to ensure adequate water flow to each fixture.

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