This two-part article provides in-depth details about PEX water pipe systems.  Al’s Plumbing, Heating & A/C in Plano, Texas is near your home in Plano, TX; Allen, TX; and Frisco, TX.  We service all homes in southern Collin and Denton Counties with no travel charges.  Al’s provides Full-Service Plumbing Maintenance, Repairs & Replacements for every plumbing component in your home.  Al’s sells and installs Rheem Professional Series gas & electric water heaters, and tankless water heaters.  Call Al’s today to discuss any concerns or problems you have with your HVAC System or Plumbing.  We will arrange an appointment at your convenience.

Al’s also provides maintenance & repairs for all brands of Central A/C, Gas & Electric Furnace, and Heat Pumps.  Additionally, we sell & install new HVAC Systems from American Standard (same company as Trane), Ameristar (same company as American Standard) and Coleman HVAC (same company as York HVAC).

This Is Part-1 Of Our Two-Part Article.  For Part-2 Click Here: AlsPlumbing.com PEX Water Pipe – Part 2

What Is PEX Water Pipe?

Image Source: ShutterStock

Shown: PEX Water Pipes (red=hot & blue=cold) With Brass Fitting (Connections)

PEX is flexible water pipe made of Crosslinked, High-Density Polyethylene (HDPE) — (crosslinking details below).   PEX was invented in 1968, when a scientist discovered a way to crosslink polyethylene to make it stronger and more flexible.  PEX plumbing has been in use in Europe since the early 197o’s, and in the U.S. the early 1980’s.  Today, PEX is used in 60% of newly-built homes in the U.S.

There Are 3 Types Of PEX Pipe — The Primary Difference Their Method Of Crosslinking

Image Source: ShutterStock

Shown: Blue PEX is for cold water.  Red PEX is for hot water.  White PEX can be used with both cold & hot water.

What Is PEX “CrossLinking”?

Crosslinked Polyethylene undergoes a change in molecular-structure — where carbon atoms (inside the molecules) are permanently linked to each other.  Crosslinking results in improved chlorine (and other chemicals) resistance, and high-temperature tolerance.

NOTE: A, B, C Is Not A Quality Rating  — it indicates only the method of crosslinking.

There Are 3 Different PEX Crosslinking Methods:

• PEX-A:  PEX-A is used mostly for hot-water heating systems.
• PEX-A crosslinking is done using peroxides while the polyethylene is above its melting point — creating crosslinking at about 85%. **

• PEX-B:  This is the most widely used for water lines.   Crosslinking is done by placing the pipe in a hot-water bath or steam sauna.  The degree of crosslinking is typically 65–70%.
• Independent testing shows PEX-B has equal or better resistance to oxidation.   The oxidation appears to be the primary reason for the formation of cracks in earlier PEX pipes.

• PEX-C:  It’s crosslinked using an electron beam.  This degree of crosslinking is 70–75%.   Other than a marginally higher crosslinking — PEX-C appears to offer little advantage over PEX-B.

PEX Fittings — Types

• Note: PEX pipe can be bent a radius of up to 6 times the diameter of the PEX pipe.   Example: a 1/2-inch diameter PEX pipe can have up to a 3″ bend radius.

• The ability to bend PEX reduces the need for many fittings.

• There may be a lot of fittings in a complex PEX pipe installation.

• PEX fittings connect two (or more) pieces of PEX together.

Examples Of Commonly Used Fittings:

• Fittings used to; connect two pieces of PEX together — “COUPLING”

• Where water pipe direction changes — “ELBOW”.

• To supply water from one pipe to two additional pipes –“TEE”.

• PEX CRIMP-Rings secure the PEX pipe onto fittings.  Crimp-rings are made of copper or stainless-steel. 

• PEX CLAMP-Rings are used when PEX is connected to a different type of water pipe (such as copper).  Clamp-rings are made of brass or stainless-steel. 

• The PEX manifold (described later) — reduces the number of fittings tremendously.
• With a manifold — in many instances, a single piece of PEX pipe can connect to the manifold on one end — and the faucet on the other end.

Copy The Link Below To See Stainless-Steel Push-Fit (sometimes called “Push To Connect”) Fittings: 

https://www.grainger.com/category/plumbing/pipe-tubing-and-fittings/tube-fittings/push-to-connect-tube-fittings-and-accessories/push-to-connect-tube-fittings?attrs=Tube+Fitting+Material%7C316+Stainless+Steel&filters=attrs

Note: Metal fittings may be more subject to corrosion.  This depends on the amount of zinc in a brass fitting, and how corrosive the water is.  Stainless-steel fittings are very corrosion resistant.

PEX Fittings — Materials They’re Made Of

• PEX Metal fittings — are typically made of brass or stainless steel.
• PEX Plastic fittings — are made of corrosion-resistant polymer plastic.

Note:

1. DeZincification occurred in some early brass fittings  — and weakened the fittings over time.  Most PEX companies now use dezincification-resistant brass.
2. It’s advised not to buy foreign-made brass fittings because some are prone to dezincification.

Look For These Designations On Brass PEX Fittings:  

• ASTM (American Society for Testing and Materials)
• NSF (National Science Foundation)
• ULC (Underwriter Laboratories of Canada

EXAMPLE: Matco-Norca’s (Brewster, NY) lead-free brass PEX fittings are rated as:

• ASTM Standard F1807
• NSF-Approved
• UPC-approved

Click Here To Read More About Matco-Norca Fittings In Plumber Magazine: Matco-Norca Fittings

• PEX Poly (polymer / plastic) fittings are made of high-performance, non-degradable, thermoplastic. 
• They have high tolerance to oxidation (becoming brittle) when exposed to chlorine.
• PEX fittings are ideal for hard (high lime content) or acidic water.
• These fitting are said to have better resistance to chlorine than some of the inexpensive brass fittings.

Copy This URL Into Your Browser To See Poly Allow PEX Fittings:  https://www.pexuniverse.com/poly-pex-fittings 

PEX Pipe & Fittings Performance Standards

PEX pipe and fittings are rated by The American Society For Testing & Materials (ASTM) headquartered in West Conshohocken, PA.  ASTM creates standards and designations for products.  ASTM International is one of the largest standards development organizations in the world.  ASTM is a not-for-profit organization that provides the development of international standards for materials, products, systems, and services.

PEX PIPE:

• ASTM F876 Standard Specification for Crosslinked Polyethylene (PEX) Tubing.

• ASTM F877 Standard Specification for Crosslinked Polyethylene (PEX) Plastic Hot- and Cold-Water Distribution Systems.

• ASTM F2023 Standard Test Method for Evaluating PEX Tubing’s Oxidative Resistance to Hot Chlorinated Water.

• ASTM F1281 Standard Specification for PEX with an Aluminum Core (PEX-AL-PEX) Pipe.

Copy This Link Into Your Brower To See A PEX Pipe With ASTM Designations:

https://www.google.com/search?q=pex+pipe+astm+rating&tbm=isch&ved=2ahUKEwjd8_D49sXsAhUT0qwKHe9gChAQ2-cCegQIABAA&oq=pex+pipe+astm+rating&gs_lcp=CgNpbWcQA1CMP1itQmCIRWgBcAB4AIABOIgBOJIBATGYAQCgAQGqAQtnd3Mtd2l6LWltZ8ABAQ&sclient=img&ei=IEqQX93jNZOkswXvwamAAQ&bih=646&biw=1280#imgrc=hkTEp1J6P8ouUM

(The Blue Pipe At The Top Shows:”ASTM 876/877/2023″).

ASTM 2023 Requires That PEX Meets Or Exceeds These Standards

• A minimum lifespan of 50 years. *4
• Temperature Tolerance: Up to 248°F.                         Note: Residential hot water recommendation is 120°F 
• Chlorine-Concentration Tolerance: Up to 4.3 ppm.  Note: Chlorine levels in the U.S. are limited to up to 4.0 ppm by the U.S. EPA.
• Water-Pressure Tolerance: 100 psi at 180°F              Note: Typical city water pressure = 45 Pounds Per Square Inch (psi).

• PEX is resistant to acidic water.  Untreated acidic water will corrode copper.
• PEX is resistant to hard water (lime) build-up.  Untreated hard water causes lime-scale deposits on copper.
• PEX is not affected by galvanic-corrosion.
• Galvanic-corrosion is caused by the electrical current that’s created when two different metals are in contact with each other and water.  It’s often seen at water heaters, where the steel pipe (from the water heater) meets the home’s (copper) water pipe.*5  NOTE: Galvanic-corrosion can be prevented using plastic spacers between different pipe metals.

Click Here To See Galvanic-Corrosion Caused By Copper Pipe Touching Steel Pipe: Galvanic-Corrosion

Click Here To See A Plastic Spacer Designed To Prevent Galvanic-Corrosion: Plastic Space To Prevent Galvanic-Corrosion

PEX FITTINGS ASTM Specification:

• ASTM F1807 Standard Specification for Brass Insert Fittings With a Copper Crimp-Ring for SDR9 For Use with PEX Tubing (PEX pipe).

• ASTM F1960 Standard Specification for Cold Expansion Fittings with PEX Reinforcing Rings for Use with PEX Tubing.

• ASTM F2080 Standard Specification for Cold-Expansion Fittings with METAL Compression-Sleeves for Use With PEX Tubing.

• ASTM F2098 Standard Specification for Stainless Steel Clamps for Securing SDR9 PEX Tubing to Metal Insert Fittings.

• ASTM F2854 Standard Specification for Push-To-Connect Fittings.

• ASTM F2159 Standard Specification for Polymer (plastic) Fittings.

Source: http://www.pexinfo.com/astm-standards.htm

Image Source: ShutterStock

Shown: A PEX “Manifold” Creates A Separate Hot & Cold Water Line To Each Faucet

Benefits Of A PEX Water Pipe System

PEX BENEFITS FOR THE HOMEOWNER:

• PEX is quieter than metal or rigid plastic — because water flows more easily through PEX.
• The noise from copper pipe is eight times louder than PEX-a pipe. ***
• Also, more fittings cause more water turbulence — which creates additional noise.  Copper pipes have far more fittings.  One is required with each direction change.

*** Source: https://www.plumbermag.com/how-to-articles/plumbing_commercial_residential/pex_101_everything_you_need_to_know_about_flexible_plastic_piping

Image Source: ShutterStock

Shown: PEX Water Pipes Are Flexible — And Require Fewer Fittings

Image Source: ShutterStock

Shown: Copper Water Pipes Are Rigid — And Require A Fitting At Every Direction Change

Copper has a large pipe (trunk line) connected to many smaller pipes (branch lines).  The large pipe must first be filled with hot water first — up to pipe for the fixture.

Image Source: ShutterStock

Shown: A Smaller Copper Pipe (branch line) Connected To A Larger Pipe (trunk line) — At The Faucet.

• PEX has a water shut-off for every hot & cold water line.  With copper pipe, every faucet connected to the main line stops flowing when the main line is turned off.

• PEX delivers hot water faster than copper — because each faucet has its own separate water lines.

• PEX uses 32% less water than copper because PEX deliver hot water faster.

• PEX has insulating properties that reduce heat loss (from hot water) by up to 15% as compared to copper.

• PEX reduces water heating costs by 1/3 as compared to copper.

• PEX has minimal water-pressure changes due to each fixture having its own water lines.  With copper, turning on one faucet (particularly a bathtub) can affect every faucet on the main line.

• PEX is more resistant to freeze damage because it can expand a little.  Frozen water will burst a copper pipe.

• Because scrap copper is so valuable — vacant homes are broken into to strip & steal copper (this is much more of a problem in areas with basements, as they provide easy access to copper).

• Repiping the home and repairing the damage done (during stripping) can cost thousands of dollars.  Copper theft in 2013 was estimated at $1 billion.

Copy The Link Below Into Your Browser For An Article About Vacant Homes Being Stripped Of Copper Water Pipes AND Copper Gas Pipes (resulting in explosions):

On Minneapolis’ North Side, copper-theft epidemic adds to mounting housing problems

TIP: How To Reduce Water Pipes Noise In Existing Walls

Seal all gaps between electrical boxes (outlets & light switches) — and the drywall.  Noise takes the path of least resistance — and more noise comes through openings.  Caulk is the easiest way to seal gaps.  Then add foam gaskets over the openings before reinstalling the cover.

NOTE: The Gaps Are Sealed In Homes 2015 and newer. **

NOTE: This also reduces heating and cooling bills.

Copy The Link Below Into Your Browser To See A Common Gap Around An Electrical Box  

https://www.google.com/search?q=gap+around+electrical+box&sxsrf=ALeKk02u5f64E5eycK69ycXqwO6YGH8kxQ:1603727121243&source=lnms&tbm=isch&sa=X&ved=2ahUKEwi99oKLzdLsAhUDEqwKHdMrB1EQ_AUoAnoECAMQBA&biw=1280&bih=608#imgrc=fBwKh5EZmjd8tM

Image Source: Amazon Embedded Link

Shown: Foam Gaskets For Electrical Outlet & Light Switch Openings.

Click On Link To; View Product, See Details, or Purchase From Amazon.com

Air-Leakage Standards For Newly Built Homes Over The Years

A DFW home built during the 1970’s ranges from 17 or more Air Changes Per Hour (ACH) during a Blower-Door Test.  The 2009 International Residential Code (IRC) required all houses to have no higher than 7 ACH.  In 2015 the 2015 International Energy Conservation Code (IECC) required all new newly built homes have no more than 3 AC — and ACH must be verified with a “blower-door pressure test” (see photo just below).

** Source: https://codes.iccsafe.org/content/IECC2015/chapter-4-ce-commercial-energy-efficiency

Image Source: ShutterStock

Shown: Blower Door (temporarily) installed to perform an air-leakage test.

TIP: To Reduce Water Pipes Noise While Installing Water Lines Inside Walls

Reduce water pipes noise with water pipe insulation.  It’s pre-cut and slips onto the water pipe.  The dB noise reduction of foam pipe insulation (shown below) is -2dB.  This will the noise volume from the pipes by 10%. **

** -10dB is considered to reduce volume by 50% to most listeners.  So, each -1 dB = 5% less loud.

** Source: http://insulationinstitute.org/wp-content/uploads/2016/01/BI476.pdf

Image Source: Amazon.com Embedded Video

Shown: Foam Water Pipe Insulation

Click On Image To; View Product, Read Details, or Purchase From Amazon.com

Image Source: Amazon.com Embedded Video

(Image Is Not To Scale)

Shown: 3″ Thick Fiberglass Water Pipe Insulation

Click On Image To; View Product, Read Details, or Purchase From Amazon.com

This product provides about -3 db in noise volume reduction.  This product (shown just above) will reduce noise from the pipes by -15%.

** -10dB is considered to reduce volume by 50% to most listeners.  So, each -1 dB = 5% less loud.

** Source: http://insulationinstitute.org/wp-content/uploads/2016/01/BI476.pdf

This is Part-1 of a two-part article and provided in-depth details about PEX water pipe systems.  Al’s Plumbing, Heating & A/C in Plano, Texas is near your home in Richardson, TX; Garland, TX; and northeast Dallas, TX.  We service all homes in southern Collin and Denton Counties with no travel charges.  Al’s provides Full-Service Plumbing Maintenance, Repairs & Replacements for every plumbing component in your home.  Al’s sells and installs Rheem Professional Series gas & electric water heaters, and tankless water heaters.  Call Al’s today to discuss any concerns or problems you have with your HVAC System or Plumbing.  We will arrange an appointment at your convenience.

Al’s also provides maintenance & repairs for all brands of Central A/C, Gas & Electric Furnace, and Heat Pumps.  Additionally, we sell & install new HVAC Systems from American Standard (same company as Trane), Ameristar (same company as American Standard) and Coleman HVAC (same company as York HVAC).