What is PEX?PEX is cross-linked Polyethylene. Through one of several processes, links between polyethylene macromolecules are formed to create bridges between PE molecules (thus the term "cross-linked). This resulting molecule is more durable under temperature extremes, chemical attack, and resists creep deformation, making PEX an excellent material for hot water applications (up to 200° F).
How long has PEX been used?
PEX was developed in the 1960s. PEX tubing has been in use in many European countries for plumbing, radiant heating and snow melt applications since that time. PEX was introduced in the United States in the 1980s, and has seen significant growth in market demand and production.
What are recommended uses for PEX?
PEX 's flexibility and strength at temperatures ranging from below freezing up to 200 degrees Fahrenheit makes it an ideal piping material for hot and cold water plumbing systems, hydronic radiant heating systems, snow melting applications, and, even ice rinks and refrigeration warehouses.
Why is PEX an excellent piping material for plumbing?
PEX is ideally suited for potable water plumbing applications. It is flexible, making it easy to install and service. PEX is able to withstand the high and low temperatures found in plumbing and heating applications, and is highly resistant to chemicals found in the plumbing environment. Although not freeze proof, PEX also provides the homeowner with many useful benefits. Flexible systems are quieter than rigid piping. The smooth interior resists scale buildup and corrosion that can affect long term pipe flow characteristics. PEX is also very freeze- break resistant. Finally, PEX systems have attractive installation costs when compared with rigid materials. PEX is the best piping material for many plumbing applications, but not for outdoor or UV exposed applications.
How can I be sure that PEX is a safe product for plumbing?
PEX is manufactured and tested according to stringent national consensus standards: ASTM F 876 and F 877. Both the product manufacturer and independent third party testing agencies conduct routine quality control and quality assurance evaluations to insure the product meets ASTM and NSF Standards. Compliance with the standards ensures the end user of safety and quality. Additionally, PEX is included in all of the major model plumbing codes used in the United States and Canada, CSA, IAPMO, SBCCI, BOCA, ICBO, IPC and NSPC, and approved by HUD for hot and cold potable water plumbing use.
Where is PEX approved for use?
PEX is an approved material in all the current edition national model-plumbing codes; however, some jurisdictions using older versions of these codes may not have amended the code to include PEX tubing . Contact the local authority with jurisdiction over plumbing to verify the acceptance of PEX tubing for plumbing applications in your area.
Can PEX be used under the slab?
Yes. The flexibility of PEX allows it to be supplied in coils meaning installations under the slab can be made with a single, continuous length without the need for fittings under the slab. PEX is not affected by concrete, or chemicals in concrete (it is commonly encased in concrete for radiant floor heating). PEX, however, must be sleeved when penetrating a concrete slab.
Can PEX be used for underground cold-water service applications?
Yes. Although the high temperature resistance of PEX makes it particularly suitable for hot and cold interior plumbing applications, it also makes an excellent underground water service piping. It can be installed using the same fittings recommended for copper tube sized SDR-9 polyethylene tubing.
Can PEX be used for aboveground outdoor applications?
No. PEX is designed for indoor and buried applications only and is not recommended for outdoor, aboveground use. Short exposures to sunlight are permissible, not to exceed 30 - 60 days. When storing PEX, it must be stored under cover, shielded from direct sunlight.
Can PEX save me money?
Yes. PEX saves money in many ways. For the installer, PEX tubing is competitively priced. Installation of flexible systems is fast because of the easy handling nature of the tubing and because a PEX installation requires fewer directional fittings. Since most plumbing problems occur at joints, fewer fittings also reduce the chances for callbacks, saving the installer even more time. The homeowner saves in the cost of the installed system, fewer callbacks, and reduced utility costs when home-run manifold systems are utilized in conjunction with PEX.
Will PEX systems help save on utility bills?
Yes. Home run or manifold plumbing systems utilizing PEX tubing can substantially reduce water and energy consumption in a home. The home-run concept provides dedicated direct lines from the manifold to the fixtures, reducing the amount of water that must be purged from the lines to get hot water at the fixture. Direct lines can be sized to the fixture requirements, further reducing the amount of time to wait for hot water. Faster hot water delivery reduces water waste and the amount of times the water heater must cycle to supply hot water.
What is the expected performance of PEX water distribution systems?
PEX is designed and tested to perform as well or better than any other material approved for hot and cold-water distribution systems. For indoor plumbing applications, PEX is expected to perform as long as copper, CPVC or any other approved plumbing distribution materials.
What joining systems are available?
There are several methods of connecting PEX, all of which involve mechanical fittings. There are two approved standard specifications for PEX connections: ASTM F 1807 and ASTM F 1960. Both reference mechanical insert fittings. The crimp fittings specified in ASTM F1807 are the most widely used. Other fitting systems, including insert and outside diameter compression fittings, are also available. PEX cannot be joined by solvent cement or heat fusion methods.
Which manufacturing method for PEX is recommended for hot and cold potable water?
There are currently three methods for producing PEX tubing, the Engle or Peroxide method, the E-beam or radiation method and the Silane method. All three processes produce tubing cross-linked to varying degrees that result in a product acceptable for potable water distribution applications. All PEX that has been tested and certified for potable applications carries the mark(s) of nationally recognized third-party certification agencies such as NSF, IAPMO, ICBO-ES, Warnock Hersey or UL.
How long can PEX be exposed to sunlight?
PEX tubing is not intended for outdoor applications and must be stored in a covered environment not exposed to direct sunlight. Maximum UV exposure is no more than 60 days.
What are temperature limitations for PEX?
PEX tubing can be used up to 200° Fahrenheit for heating applications. For plumbing, PEX is limited to 180° F. Temperature limitations are always noted on the print line of the PEX tubing. Recommended 140 max for safety and conservation
How are PEX systems tested for leaks?
PEX plumbing and radiant heating systems can be pressure tested using either water or air to check for leaks. Follow manufacturer's instructions.
How soon after installation can you pressure test a PEX tubing installation?
PEX plumbing systems can generally be tested immediately after the installation is complete. There is no wait time for glue to dry or joint to cool off. Weather should be considered and manufacturer's instructions followed in cold weather.
Where is PEX available?
PEX is available through almost all plumbing wholesale distributors throughout the United States and Canada. Many retail building supply outlets also supply PEX piping and fittings. Piping and fittings are commonly available in 1/4" through 1" CTS (Copper Tube Size) with some manufacturers also supplying larger sizes up to 2." Because the wall-thickness is proportionate for each size, the pressure ratings are the same for all sizes.
What sizes, lengths and packaging options of PEX are available?
PEX is available in 1/4" through 1" CTS (Copper Tube Size) and is packaged in coils or 20' straight lengths. Some manufacturers tubing is color-coded for easy identification of hot and cold lines. Coil lengths generally run to a maximum of 1000' and are available in a variety of shorter lengths.
Is flexible PEX plumbed differently than rigid material plumbing systems?
Yes. The flexibility of PEX allows many directional changes to be made without fittings, but, PEX systems are sized in the same fashion as copper or CPVC plumbing systems. PEX piping is also used in high performance manifold plumbing systems that takes advantage of the flexibility and economical cost of PEX tubing.
What are manifold plumbing systems?
Manifold or home run plumbing systems are much like a breaker box for the electrical system in the home. The manifold provides a common location from which all the plumbing fixtures are supplied. Some high-end manifolds also feature fixture shut-off valves allowing the user to shut off the water to individual fixtures from one location. Others are semi-home run manifolds or termination manifolds, which may feed the plumbing requirements for a room or set of rooms and reduce the number of fittings required in the plumbing system.
How are PEX systems sized?
PEX systems are be sized just like other plumbing materials such as copper or CPVC when used in a branch-and-main installation. To take advantage of utility savings and system performance issues of branch-and-main systems, PEX can be sized in manifold systems to meet the specific demands of each fixture, reducing water and energy waste in the home.
Is the thermal expansion/contraction of PEX a problem?
No. While PEX expands more than other plumbing materials, directional changes made with the tubing and some slack in the tubing during installation accommodate the expansion and contraction of the system if properly installed.
Is PEX freeze-break resistant?
PEX piping is freeze damage resistant and can expand and contract as water freezes and thaws within the tubing. No tubing material is freeze-break proof, however, and PEX should be installed using the same locally-prescribed insulation requirements to prevent freezing of any plumbing system.
How do I thaw PEX lines?
When water freezes inside PEX tubing, it can be thawed using a hair dryer, warm wet rags or heat tape, taking care not to overheat the tubing beyond it's maximum recommended temperature.
Can PEX be joined with solvent cement?
No. PEX cannot be joined with solvent cement, or heat fusion. PEX is installed using only mechanical fittings either inserted in or around the tubing or by compression fittings.
Can I add radiant floor heat to my existing home?The answer to this question must be given after careful consideration to your particular situation. Ultimately, when there is a will there is a way, but sometimes the price and effort can surpass your reason and motivation. We have been involved in many remodeling situations where the addition of radiant panel heat has been both an appropriate and preferred way to heat the new or remodeled space. The first questions that must be answered are: 1) Does the home have existing radiant heat? 2) Is the new radiant heat addition designed for space heating or just floor warming? 3) What areas of the home are to be heated? 4) Can the area being heated accept the tubing and light-weight concrete topping slab? 5) If there is no existing heat source, is there a location where water, gas, electricity and a flue can be installed for the new boiler? Radiant additions to homes with an already existing hydronic system are more straight forward. Any new addition needs to be prepared to accept the tubing and concrete covering and depending on the increased heat load may require upgrading the boiler to a larger size. For homes where radiant heat does not exist, there are different choices on how to condition the space. These include but are not limited to heat in the walls, joist spaces, and under sub-floors by installing an emitter plate attached to the flexible tubing which dissipates and directs the heating into the room area. Also, electrical l radiant floor mats are available to warm floors when space does not permit other options. These choices are only for small areas where floor warming and no space heating is required. True radiant panel heat if installed on a wood sub-floor is always encased in a thin concrete slab usually a mimimum of 1” thick and preferably 1-1/2” thickness or more. When installed on grade, the slab thickness can vary from 4”-18” depending on structural requirements. The concrete provides thermal mass and the radiation panel for which the heat is stored and delivered to the structure. We only design and install radiant heat where concrete encases the tubing because it is the best method and design to properly space heat the entire home. A system which does not use a concrete slab to encase the tubing has a myriad of possible problems with tubing performance. The largest problem with adding radiant panel heat to an exisitng home is the requirement to raise doors, cabinets, toilets, tubs, showers and appliances to accept the system because of added height created by the new concrete slab. Some areas may be easier than others to perform the installation and may or may not affect the status of the existing items. Floor coverings also will require removal and replacement for the newly heated areas. Sometimes homes have windows which span to the floor as well. All these factors must be considered. A full scale remodel of a home accomodates the installation of the new system much better than a limited remodel. If radiant heating is desired for just a small addition such as a bathroom or kitchen which is to be retiled, the tubing system can be laid in the tile mortar. The system can use a heat source like an existing water heater with a heat exchanger and some support equipment or a new boiler system, all of which depends on the size of the addition. Floor warming sensors can be provided to regulate floor temperature or thermostats to control room temperatures. Our design engineers can assist with further questions regarding your project and help determine whether or not the application of radiant heat is appropriate.
I just want to add radiant heat in my bathrooms, or basement, or garage. What is involved?
First you must determine whether you want the added radiant heat area to be used for floor warming or space heating. The difference between the two can affect the overall design requirements. Does the home already have another heating system for those areas? A basement or garage addition normally would be used for space heating and would require a reasonable amount of input to heat because of the increased concrete mass commonly found in both areas. Bathrooms are fairly simple additions and can use a water heater or boiler system. A garage or basement usually would use a boiler. Remember, the per square foot cost is higher for small additions since the heat source equipment must be provided no matter what the size of the system. Is the house new construction? Or is it a partial remodel? If not, why not install radiant throughout? Certain options exist to accommodate all different design plans but providing the right recommendations requires additional input about the scope of the project. Many partial home and small radiant panel additions have been completed with great success. Consult our design department with your additional questions.With radiant panel heat nearly any floor covering you desire can be used. If you have concrete floors, a handsome economy floor finish, which can last for years, can be achieved by simply staining or waxing the concrete floor finish. A radiant heated concrete floor is actually no less resilient than a well-built frame floor and because of its solid construction is amazingly quiet as well as pleasantly warm. Rugs and other floor coverings are really optional with radiant heat. Colorful tile, vinyl , asphalt, cork, etc. and even hardwood flooring has been laid directly over the warmed concrete with great success. Because of the way radiant heat works to heat a space, relatively low floor temperatures are required to provide heat. Most wooden flooring manufacturers warranty their products to surface temperatures not exceeding 85 degrees F which a radiant panel shouldn’t need to surpass. In fact, sunlight, shining through a window onto your floor will increase temperatures beyond that. Wooden flooring has been installed directly bonded to the concrete floors or even floating on top. Either way works well. Just remember to allow all the wood flooring products to acclamate to the house environment for several days prior to installing. Luxurious wall-to-wall carpeting and rugs of all kinds can be used for your pleasure. Tests conducted by carpet manufacturers prove that the gentle warmth of a radiant heated floor is an usually good climate for even the finest rugs. It is recommended to use a carpet padding with as little insulating properties as possible to allow the transfer of heat. Usually thin and dense rubber pads work better than the thicker waffle type paddings. Ask the hydronic design engineer for a pad recommendation rather than the carpet installer.
What about floor finishes? Can I have any type? Can you use hardwood for a floor covering? What about carpet over radiant floors?
Should radiant tubing be installed under cabinets and bathtubs?
As a general principle when designing a radiant heating system, you should keep the tubing circuits out from underneath cabinets and appliances; however, we often heat under showers and bathtubs as requested. The overall heating of the structure is not affected from the absence of tubing in such areas. The main reasoning for keeping tubing away from cabinet areas is to prevent damage due to cabinet fastening and drilling into the slab. If drilling is required and tubing is placed under cabinets, circuits should be accurately measured and marked on the plans prior to pouring the concrete slab for later identification.Surveys conducted by an outside agency of the industry revealed overwhelmingly the enthusiastic acceptance of radiant heat installations. It was also revealed even in an attractive and successful tract house, 98% of the owners polled considered the radiant heat the most desirable feature of their home.
What do people who have lived with radiant heat think of it?