Piping a hydronic system is a key part of the installation process. It requires time and skill as contractors work to provide top-performing hydronic systems.

One integral consideration with hydronic piping is its composition. Each type of piping available has a list of benefits and trade-offs, depending on the application. To help contractors choose, here is a look at the different types of piping available — along with some trends, tips, and tricks to simplify hydronic piping installation and maintenance.



Hydronic piping traditionally consists of carbon steel or black iron pipes, along with copper and other metals. For example, installations that have large amounts of piping or higher flow rates are often served with carbon steel. Other benefits of metal and copper piping focus on cost, availability, and the common specification of the material. In fact, most of the hydronic installations today still involve these material choices, but other materials are making inroads in hydronic installations as well.

“While copper and steel are the traditional piping materials used in most commercial hydronic applications, more engineers and contractors are realizing the benefits of PEX pipe for these types of applications,” said Aaron Stotko, senior manager, commercial segment, Uponor. “PEX does not pit, scale, or corrode, and it also helps promote safer job sites due to its lighter weight.”

Officially known as cross-linked polyethylene, the presence of PEX tubing in hydronic applications is increasing, both in residential and commercial applications. It is available in continuous coil lengths up to 1,000 feet for smaller diameters. Polypropylene (PP) and polyethylene raised temperature (PE-RT) are two other types of plastic-based tubing used to pipe hydronic applications.

“The PP pipes will typically have a fiberglass reinforcement layer, providing higher rigidity and reduced thermal expansion,” said James Paschal, P.E., LEED AP, chief technology officer of Aquatherm. “PP and PE-RT are available in larger diameter pipes as well.”



More than piping materials is progressing in the hydronic piping process. The jobsite is changing, too, and one of the changes is the need for increased speed. Time is money, and the less time spent on a job site, the more money contractors can put on their bottom line.

Along with increased profits, some of the newer installation techniques are also improving safety and decreasing maintenance. To help increase speed, some manufacturers and contractors are working with prefabrication. This allows contractors to make, or to have made by the manufacturer or distributor, some of the piping connections offsite and bring them to the job in larger sections to be connected in a plug-and-play manner. This practice can not only lessen job site labor time, but it also addresses safety and labor shortages, said Barry Campbell, vice president, marketing, Aquatherm.

“Polypropylene is ideal for prefabrication because it weighs up to 75 percent less than carbon steel,” he explained. “Prefabrication can decrease the need for qualified welding technicians, helping to decrease the effects of the skilled labor shortage.

Stotko pointed out that in the ever-increasing focus on driving down site-related injuries, product weight is an important consideration.

“A stick of copper is three times heavier than a stick of PEX, and steel is heavier than both of them,” he said.

Connection speed is affected by piping choices, too. It is directly influenced by how technicians choose to connect hydronic piping: welding, heat fusion, or press systems. Welding is still a primary choice among contractors, be it copper or black steel applications. To go along with welding water, compressed air, and gas applications, there are press systems available that change the pace and makeup of the job site. For example, these flameless connections provide benefits when working in tight spaces as well as in places where flame connections are not advisable.

For plastic-based piping, heat fusion joining methods are helping to reduce installation time and costs. According to Campbell, the heat fusion process allows users to use the machine on one side of the PP pipe while at the same time prepping the other end of the pipe for the next fusion. This heat fusion technique, among others, can provide labor savings.

Stotko said for PEX piping systems, the ASTM F1960 ProPEX expansion method is easy to learn and fast to install, aiding contractors who are looking to meet tight production schedules. There are also many ASTM F1960 transitions available for copper press, copper thread, copper sweat, and CPVC piping systems.

“In the mechanical room, the decision to use plastic piping can have a significant impact on the amount of treatment chemicals required for protection of the boilers, chillers, and other components,” said Paschal. “Heat fusion joining and prefabrication can provide significant reductions in installation costs.”



Several piping trends will continue to develop over time — one of which is the market sector’s further reach into sustainability, partially fueled by customer demand.

“While there’s a perception that plastics are bad, and of course, most would agree single-use plastics are not an environmentally friendly solution, polymer piping solutions are actually a good option from a sustainable perspective,” said Stotko. “They last for a very long time. Many industries have already made the transition away from metals and toward polymers, and I believe our industry will undergo the same transformation as well.”

The basis of this comes from the understanding that, prior to the discovery that ethane could be refined into long-chain polymers, the ethane was regarded as a waste product with no value, he explained.

“With the development of long-chain polymers, this waste byproduct has been developed into a catalyst that is currently evolving the way we think about commercial piping systems,” said Stotko. “We should be specifying solutions, not because they are the incumbent materials, but because they are the best choice for the built environment. Many industries have already made the transition away from metals and toward polymers, and I believe our industry will undergo the same transformation as well.”

Piping efficiency and design continues to be an important focus and the digitization of piping measurements is helping contractors become increasingly accurate.

Aquatherm now offers a service where a trained technician can go to the job site with a 3-D digital camera and scan the mechanical room to get extremely accurate measurements.

“It reduces the man hours to measure and line up the mechanical room or any kind of a tight space,” said Campbell. “It facilitates quicker installation on complex projects.”

According to him, the drawings created from this scanner are accurate down to plus or minus one millimeter with a fabrication tolerance of one eighth of an inch.

“It really can be a game changer for certain applications, especially retrofits,” said Campbell. “Retrofits are a large portion of the market for us right now. The company is seeing all these situations where old office buildings and warehouses are becoming apartments and mixed use facilities, and that’s trending overall in the industry.”


Plastic Pipe Design Tool

The Building and Construction Division (BCD) of the Plastic Pipe Institute (PPI) has several resources for the understanding, design, and installation of plastic pipe for hydronic systems. One of those tools is The BCD Plastic Pressure Pipe Design Calculator. This software tool aids in designing plastic pressure pipe and tubing systems using PEX, PE-RT, and CPVC. It is intended to assist designers using these materials for applications such as plumbing, water service, fire protection, hydronic piping (general), radiant heating, radiant cooling, snow and ice melting, geothermal ground loops, district heating, and turf conditioning.

The tool includes functions to calculate pressure/head loss, pipe weight/volume, thermal expansion/contraction, hydraulic shock, and expansion arm/loop design. It utilizes dimensional data from ASTM and CSA Group industry standards for these materials, as well as data generated from various PPI research projects.

The calculator provides for a selection of working units, either IP/US or Metric/SI. Various fluids can be selected such as water, propylene glycol or ethylene glycol, with temperatures and mix ratios chosen by the user. The BCD calculator allows the results to be viewed, printed, or emailed.

— Source: PlasticPipeCalculator.com


Pipe Joining for Plumbing and Heating Systems

There are hundreds of types of pipe, fittings, and joining methods now available that are suitable for plumbing and hydronic heating and cooling systems. They range from traditional materials and methods, such as solder copper tubing, to modern materials and methods such as socket fusion of polyethylene pipe. A favorite to the webinar series, John Siegenthaler, P.E. will summarize where several types of materials and joining systems are best applied in plumbing and hydronic systems. He will also discuss basic pipe and fitting standards and nomenclature.

Topics covered in this 90-minute webinar include:

  • What’s the difference between the copper tubing used in hydronic systems versus that used in refrigeration applications?
  • What do the terms SD9, SCHD40, 150#, and FTG refer to in regards to piping and fittings?
  • What is the correct way to specify pipe sizes on a reducing tee?
  • What’s the difference between a standard and inverted flare joint?
  • Can a shape memory PEX compression fitting be used with PE-RT tubing?
  • Is it possible to join PEX tubing using socket fusion?

Coffee with Caleffi technical training webinars are free and intended for contractors, designers, and wholesalers. All attendees receive a certificate of attendance following the event. The webinar archive is available on YouTube 24/7 for convenience.

— Source: Caleffi Hydronic Solutions

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