Radiant installation at Loyola University Lake Shore Campus in Chicago. Photo courtesy of Hill Mechanical Group.


For quite a while now I’ve been interested in radiant systems and hydronics, having been introduced to them through the writings and webinars of our Hydronics Editor John Siegenthaler, P.E. Equally important is my reading of the annual Radiant Flooring Guide (polybagged with this issue).

Recently I spoke to Siggy about the state of commercial hydronics in 2009. He noted some solid trends, including:
  • Green design and a desire by designers to obtain LEED points through any devices or applications that reduce energy consumption.

  • Strong interest in solar thermal systems for water and space heating and geothermal water-to-water heat pumps tied to radiant floor heating.

  • Greater availability and interest in larger diameter (over 1-inch) PEX, and polymer composite tubing to displace copper for distribution piping.

    One manufacturer of such tubing (polypropylene pressure piping) is Aquatherm, Inc. At the recent ASPE Expo, I asked its president, Steve Clark, P.E., what plumbing engineers can do to increase radiant’s presence in commercial construction.

    “In the short term, they can propose radiant heat for new markets (such as condos, hotels, commercial buildings), reduce system installation costs, and integrate radiant cooling into designs. Also, they need to let owners know how much they can save by going from electric resistance heat to hydronic radiant.”

    Long term, Clark says it’s important for designers to work on code committees to achieve balanced codes, including the elimination of return air plenum loopholes, which Clark calls “a subsidy for central air systems.”

    Reiterating the importance of engineers’ role in expanding commercial radiant is Geoff McDonell, P.E., LEED AP, senior mechanical engineer for OMICRON in Canada.McDonell says that less than two percent of all new construction building projects over 10,000 sq. ft. feature radiant installations, although the percentage has increased in the last five years.

    “The increase is due to more designers becoming familiar with radiant systems, more PEX tube supplier technical support, and the desire by many building clients to achieve lower energy costs while maintaining comfort.”

    McDonell acknowledges that cost and technical design expertise/knowledge are still major barriers for radiant to penetrate the bulk of the building design industry. He also says that the cost issue is more perception than reality - claiming that a complete radiant floor or ceiling installation is actually cheaper than conventional all-air HVAC systems when done by an experienced radiant system trade/contractor.

    “Designers need to educate themselves on how radiant systems work and how to design them.”

    To paraphrase a more famous commercial - Let’s Do It.