Copyright Goodheart-Willcox Co., Inc. Chapter 12 Radiant Heating Systems 253 spots over the tubing, particularly when the floor covering has a low resistance factor—the pipe hangers will prevent the tubing from making direct contact. Another method of installing suspended tubing is to use aluminum heat transfer plates fastened to the tubing or directly to the subflooring and spaced evenly throughout the floor joist, Figure 12-31. This may be a better method because the aluminum heat transfer plates spread the heat energy from the tubing more evenly throughout the under- side of the floor, compared to tubing only. This procedure eliminates any hot spots and provides a more consistent temperature at the floor surface. The installation procedure is identical to that of suspended tubing however, space the aluminum plates 3″ to 6″ apart for the best heat transfer coverage. The plates can be secured to the subflooring using staples, nails, or screws or they can be suspended just below the flooring using PEX-AL-PEX or PE-RT tubing. Note: Whether using aluminum heat transfer plates or suspending the tubing using pipe hangers, this installation requires that insulation be installed underneath the tubing to allow the heat energy to be transferred to the subfloor- ing and not downward below the tubing. A minimum of R-11 fiberglass insulation is required—even if the tubing is installed over a heated space. If the tubing is installed over a crawlspace, use insulation with a minimum R-19 value. The use of standard, unfaced insulation is adequate for either installation. 12.5 Radiant Wall and Ceiling Panels When altering the flooring is not an option for a radiant heating system, an alternative is to install either radiant wall panels or radiant ceiling panels. Because the principle theory behind radiant heating is to heat the objects in a room—not the air—both radiant wall and ceiling panels can achieve the same level of comfort as that of a radiant flooring system. Radiant wall and ceiling panels are considered low-mass systems due to the fact that the wall covering (such as drywall) has a lower thermal mass than that of concrete used in radiant flooring systems. Because of this fact, radiant wall and ceiling panels can respond much more quickly to changes in heat load require- ments and can heat up much faster, which makes them more attractive—espe- cially when considering using a temperature setback option. In addition, radiant wall and ceiling panels are much easier to retrofit than radiant flooring systems. 12.5.1 Installation of Radiant Wall and Ceiling Panels The installation procedure for radiant wall and ceiling panels is similar to that of radiant flooring systems. 1. The tubing is placed within the wall or ceiling cavity of an interior or exterior partitioned wall. Begin by drilling holes in the partition studs to route the supply and return tubing, Figure 12-32. Floor joists Insulation Heat transfer plates Uponor, Inc. Figure 12-30. With below-floor suspended tubing, heat is transferred from the bottom of the flooring and through the tubing to the floor above. Ultra-Fin Radiant Floor Heating System Figure 12-31. Aluminum heat transfer plates that are fastened to the tubing or directly to the subflooring can also be used for underfloor radiant heating. JuneJ/Shutterstock.com Figure 12-32. Begin the radiant wall or ceiling panel installation by first drilling holes in the partition studs to route the supply and return tubing.