Copyright Goodheart-Willcox Co., Inc. 246 Hydronic Heating: Systems and Applications 12.4 Radiant Floor Piping Configurations There are many piping configurations available for radiant heating installations. The most common method is radiant floor heating, which can be classified as either wet radiant hydronic systems or dry radiant hydronic systems. Wet systems include: ■ ■■ Slab on grade ■ Concrete or gypsum thin slab Dry systems include: ■ ■■ Above-floor prefabricated panels ■ Below-floor staple-up or suspended tube systems 12.4.1 Slab-on-Grade Radiant Floors The slab-on-grade radiant piping configuration is very popular and is used primarily with new construction. The term slab-on-grade means that a layer of CODE NOTE Mechanical Code Standards for Radiant Piping Materials Both crosslinked polyethylene (PEX) tubing and raised temperature polyethylene (PE-RT) tubing are recognized in all major building codes for use with hot-water and cold-water distribution applications, water service lines, and for radiant floor heating systems. Code standards such as the International Residential Code (IRC), International Plumbing Code (IPC), International Mechanical Code (IMC), as well as the Canadian Standards Association (CSA), outline the use of these radiant piping materials through tables based on ASME, ASTM, and CSA standards. The installer must determine which codes are applicable to the specific proj- ect and must ensure compliance with all local, state, and federal code regulations and standards. Codes are constantly reviewed and updated. The use of PEX tub- ing has been adopted in the model codes since 1993. Grigvovan/Shutterstock.com Figure 12-16. Socket fusion is a method of joining piping such as PE-RT by heating the pipe and fusing it together. DID YOU KNOW? HDPE for Geothermal Ground Loops High-density polyethylene piping (HDPE) is commonly used for geothermal ground loops and can be connected using heat fusion. This process melts the piping and joins it together using special tools. HDPE piping can be joined together using butt splicing or with special fittings or sockets of the same material.