From the 2021 UPC Illustrated Training Manual, Chapter 5, WATER HEATERS
509.8.2 Direct-Vent Appliance. The clearances for through-the-wall direct-vent terminals shall be in accordance with Table 509.8.2. The bottom of the vent terminal and the air intake shall be located not less than 12 inches (305 mm) above finished ground level. [NFPA 54:12.9.3]
This section permits the vent terminals of direct vent appliances to be located much closer to air inlets than permitted for appliances that are not direct-vented. Studies have shown that vent gases from direct-vent appliances disperse rapidly upon leaving the vent terminal, even when the terminal is located under an open window; however, a window is unlikely to be open when heat is needed. The section also specifies the location of the exit terminal of direct-vent appliances. All of these locations are shown in Figure 509.8.
The 2021 Uniform Plumbing Code Illustrated Training Manual is available for purchase here.
(This is not to be considered the official position of IAPMO, nor is it an official interpretation of the Codes.)
IAPMO develops and publishes the Uniform Plumbing Code®, the most widely recognized code of practice used by the plumbing industry worldwide; Uniform Mechanical Code®; Uniform Swimming Pool, Spa and Hot Tub Code®; and Uniform Solar Energy, Hydronics and Geothermal Code™ — the only plumbing, mechanical, solar energy and swimming pool codes designated by ANSI as American National Standards — and the Water Efficiency Standard (WE-Stand)™. IAPMO works with government, contractors, labor force, and manufacturers to produce product standards, technical manuals, personnel certification/educational programs and additional resources in order to meet the ever-evolving demands of the industry in protecting public health and safety.
Last modified: August 17, 2023