May 21, 2026
From the 2024 UPC Illustrated Training Manual, Chapter 8 – INDIRECT WASTES
814.2 Condensate Control. Where any equipment or appliance is installed in a space where damage is capable of resulting from condensate overflow, a drain line shall be provided and shall be drained in accordance with Section 814.1. An additional protection method for condensate overflow shall be provided in accordance with one of the following:
(1) A water level detecting device that will shut off the equipment or appliance in the event the primary drain is blocked. Such detecting device shall be in accordance with the manufacturer’s installation instructions.
(2) An additional watertight pan of corrosion-resistant material, with a separate drain line, installed beneath the cooling coil, unit, or the appliance to catch the overflow condensate due to a clogged primary condensate drain.
(3) An additional separate drain line at a level that is higher than the primary drain line connection of the drain pan.
(4) An additional watertight pan of corrosion-resistant material with a water level detection device installed beneath the cooling coil, unit, or the appliance to catch the overflow condensate due to a clogged primary condensate drain and to shut off the equipment.
The additional pan or the additional drain line connection shall be provided with a drainpipe of not less than 3/4 of an inch (20 mm) nominal pipe size, discharging at a point that is readily observed.
When equipment or appliances are installed in a space where damage may result from a blocked primary condensate drain, an overflow or secondary drain must be provided. There are several ways to meet this requirement and the appropriate method is mostly dependent on the design of the equipment or appliance. If the equipment or appliance is equipped with an overflow (secondary) connection, it is to be piped to discharge to a conspicuous location so the public would be alerted that the primary drain is stopped. Approved locations could vary with jurisdictions but would include a point above a showerhead in a bathtub or shower or outdoors above an exterior window. If no additional separate drain outlet is provided, a watertight, corrosion-resistant pan is to be installed under the equipment or appliance to collect the overflow. The pan should be piped similarly to the secondary drain pipe. The pan drain pipe shall be a minimum . inch, discharging at a point that can be readily observed.
From the 2024 UMC Illustrated Training Manual, Chapter 8 – CHIMNEYS AND VENTS
802.4.1 Plastic Piping. Where plastic piping is used to vent an appliance, the appliance shall be listed for use with such venting materials and the appliance manufacturer’s installation instructions shall identify the specific plastic piping material. The plastic pipe venting materials shall be labeled in accordance with the product standards specified by the appliance manufacturer or shall be listed and labeled in accordance with UL 1738. [NFPA 54:12.5.2]
Before the introduction of high-efficiency gas utilization equipment (90+ percent efficiency), plastic piping was prohibited as a vent material. High-efficiency (Category IV) appliances reduce vent temperatures, resulting in condensate formation. As accumulation of condensate became a source of corrosion of metal vents, plastic piping became the preferred material. Plastic vent materials are required to be used for listed gas utilization equipment only when specified in the manufacturer’s instructions.
(This is not to be considered the official position of IAPMO, nor is it an official interpretation of the Codes.)
IAPMO
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: May 28, 2026