Written by IAPMO 2:54 pm Answers and Analysis Q&A

Answers & Analysis | First Quarter 2024

Taken from the Online Editions of the UPC & UMC Answers & Analysis

SUBJECT: Temperature Limitation, Shower and Tub-Shower Control Valves 

SECTION: 406.3.2 (4) (2021 UPC) 

1. Why is this limited to a water heater conforming to ASSE 1084?

2. Why isn’t ASSE 1082, performance requirements for water heaters with integral temperature control devices for hot water distribution systems, also an option? 

1. A water heater conforming to ASSE 1084, as found in Section 408.3.2 of the Uniform Plumbing Code (UPC), is a point of use water heater. Per Section 1.2.1 of ASSE 1084, “This water heater is intended to supply tempered water at point of use in order to reduce the risks of scalding.” These devices limit water temperature to a maximum of 120°F. 

2. A water heater listed to ASSE 1082, per Section 1.2 of the standard, “is for water heaters that control the outlet temperature to specific limits and are installed within the hot water distribution system but not at point-of-use.” Water heaters listed to this standard limit water temperature to a maximum of 125°F, which exceeds the water temperatures permitted by Sections 407.3, 408.3.2, 409.4 and 410.3 of the UPC

SUBJECT: Control Valves  | SECTION: 606.5 (2021 UPC) 

1. Does the term “appliance” used in the first sentence refer to an appliance as defined in Chapter 2 or is it referring to a water supplying fixture? 

2. If it is referring to a water supplying fixture does that include in-wall tub/shower valve, hose bibbs, washing machine stops and wall-mounted fixtures such as kitchen faucets, pot fillers and lavatory “vessels” fixtures, which are typically hard piped are required to have control stops? 

3. When the water distribution system is of parallel design does it require valves on each branch of the manifold even when a particular branch may not serve a traditional slip joint supplied fixture (i.e. shower fixture or hose bibb)? 

1. Yes. The term appliance, referenced in Section 606.5 of the Uniform Plumbing Code, is a plumbing appliance as defined in Section 218. 

2. No. By definition, tub/shower valves, hose bibbs, washing machine stops, etc. would be considered fixture fittings*. 

3. Per Section 606.5, parallel water distribution systems are required to have a shutoff valve for each fixture or appliance either at the manifold or at the fixture or appliance. When manifolds are located in areas that are not readily accessible, a valve is required at each individual fixture or appliance. When installing a parallel water distribution system, a valve is required on every fixture or appliance, regardless of the type of joint used to connect the fixture or appliance to the water distribution system. 

*Section 208.0 Fixture Fitting – A device that controls and guides the flow of water. 

SUBJECT: Termination of Type II Hood Exhaust System  | SECTION: 519.5 (2021 UMC) 

1. May a Type II dishwasher exhaust vent terminate less than 3 feet from a roof access hatch? 

2. May an environmental exhaust terminate less than 3 feet from a roof access hatch? 

3. Would a building opening include a roof access hatch? 

1. No. Section 519.5 (2) of the Uniform Mechanical Code states that a Type II Hood Exhaust horizontal termination shall not terminate less than 10 feet from operable openings to buildings. Section 519.5 (1) of the UMC also states that if a Type II Hood Exhaust outlet is a horizontal termination the exhaust termination shall be at least 40 inches above the roof’s surface, a minimum distance of 10 feet from the property line, and the exhaust flow shall be directed away from the roof surface. Additionally, kitchen exhaust air is listed as Class 2 Air, which is “…inappropriate for transfer or recirculation to spaces used for different purposes.” 

2. No. Section 502.2.1 of the UMC states that environmental air ducts shall terminate not less than 3 feet from openings into the building. 

3. Yes, this is correct. While the UMC does not specifically provide a definition for a roof opening hatch, OSHA does provide a definition of opening — a gap or open space in a wall, partition, vertical walking/working surface or similar surface in which an employee can fall to a lower level. Therefore, a roof hatch would be considered to be an operable opening as per section 519.5 (2) of the UMC


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: March 20, 2024