No the 2021 Uniform Mechanical Code does not contain provision for tempering the makeup air for a kitchen exhaust hood. The Authority Having Jurisdiction may adopt Appendix E of the 2021 UMC or other energy standard that requires the control of enthalpy/tempering for make up air.
1. Yes. A vertical pipe has a much higher carrying capacity than a horizontal pipe. Table 703.2, limits the carrying capacity of a vertical stack to one-third of the maximum flow at full velocity, which aids in the control of air pressures within the stack. Once the stack has reached the listed limitations in Table 703.2, a horizontal offset may be installed. To insure adequate air circulation in the drainage system as required in Section 901.2, the horizontal offset must be long enough to enable the effluent to reach normal flow depending on grade, after the hydraulic jump, before continuing as a vertical stack. 2. Yes. See explanation in #1.
No. Section 409.4 of the 2021 Uniform Plumbing Code specifically states that “the maximum hot water temperature discharging from the bathtub and whirlpool bathtub filler shall be limited to 120°F (49°C). The maximum temperature shall be regulated by one of the following means: (1) A limiting device conforming to either ASSE 1070/ASME A112.1070/CSA B125.70 or CSA B125.3. (2) A water heater conforming to ASSE 1084.”
Yes, a listed Type 2 dryer equipped with a lint filtering system would meet the minimum standards of Section 504.4.3.1 (3) of the 2021 Uniform Mechanical Code. The manufacturers listing of the equipment might require other means for lint control such as an exhaust fan interlocked with dryer operation and include cleanouts within the exhaust piping.
The UPC requires all floor mounted fixtures (floor drains, shower drains, floor sinks, etc.) to be "suitably flanged," which equates to be "double-flanged." The top flange provides sufficient surface area that is large enough to accommodate strainer openings (equivalent to the area of the tailpiece). The bottom flange is a designed feature and is intended to prevent leakage which passes the top flange from wetting the ceiling of the floor level below. Shower receptors installed at any floor level above the "slab on grade" level are required the have an additional clamping ring on the bottom flange. This ring allows the lining material to be secured and pitched "to the weep holes in the subdrain.
Yes it is allowed to terminate an environmental exhaust duct eight feet above grade, but not above a public walkway. The intent of the code is to prevent exhaust air from exhausting directly on the walkway users so they are not subjected to the fumes or other by-products. The 2021 Uniform Mechanical Code states that the environmental duct shall not discharge onto a public walkway. The last sentence of section 502.2.1 clearly states no discharge onto a public walkway. Environmental ducts have situations that could cause action upward and downward. No allowable distance is given for discharge onto a public way.
Yes, a sediment trap is required on all gas appliances, including water heaters, where one is “not incorporated as part of the gas utilization equipment.” Sediment traps are not required on appliances such as “illuminating appliances, ranges, clothes dryers, decorative vented appliances for installation in vented fireplaces, gas fireplaces, and outdoor grills.” For some reason Code language is sometimes written in the negative declaration. 1212.9 (2021) states which appliances do not require sediment traps at installation. Water heaters and furnaces are not included in that list; consequently, a sediment trap is required for residential water heaters.
Table 1102.3, “Refrigerant Groups, Properties and Allowable Quantities,” is appropriate for determining compliance with the maximum quantities allowed in a refrigeration system. When the code is silent in its clarification of a particular requirement, the Administrative Authority must be responsible for the enforcement and clarification. Proper research and information collection is of utmost importance when variances in code provisions are required. The standards located in Chapter 17, Part II, UMC (2003/2006/2009/2012/2015/2018/2021) direct the code user to the proper standard for refrigerants. ASHRAE 34 is a referenced standard and should be used as appropriate. Note: The 2021 Uniform Mechanical Code includes the most current refrigerant tables from ASHRAE 34 and includes many of the new refrigerants. At the time of printing, the safety group designation is listed but the quantitative values for the refrigerants used in your example were not available and not included. Due to the constant and rapid development of new refrigerants, it will not contain all of the maximum quantity values; therefore, the standard should be addressed when they are not shown.
The sections are as follows 310.6 Dissimilar Metals, 605.16 Dielectric unions, 605.17 Joints Between Various Materials and 1210.1.3 Protection Against Corrosion. These sections are requirements for several different types of installations.
No, this requirement is specifically applicable to section 1005.2 of the 2021 Uniform Mechanical Code which pertains to boilers and pressure vessels and the termination of their listed pressure relief valves. Safety and relief valves shall not discharge so as to be a hazard, a potential cause of damage or otherwise a nuisance. High pressure must be vented to the outside of the structure. Low pressure can discharge to the drainage system; the installation must conform to the Uniform Plumbing Code. The termination of pressure steam valves should be consistent with UMC 1005.4 due to the hazard potential created by discharge of steam or as specified by the manufacturer of the valve and or boiler. Additionally sections 904.6 and 904.6.1 of the 2021 UMC also deal with relief valve termination. Section 904.6.1 when applied, should be cross referenced with section 1005.3 (Splash Shield) that states any operating temperature exceeding 212º F the discharge piping needs to be installed with a splash shield or centrifugal separator.
If you have a code question you would like answered in this forum, please click here to submit question
IAPMO members may view the complete online Answers & Analysis content HERE