UNFORM CODES QUESTIONS & ANSWERS

Every week we will be including additional questions and informal UPC and UMC interpretations

1. What is the UMC definition of Factory Made?
2. What is the definition of an Air Connector?
3. Does the arbitrary 5' length include the connector?
- 1. There is not a specific definition of Factory Made ductwork in the 2015 Uniform Mechanical Code. All ductwork not made onsite or mass produced ductwork could be considered factory made. Under the provisions of section 603.4 of the UMC all Factory Made must comply with UL181. The broad range of products covered under this standard are often of proprietary design. They typically come in flexible or rigid lengths or in sheets or boards for field assembly into a rigid duct. Their composition is limited to metal or mineral materials. Nonmetallic or organic materials may only be used as “binders, adhesives, sealants, or finishes.” The manufacturer must mark every portion of a Factory Made air duct system to show compliance with the standard. The duct system must be installed in accordance with the terms of its listing and the installation instructions shipped with the duct material. The SMACNA-2006 HVAC Duct Construction Standard, which includes directions for the installation of factory-made air ducts, should be consulted. The manufacturer’s instructions should include a complete and detailed description of the methods to be used for joining and splicing the ducts. The materials used for this purpose must comply with the requirements of the referenced standard for closure systems found in UL 181A and UL 181B.
  
  2. An Air Connector is a short length of flexible non-porous material that is inserted between metal ductwork and a metal air diffuser (or air register) to prevent the transmission of vibration between these components of the system.
  
  The markings on the material will identify it as either a flexible air duct or a flexible air connector. Both the flexible air duct and flexible air connector must comply with the requirements of UL 181 for Class 0 or Class 1. Flexible air ducts require more extensive testing (flame-penetration, puncture, and impact tests) than flexible air connectors. This difference in testing is what determines the markings on the material and whether or not it is classified as a flexible air duct or a flexible air connector.
  
  3. This length limitation is not arbitrary. The length limitation of section 603.4.1 in the 2015 UMC applies to factory made flexible air duct and connectors in general with the exception being residential occupancy installations. In this particular section the limitation refers to both the connector as well as the duct. Neither may exceed 5 feet except in a residential occupancy.
The question centers around the number of fixture units to be used in designing a drain when a kitchen (residential) sink and a dishwasher drain into the same drain line. Does Table 7-3 (2003/2006/2009) Table 702.1 (2012/2015/2018/2021) require the design fixture units to be two or a design total of four (two plus two) fixture units?
- When a residential dishwasher drain discharges through a trap that also receives the drain discharge of a residential kitchen sink, the total fixture unit count is two. When connected jointly through a single trap and trap arm, the potential combined load is still assigned two fixture units, a consequence of the flow limitations through a one and one half inch trap. Residential sinks or dishwashers, when connected to separate traps, each impose a two fixture unit load on the plumbing system and the total fixture unit count is four.
Do liquefied petroleum gas (LPG) facility appurtenances include LPG piping and shutoff valves serving an appliance?
- No. LPG facilities as defined in Section 1303.5 consist of the LPG storage tanks, regulators and associated equipment. The piping, appliances, water heaters, and associated shutoff valves are not the facilities but are part of the fuel gas systems.
What is the reasoning behind Polyethylene pipe not being allowed to be used as building drain and only allowed as building sewer?
- PE was added to Table 701.2 in 2015 for the building sewer only. The reason that it is not permitted for DWV is because there are no PE fittings approved for DWV applications. The standards for PE fittings apply to socket type, butt fusion and electrofusion fittings intended for water supply applications as referenced in Table 604.1 of the UPC.
Is the piping required in the UMC to be secured (strapped) to the supports to maintain alignment?
- Yes. Strapping or securing the pipe to the support is necessary to maintain alignment as required by the code.
Do water treatment units require cross-connection control before the potable water enters the unit?
- UPC Section 602.3 requires segregation of potable water from contaminated or polluted water. If the water downstream of a water treatment unit meets the standards which define potable water, it is presumed that there has been no contamination or pollution by virtue of the treatment process; consequently, backflow protection is unnecessary. If the water downstream of a water treatment unit is unable to meet potable water standards, then an appropriate backflow preventer must be installed ahead of the treatment unit.
Is it allowed to reduce the size of a vent connector for a fan assisted appliance if all the requirements of UMC Section 803.0 are followed?
- Yes, if all the requirements of Section 803.0 are met, unless the installation would not conform to the conditions of the listing of the appliance per Section 304.1 (2003/2006), 303.1 (2009) and 303.2 (2012/2015/2018/2021).
Are saddle valves prohibited by the UPC?
- The UPC (Uniform Plumbing Code) does not specifically address the use of saddle valves on potable water systems. Section 301.1.1 (2003/2006/2009) 301.1 (2012) 301.2 (2015/2018/2021) however requires all pipe, pipe fittings, traps, fixtures, material, and devices used in a plumbing system to be manufactured to applicable standards, certified by a third party listing agency and submitted to the Authority Having Jurisdiction for approval for use. Section 311.5 (2003/2006/2009), 310.5 (2012/2015/2018/2021) prohibits any piping connection that obstructs or retards the flow of water. A needle protruding into a water pipe would certainly obstruct the flow of water within the pipe. Not only does the needle obstruct or retard the flow of water, but so does the burrs created when piercing or drilling the pipe. Anything protruding into the flow line would create turbulence which can cause damage to the pipe and fittings in the system.
Does the UMC regulate diesel engine fuel-burning generator exhaust piping from its connection at the equipment to its termination point? Our jurisdiction assumes that the exhaust piping, as stated, is not regulated by the UMC. Is this correct?
- Yes, Section 925.0 states that gas engines shall conform to NFPA 37, Standard for the Installation and Use of Stationary Combustion Engines and Gas Turbines. There are further requirements found in Section 7.10 of NFPA 110, Standard for Emergency and Standby Power Systems, which is referenced by some Fire Codes.
A replacement water heater in a residence was installed inside a utility room, located approximately 12 to 15 feet from the building exterior. The building construction is a conventional raised floor with a crawl space. The water heater is installed in a pan. The temperature and pressure relief valve terminates into the pan which is drained into the crawl space. The Code states that the pan shall drain to an approved location. Can the pan drain into the crawl space, as opposed to being piped to the building exterior?
- Discharge piping from any source may not empty into the crawl space beneath a building. All discharge piping shall terminate outside the building or to an approved receptor located within the building. The drain must terminate in a visible location. Note: The pan serving the water heater is not an approved receptacle for the T&P valve. The Code does not intend that a 3/4 inch pressure pipe (relief valve) be discharged into a receptacle which is equipped with a 3/4 inch gravity drain (drip pan).