Every week we will be including additional questions and informal UPC and UMC interpretations
- Can soft annealed copper which is enclosed in a wall cavity or above a ceiling be considered to be in a raceway?
- No, a wall cavity or ceiling in a building is not considered a raceway. Walls and ceilings are always subject to cutting or penetrating in some shape or form. A raceway is an enclosed channel designed expressly for holding the annealed copper.
- How many total hangers would be required on a 100' straight run of 10' lengths of No Hub Cast Iron pipe?
Per Table 313.3 of the 2018 Uniform Plumbing Code, Hubless Cast Iron, installed horizontally, shall be supported at every other joint unless over 4 feet, at which point it has to be supported at each joint. Additional requirements referenced in the footnotes include: 1) the adjacent joint must be supported within 18 inches of the joint; 2) a brace must be installed at least every 40ft. to prevent horizontal movement of the pipe; 3) a support must be installed at each horizontal branch connection and; 4) hangers may not be placed on the coupling.
A no-hub coupling, much like a threaded iron pipe coupling, consists of two joints. One half of the coupling creates a water tight seal for one piece of pipe or fitting while the other half serves a similar function for the connecting pipe or fitting. Per Table 313.3, a hanger for hubless cast iron needs to be installed within 18 inches of the joint. Since a no-hub coupling consists of two joints, a hanger would be required on both sides of the coupling.
- Does section UMC 510.1.3 Duct Installation, regarding sloping of exhaust ducts with "not less than 2 percent slope on horizontal runs up to 75 feet and not less than 8 percent slope on horizontal runs more than 75 feet", pertain only to the sloping of Type 1 grease exhaust ducts only, like it had in the previous edition of the code?
- No, Section 510.1.3 of the 2018 Uniform Mechanical Code does not pertain to Type 2 ducts. Section 510.1.7 of the 2018 UMC pertains to Type 2 duct systems. Type 2 exhaust duct used with a moisture related process such as a dishwasher would be required to drain back to the hood.
- Is it acceptable at any time to direct bury an "anode" style natural gas riser without an anode attached for cathodic protection?
- No. IAPMO lists “anode” type risers that meet DOT 192.281, 192.283, 192.375 and ASTM-D2513 CAT-1 specifications. Anode type risers not meeting those standards would need additional cathodic protection.
- Are flexible connectors allowed to be used in grease duct systems?
- Flexible connectors are not allowed in a grease duct in line exhaust fans inside the building. Additionally NFPA 96 sections 220.127.116.11 and 18.104.22.168 specifically prohibit the use of flexible connectors in grease duct systems. Sections 510.9.1.1 and 522.214.171.124 were previously added to the Uniform Mechanical Code in 2003 by the NFPA 96 task group.
- Does the UPC exception for shower receptors of 30 x 60” include a 1-piece shower enclosures of the same dimension?
- Yes. Section 408.6 of the 2018 UPC, Exception (2) permits the installation of a shower receptor having dimensions of not less than 30 inches in width and 60 inches in length. This allows the replacement of a bathtub with a walk in shower without meeting the minimum shower requirements found in Section 408.6. Listed one piece shower receptors meeting the dimensions found in Exception (2) would be acceptable.
- If a furnace compartment does not have a ceiling and is open to a ventilated attic, do we still need to bring in lower combustion air into the furnace compartment?
- Yes. The purpose of the upper and lower openings is to vent the appliance compartment. The hot air will rise and be replaced by the cooler lower combustion air opening. Furthermore, the code has a provision for the one opening method and the lower combustion opening would not be required so long as the provisions of Section 701.4.2 are met.
- Please explain IAPMO’s acceptance of a vacuum breaker as adequate protection against backflow on commercial garbage grinders with the water supply connected directly to the sewer. We are considering that an airgap be required for this installation in this area.
- Section 603.3.5 (2003/2006/2009) 603.4.4 (2012/2015/2018) prohibits direct connection of the potable water supply to sewer connected waste piping under any circumstances. The section later differentiates between a direct connection to drainage piping and the necessary introduction of a supply of flushing water to an open plumbing fixture or trap by means of a submerged inlet when protected by a properly placed vacuum breaker. A directly flushed siphon jet water closet is a common example. Here, a vacuum breaker protected flushometer valve delivers water to both the bowl flushing rim and the siphon jet in the bottom of the trap. IAPMO listed open hopper commercial food waste disposers require a continuous water supply while operating. The water usually enters the hopper through one or more strategically placed low inlets which, are properly located on the inlet side of the appliance trap when these inlets are protected by an approved vacuum breaker installed at a suitable height above the flood level rim of the hopper or scrap table, the garbage disposer meets the cross-connection control and water supply safety requirements of the UPC.
- Scenario: Commercial kitchen hood exhaust system, treated by a grease removal system or pollution control unit (scrubber).
Is the duct leaving the grease removal system or pollution control unit (scrubber) classified as grease exhaust or can it be treated as an environmental air exhaust or general exhaust?
- The duct leaving the pollution control unit is classified as grease exhaust even after being scrubbed, the exhaust would still fall under the requirements of “Grease Exhaust”. Pollution Control Units are generally listed to UL1978 and considered part of the exhaust duct system and not the exhaust termination. Section 209 of the 2012 Uniform Mechanical Code defines a grease duct as a containment system for the transportation of air and grease vapors that is designed and installed to reduce the possibility of the accumulation of combustible condensation and the occurrence of damage if a fire occurs within the system; while the definition of environmental air duct as found in Section 207 states that other than heating or air conditioning systems for human use would be considered environmental air.
- The Uniform Plumbing Code requires water heaters generating a glow or spark or flame capable of igniting flammable vapors to be installed in a garage, provided that the pilots and burners or heating elements and switches are at least 18 inches above the floor level in residential garages. The Code further states, “when such water heaters installed within a garage are enclosed in a separate, approved compartment having access only from outside of the garage, such water heaters may be installed at floor level, provided the required combustion air is also taken from the exterior of the garage.” Would the requirements of the Code apply to a water heater located in a room adjacent to a residential garage if the door of this room opens directly into the garage?
- The intent of the Code is to separate all sources of ignition from potential fuel sources. A door or opening which would permit the flow of fuel or vapors into the space where the water heater is installed would defeat this objective and be in violation of the Code.
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