Every week we will be including additional questions and informal UPC and UMC interpretations
- Is the foot valve in a well considered to be a device requiring an expansion tank?
- No, although a foot valve is a device that could prevent pressure relief through the building supply, private water well systems are normally designed to pump water through a storage tank which stabilizes the pressure and operates the same as an expansion tank. An expansion tank, as required by Section 608.3, is not necessary in a private well water system which has a storage pressure tank between the foot valve and the building piping system.
- UPC Section 601.3 (2003/2006/2009), 417.5 (2012/2015/2018/2021) states that “faucets and diverters shall be connected to the water distribution system so that hot water corresponds to the left side of the fittings.” There is no mention of where the person stands in relation to the fittings. If I were standing on the outside of an island tub, where should the hot be? I can operate the faucet from outside or inside the tub.
- The left side of a faucet is determined when the operator is positioned inside of the fixture (tub, shower, etc.) facing the control valves.
- I would like to know what is the minimum distance from windows of a residential building to the point where the exhaust air from commercial clothes dryers is discharged to the atmosphere.
- Commercial dryer exhaust meets the definition of environmental air. The termination for commercial dryers must be in compliance with Section 504.5 (2003/2006/2009/2012) 504.4 (2015/2018/2021) or in accordance with the listing and the manufacturer’s installation instructions, whichever is more restrictive. Section 504.5 requires that environmental air duct exhaust terminate a minimum of 3 feet from property lines and openings into buildings.
- Would the size of the water supply system be able to control thermal expansion without installing a thermal expansion tank?
- There is no provision in UPC Section 608.3 which allows thermal expansion to be controlled by the size of the water system.
- In the UMC, is the correct spacing between combustion air openings and environmental duct openings 4 feet?
- No, 3 feet from building openings is the correct minimum spacing per UMC Section 504.5.
- Does a cleanout, located inside a cabinet and which requires opening the hinged cabinet door and removing a drawer, meet the accessibility requirements of UPC Section 707.9 (2003/2006) 707.8 (2009/2012/2015/2018/2021)?
- Yes, as defined in Section 203.0 of the UPC, “Readily accessible means direct access without the necessity of removing any panel, door, or similar obstruction”. Opening a cabinet door is considered readily accessible. See also 707.10 (2003/2006), 707.9 (2009/2012/2015/2018/2021)
- Is it correct that a building of wood frame construction does not allow a non-ducted return (plenum above the T-Bar ceiling)?
- No, Section 602.1 of the 2021 Uniform Mechanical Code states that “concealed building spaces or independent construction within buildings shall be permitted to be used as ducts or plenums”.
According to this section of the code, a building of wood frame construction would be allowed to use the space above the T-bar ceiling as the duct or return plenum. However, Section 602.2 of the 2021 UMC clearly states that combustible material exposed within ducts or plenums shall meet minimum flame-spread index and smoke-developed rating requirements. The requirement for what type of material a plenum may be constructed of is found in the building code. There are buildings of combustible construction that would allow for combustible plenums. The intent is to allow plenums to be constructed of materials that are consistent with the materials that are allowed for the building construction.
In summation, a plenum constructed of combustible materials shall meet minimum flame-spread index and smoke-developed ratings.
- Does UPC Section 420.0 (2003) 418.0 (2006/2009) 409.4 (2012/2015/2018/2021) apply to bathtubs and roman tubs with no shower?
- No. Section 420.0 (2003) 418.0 (2006/2009) 409.4 (2012/2015/2018/2021)clearly states that only showers and tub-shower combinations fall under this requirement. Section 414.5 was added in 2009, 408.3 (2012/2015/2018/2021) and now requires bathtub and whirlpool tub fillers to limit hot water to 120º F by a device that conforms to ASSE 1070 or CSA B125.3
- For makeup air fans where the exhaust hood controls automatically shutoff the power to the makeup air fan on detection of fire under the hood or the building fire alarm panel is in alarm, are additional duct smoke detectors required by the UMC?
- No, this application could be consistent with 2021 Uniform Mechanical Code Section 609.1 exception number (1). As long as this exhaust is controlled by the exhaust hood, no additional smoke detectors are needed. Otherwise any and all independent air-moving systems including a makeup air unit supplying air in excess of 2000 cfm to an enclosed space within a building are required to have an automatic shutoff.
- May CPVC piping be used for hot water distribution "outside" the building?
- IAPMO Installation Standard IS 20 very specifically defines CPVC as suitable for "hot and cold, water within buildings." Section 604.1 allows the use of CPVC for "cold water distribution systems outside a building." Nonetheless, each local Authority Having Jurisdiction has the prerogative of allowing CPVC for hot water distribution outside of the building when all concerns have been addressed by an alternative method of installation.
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