IAPMO – Uniform Codes Spotlight | November 3, 2016

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2015 Guide to Important Code Changes

501.1 Applicability, 505.1 Water Heaters, and 505.4 Indirect-Fired Water Heaters

What Changed
501.1 Applicability. The regulations of this chapter shall govern the construction, location, and installation of fuel-burning and other
types of water heaters heating potable water, together with chimneys, vents, and their connectors. The minimum capacity for storage water heaters shall be in accordance with the first hour rating listed in Table 501.1(1). Design, construction, and workmanship shall be in accordance with accepted engineering practices, manufacturer’s instructions, and applicable standards and shall be of such character as to secure the results sought to be obtained by this code. No water heater shall be hereinafter installed that does not comply with the manufacturer’s installation instructions and the type and model of each size thereof approved by the Authority Having Jurisdiction. A list of accepted gas water heater appliance standards are referenced in Table 1401.1 501.1(2). Listed appliances shall be installed in accordance with the manufacturer’s installation instructions. Unlisted water heaters shall be permitted in accordance with Section 504.3.2.

505.1 Water Heaters. Water heaters deriving heat from fuels or types of energy other than gas shall be constructed and installed in accordance with the approved standards referenced in Sections 501.1(2), 505.3, or Section 505.4. Vents or chimneys for such appliances shall be approved types. An adequate supply of air for combustion and for adequate ventilation of heater rooms or compartments shall be provided. Each such appliance shall be installed in a location approved by the Authority Having Jurisdiction and local and state fire-prevention agencies.

505.4 Indirect-Fired Water Heaters. Indirect-fired water heaters shall comply with the applicable sections of the ASME Boiler and Pressure Vessel Code, or to one of the other applicable standards shown in Table 1401.1 Section 501.1(2). Each water heater shall bear a label in accordance with ASME requirements, or an approved testing agency, certifying and attesting that such an appliance has been tested, inspected and meets the requirements of the applicable standards or code.

Why It Changed
Section 501.1 was revised as the scope of the chapter encompasses all types of water heaters (ex: fuel gas-fired, oil-fired, electric, etc.), including applicable chimney, venting, and connector requirements The third sentence was struck out, but did not negate the requirement for water heaters to meet approved standards and be installed in accordance with manufacturer’s instructions. There is now a new Table 501.1(b) in this chapter that shows a list of accepted water heater appliance standards rather than referring to the Referenced Standards. Unlisted water heaters must meet the clearance requirements of Section 504.3.2.

Where listed water heaters are required, such appliances shall conform to the applicable mandatory reference standards, and should be listed to assist the end user in identifying water heaters that are approved based on material and performance requirements without having to search throughout Table 1701.1. Adding mandatory reference standards to the body of the code was one of the recommendations that were made to the Technical Committee by the Standards Task Group.

Oil-fired water heaters are to be listed to UL 732, but as required by UL 732 and Section 505.3, should be installed in accordance with NFPA 31.

Section 505.1 was also modified to provide correlation with the applicable non-fuel gas standards referenced in Section 501.1 (UL 732, UL 174, or UL 1453), Section 505.3 (NFPA 31), or Section 505.4 (ASME Boiler and Pressure Vessel Code).

Section 505.4 was revised to provide correlation with the applicable standards referenced in Section 501.1.

What It Means To Me
Water heaters that are listed comply to referenced standards and are in compliance only if they are installed per the manufacturer’s installation instructions. Due to the number of different
manufacturers it is imperative that the installation instructions for the particular water heater be followed. The installer should leave these instructions with the water heater for the home owner and for the inspector to verify these were heeded.

If the water heater is not installed properly the manufacturer may void any warranty if problems should arise from an improper installation. Furthermore, deadly consequences can occur from not installing the mandatory safety features.

Please note that some items are “recommended” by the manufacturer and not necessarily mandatory. These instructions usually reference that the installer “comply with local code requirements.”

Pressure Vessels nameplates for hot water storage tanks over 120 gallons will contain a “U” symbol which stands for “Unfired Pressure Vessel.” Another symbol you will encounter is “HLW“, where ‘L” is inside the top part of “H” in “HLW,” and “W” is inside the bottom part of “H” in that “HLW” symbol. The rules in “Part HLW” of the ASME Code apply to water heaters and water storage tanks with corrosion resistance for supplying potable hot water. You will see the “U” symbol if the nameplate is welded to the tank (on the side), and “HLW” is just a label attached on the side of the tank.


The 2015 Guide to Important Code Changes is available for purchase here:

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