Guidance regarding ultra-low NOx water heaters (H.B. 313 and R307-230).
Background
During the 2025 General Session, the Utah State Legislature passed H.B. 313, Construction Industry Amendments, which amended Utah State Code 19-2-107.7 to limit the applicability of the nitrogen oxide emission limits for natural gas-fired water heaters set in 15A-6-102 from applying statewide to only applying in ozone and PM2.5 nonattainment areas in the state, as shown in the figure below. This law goes into effect on July 1, 2025.
On May 7, 2025, the Utah Air Quality Board proposed an amendment to administrative rule R307-230 to align with the statute and to reflect the new applicability limitations required by H.B. 313. We anticipate that a final rule will be recommended for adoption by the Board in early August 2025.
Detail
Utah State Code 19-2-107.7 disallows the sale or purchase of a water heater that exceeds the natural gas-fired emission limit set in 15A-6-102 with the intent to install that unit in Utah, as stated below:
A person may not sell or purchase a natural gas-fired water heater that is manufactured after July 1, 2018 with the intent to install it in Utah if the natural gas-fired water heater exceeds the applicable nitrogen oxide emission rate limit set in Title 15A, State Construction and Fire Codes Act.
Units that comply with these limits are more commonly referred to as “ultra-low NOx” water heaters. H.B. 313 amends Utah State Code 19-2-107.7 by limiting that section to only applying to “ozone nonattainment area or PM2.5 nonattainment area” as defined in 19-2-107.7(1) (b) and (c ). These nonattainment areas are generally located along the Wasatch Front and in the Uinta Basin, but do not conform to city, county, ZIP Code, or other typical geographic boundaries. They are instead established based on a combination of attributes related to air quality emission sources and their associated impacts. As a result, UDAQ has developed a web-based tool to assist purchasers, installers, and sellers of water heaters in identifying whether an ultra-low NOx unit is required at a given installation site.
The requirement for an ultra-low NOx water heater applies to you if you are selling or purchasing a unit for installation in an ozone or PM2.5 nonattainment area in Utah. Affected parties may include:
- Home and business owners purchasing a water heater for installation within a nonattainment area,
- Plumbers or other equipment installers selling and/or installing a water heater within a nonattainment area, or
- Sellers of water heaters for installation within a nonattainment area.
If you fall into one of these categories, we encourage you to use the web-based tool described above to determine whether an ultra-low NOx water heater is required at the installation site.
More Information
If you have questions or need more information, please contact Chad Gilgen ([email protected]).