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On July 8, 2020, the San Diego Air Pollution Control Board (SDAPCD) adopted a major set of rules and rule amendments intended to control oxides of nitrogen (NOx) emissions from fuel combustion sources including boilers, process heaters, steam generators, and water heaters. The new and amended rules are summarized as follows:

  • New and Retroactive Permitting: A Rule 11 amendment reduces the size threshold at which units of these types are required to obtain air permits or registrations. Units fired exclusively by natural gas were previously exempt from permitting requirements if rated under 5 million Btu per hour (MMBtu/hour); the threshold is reduced to 2 MMBtu/hour, effective April 1, 2021. This change will require retroactive permitting actions for many existing natural gas burning sources at industrial and commercial facilities. The change in the permitting threshold is intended to facilitate monitoring compliance with the new Rule 69.2.2 discussed below.

  • Medium Fuel-Burning Units: A new Rule 69.2.2, effective July 1, 2021, will further restrict NOx emissions from new and existing fuel combustion units to reduce their impact on the area's ozone nonattainment status and require annual tune-ups of larger new and existing combustion equipment. This will require all new and existing boilers, process heaters, and steam generators with a heat input rating of 2 to 5 MMBtu to apply for a District permit or registration by July 1, 2021; the remaining requirements take effect by July 1, 2021 for new units, and January 1, 2022 for existing units.

    The rule requires all boilers, process heaters, and steam generators with a heat input rating of 2 to 5 MMBtu/hour to be tuned up by July 1, 2022 and annually thereafter. The tune-ups require measurement of exhaust NOx and CO concentrations using a portable instrument following ASTM Test Method D6522. Recordkeeping of tune-ups would be required for compliance demonstration. Additionally, new boilers, process heaters, and steam generators of the same sizes will be limited to exhaust concentrations of NOx of 30 ppmvd at 3% oxygen for gaseous-fueled sources and 40 ppmvd at 3% oxygen for liquid-fueled sources. Emissions of CO will be limited to 400 ppmvd at 3% oxygen for all fuels in order to ensure that NOx control is not achieved at the expense of CO emissions. The sale of new affected equipment will be illegal in San Diego County unless the manufacturer submits a certification of compliance in advance to SDAPCD, on a per model number basis, at least 30 days in advance of offering any affected unit for sale. Units capable of firing both gaseous and liquid fuels will be subject to additional fuel usage monitoring and recordkeeping requirements.

  • Small Fuel-Burning Units: A Rule 69.2.1 amendment extends its applicability to sources of these types with heat input ratings as small as 75,000 Btu/hour and up to 2 MMBtu/hour. The previous version of the rule only covered units from 600,000 Btu/hour to 2 MMBtu/hour. These units will remain exempt from permitting and registration requirements, however, effective July 1, 2021, new units in the 75,000 Btu/hour to 2 MMBtu/hour range must be manufacturer-certified to SDAPCD for compliance with this rule's emission limits, which are generally referred to as the “ultra-low NOx emission level.” Alternatively, the manufacturer may submit to SDAPCD a certification that meets the requirements of the equivalent South Coast Air Quality Management District Rule 1146.2. Certification must be submitted at least 30 days before the make and model in question may be offered for sale, sold, or installed within San Diego County. Certified units must be marked as such on the outer carton and nameplate. Testing to support the certification submittal must be conducted in accordance with rule procedural requirements. Implementation of this rule will new impact installations of a very large number of sources, including residential and commercial equipment such as:
    • All tank-style water heaters except some light-duty residential units (these are typically 40,000 Btu heat input rating)
    • Nearly all tankless water heaters
    • Nearly all pool heaters
    • Nearly all boilers

For more information regarding the rules and amendments, or for assistance in evaluating the new permitting and emission control requirements, please contact us at 949.567.9880.