Boilers emit air contaminants including oxides of nitrogen, carbon monoxide, volatile organic compounds, oxides of sulfur, particulate matter and toxic air contaminants. All boilers with maximum heat inputs equal to or greater than 5 million Btu per hour (MMBtu/hr) require permits to operate from the District. In addition, units capable of being fired on liquid fuel with a maximum heat input ratings equal to or greater than 1 MMBtu/hr require permits to operate.
The District accepts applications for boilers above 2 MMBtu/hr and less than 5 MMBtu/hr. These “medium size” boilers will require registration or permitting, even if fired exclusively on gaseous fuels. For registering these 2 to 5 MMBtu/hr boilers, see our registration page.
Boilers operate on a variety of fuels, including natural gas, propane or fuel oil. Boilers can produce hot water or steam. Common techniques for controlling emissions include using low NOx burners, flue gas recirculation, other combustion modifications, or exhaust aftertreatment with processes such as selective catalytic reduction (SCR).
In accordance with the Small Boilers Rule section (e), manufacturers of new small boilers, installed, manufactured or sold on or after July 1, 2021, must certify each model offered for sale in San Diego County. Manufacturers must email the District's Compliance Division at least 30 days before the unit model is offered for sale, sold, or installed a signed, dated, and attested Certification Statement for each applicable model of boiler, process heater, steam generator, or water heater. The Certification Statement shall contain the following:
1. Name and address of manufacturer
2. Brand name
3. Model number
4. Description of the model unit being certified, including burner type
5. Heat input rating as specified on the nameplate, and
6. Oxides of nitrogen and carbon monoxide emission test results of each model being certified.
The medium boilers rule requires a similar certification process:
(f)(1) Except as provided in Subsection (b)(3), a manufacturer of any new unit to be offered for sale or sold for use within San Diego County shall submit to the Air Pollution Control Officer an application to certify that each model of boiler, process heater, or steam generator subject to the requirements of Section (d) Standards complies with the provisions of this rule.
(i) The application shall be signed, dated, and attested to the accuracy of all information by a representative of the manufacturer.
(ii) Except as provided in Subsection (f)(1)(iii), the application shall be submitted at least 30 days before the unit model is offered for sale, sold, or installed within San Diego County.
(iii) For any unit model that has not been certified by the Air Pollution Control Officer before the sale of the unit:
(A) The manufacturer or its representative shall conduct an initial source test within 30 days of unit installation in accordance with Subsections (i)(1)(i) or (ii), and
(B) The application shall be submitted within 30 days of conducting theinitial source test.
(iv) The application shall include:
(A) Brand name,
(B) Model number,
(C) Heat input rating as specified on the nameplate, and
(D) Oxides of nitrogen and carbon monoxide emission test results of each model being certified.
(2) The certification application shall include a demonstration that the boiler, process heater, or steam generator model was tested in accordance with Section (i) Test Methods and found to comply with the requirements of Subsection (d)(1).
(3) After completing review of the application for certification and source test report, the Air Pollution Control Officer shall either approve the certification and include the subject model on the list of certified devices, or deny the certification.
(4) A manufacturer shall submit to the Air Pollution Control Officer a new certification application for any unit model previously certified in accordance with Section (f) Manufacturer Requirements whose design is changed in any manner which may alter oxides of nitrogen or carbon monoxide emissions.
(5) A manufacturer shall maintain laboratory or source test records for oxides of nitrogen, carbon monoxide, and oxygen content emissions, and certification records in electronic and/or hardcopy format for as long as the new unit model is offered for sale or sold within San Diego County, or for three calendar years after date of manufacture, whichever is longer. Such records shall be provided to the District upon request.
Note that for medium boilers certification is NOT authority to operate. You must obtain District authority to install and/or operate your medium boiler. This authority is separate from boiler certification. To obtain authority to operate your medium boiler contact Permits staff. To certify your unit please email the District's Compliance Division.