YOLO-SOLANO AIR QUALITY MANAGEMENT DISTRICT

RULE 2.37 - NATURAL GAS-FIRED RESIDENTIAL WATER HEATERS
(Adopted November 9, 1994)

INDEX

100 GENERAL

101 PURPOSE

102 APPLICABILITY

110 EXEMPTIONS


200 DEFINITIONS

201 BRITISH THERMAL UNIT (BTU)

202 HEAT INPUT

203 HEAT OUTPUT

204 NATURAL GAS

205 RATED HEAT INPUT CAPACITY

206 WATER HEATER

300 STANDARDS

301 PROHIBITIONS

400 ADMINISTRATIVE REQUIREMENTS

401 COMPLIANCE REPORT

402 LABELING

500 MONITORING AND RECORDS

501 TEST METHODS

502 RECORDS




100 GENERAL

101 PURPOSE: The purpose of this Rule is to limit the emissions of oxides of nitrogen (NOx) from the use of natural gas-fired residential hot water heaters.

102 APPLICABILITY: The provisions of this Rule shall apply to any person that manufactures, offers for sale, sells, or installs any natural gas-fired water heater with a rated heat input capacity of less than 75,000 British Thermal Units per hour (BTU/hr).

110 EXEMPTIONS: The provisions of this Rule shall not apply to:

110.1 Water heaters with a rated heat input of 75,000 BTU/hr or greater.

110.2 Water heaters used in recreational vehicles.

110.3 Water heaters used exclusively to heat swimming pools and hot tubs.

200 DEFINITIONS

201 BRITISH THERMAL UNIT (BTU): The amount of heat required to raise the temperature of one pound of water from 59o F to 60o F at one atmosphere.

202 HEAT INPUT: The actual amount of heat released by natural gas burned in the water heater.

203 HEAT OUTPUT: The product obtained by multiplying the recovery efficiency, as defined by Title 20, California Administrative Code, Chapter 2, Subchapter 4, Sections 1603 and 1607, by the heating value of the natural gas furnished to the water heater.

204 NATURAL GAS: A mixture of gaseous hydrocarbons containing at least 80 percent methane by volume as determined according to ASTM Test Method D1945-64.

205 RATED HEAT INPUT CAPACITY: The heat input capacity specified on the nameplate of the combustion unit. If the combustion unit has been altered or modified such that its maximum heat input is different than the heat input capacity specified on the nameplate, the new maximum heat input shall be considered as the rated heat input capacity.

206 WATER HEATER: A device that heats water at a thermostatically-control temperature for delivery on demand.


300 STANDARDS

301 PROHIBITIONS: Effective May 31, 1995, no person shall manufacture, offer for sale, sell, or install any natural gas-fired water heater with oxides of nitrogen (NOx) emissions in excess of 40 nanograms calculated as weight equivalent NO2 per joule (ng/j) [93 pounds per Billion BTU] (93 lb/109 BTU) of heat output.


400 ADMINISTRATIVE REQUIREMENTS

401 COMPLIANCE REPORT: A manufacturer shall submit to the Air Pollution Control Officer a Compliance Report that demonstrates compliance with Section 301 of this Rule for each water heater model subject to the provisions of this Rule. A manufacturer shall submit a new compliance report for any water heater model whose design is changed in any manner which may alter NOx emissions. These Compliance Reports, for either new or altered models, shall be submitted to the District at least 30 days before the water heater model is offered for sale,sold, or installed within the District. The compliance Report shall contain all the following information:

401.1 General Information:

  1. Name and address of manufacturer;
  2. Brand name and model;
  3. Model number as it appears on the rating plate of each water heater;
  4. Description of each water heater model being certified; and
  5. Heat input rating.

401.2 Test Report:

  1. All compliance test procedures and results for each water heater model; and
  2. All calculations for determining compliance of each water heater model.
  3. The manufacturer may submit to the District an approved Bay Area AQMD or South Coast AQMD certification in lieu of conducting duplicative compliance tests.

401.3 Compliance Statement: A signed and dated statement attesting to the accuracy of all statements and information in the Compliance Report.

402 LABELING: The manufacturer shall display the model number of the water heater complying with the requirements specified in Section 301 of this Rule on the water heater shipping carton and rating plate.


500 MONITORING AND RECORDS

501 TEST METHODS: The manufacturer shall have each water heater model tested in accordance with the following:

501.1 Each tested water heater shall be operated in accordance with Section 2.4 of American National Standard ANSI Z21.10.1-1975 at normal test pressure, input rates, and with a five-foot exhaust stack installed during NOx emissions tests.

501.2 The measurement of NOx emissions shall be conducted in accordance with the EPA Reference Test Method 7E (40 CFR 60, Appendix A). The determination of CO2 shall be conducted in accordance with EPA Reference Test Method 3A (40 CFR 60, Appendix A). Other methods require approval by the Air Pollution Control Officer and the U.S. EPA.

501.3 The following procedure shall be used to calculate the NOx emissions rate in ng/j (lb/BTU)of heat output:

N

=

5211 x Cf x P x F

   

Hc x C

where:

N = Nanograms of NOx expressed as weight equivalent NO2 per joule of heat output, ng/j (lb/109 BTU).

Cf = Carbon number of fuel, dimensionless.

P = NOx concentration in flue gas, ppmv.

F = Volume of fuel burned, cubic feet at 30 inches of Hg and 60o F.

Hc = Heat output, BTU.

C = Concentration of CO2 measured in flue gas, percent.

The definitions of and the measurement procedure for the above listed parameters are described in South Coast AQMD's Rule 1121 Nitrogen Oxides Emissions Compliance Testing for Natural Gas-Fired Water Heaters and Small Boilers.

501.4 A manufacturer that has certified a water heater model to demonstrate compliance with a State or local agency rule that meets the requirements of this Rule may submit the test results to the District in lieu of conducting duplicative testing.

502 RECORDS: A manufacturer shall keep Compliance Reports, test reports, and compliance statements for as long as the water heater model is offered for sale, sold, or installed within the District, or for two years, whichever is longer.