SJVUAPCD 4902 - 1 6/17/93

RULE 4902 RESIDENTIAL WATER HEATERS (Adopted June 17, 1993)

1.0 Purpose

The purpose of this rule is to limit oxides of nitrogen emissions from residential water

heaters.

2.0 Applicability

This rule applies to residential natural gas-fired water heaters.

3.0 Definitions

3.1 Natural Gas-Fired Water Heater: A closed vessel, in which water is heated by the

combustion of natural gas and is withdrawn for use external to the vessel at

pressures not exceeding 160 psig, including the apparatus by which heat is

generated and all controls and devices necessary to prevent water temperatures

from exceeding 210°F

3.2 Natural Gas: A mixture of gaseous hydrocarbons containing at least 80 percent

methane by volume as determined according to Standard Method ASTM D1945-

64

3.3 Heat Output: The product obtained by multiplying the recovery efficiency, as

defined by Section 6.1.3 of the Code of Federal Regulation, Title 10, Part 430,

Subpart B, Appendix E, by the input rating of the water heater.

3.4 Input Rating: The amount of energy a water heater consumes in one hour

(Btu/Hour).

4.0 Exemptions

4.1 Natural gas-fired water heaters with rated heat input of greater than 75,000 Btu

per hour.

4.2 Water heaters using fuels other than natural gas.

4.3 Natural gas-fired heaters used exclusively to heat swimming pools or hot tubs.

4.4 Water heaters used exclusively in recreational vehicles.
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5.0 Requirements

5.1 Natural Gas-Fired Water Heaters with a rated heat input less than or equal to

75,000 Btu/hr: No person shall sell, install or offer for sale within the District any

natural gas-fired water heater manufactured after December 17, 1993 that emits

more than 40 nanograms of nitrogen oxides (calculated as NO2) per Joule of heat

output.

5.2 Certification of Water Heaters: Water heaters subject to section 4.1 of this rule

shall be certified in accordance with sections 5.1, 5.2 and 5.3.

6.0 Administrative Requirements

6.1 Each tested water heater shall be operated in accordance with Section 2.4 of

American National Standards ANSI Z21.10.1-1990 at normal test pressure, input

rates, and with a five-foot exhaust stack installed during the nitrogen oxides

emission tests.

6.2 Certification: The manufacturer shall demonstrate that each water heater model

subject to the requirements of section 4.1 has been tested in accordance with EPA

Reference Test Method 7E, 40 CFR Part 60, Appendix A.

6.2.1 The following formula shall be used to calculate the emissions of NOx in

nanograms of NOx per Joule of heat output:

N = (4.566 x 104 x P x U)/(H x C x E)

Where:

N = NOX emission rate in nanograms of NOX emitted

per Joule of heat output

4.566 x 104

 = unit conversion factor (ppm to nanograms and Btu

to Joules)

P = Concentration of NOX in the flue gas in parts per

million (volume)

U = Dry volume percent of CO2 in flue gas necessary

for stoichiometric combustion

H = Gross heating value of the gas, Btu/Cu ft (at 60°F

and 30" Hg)

C = Dry volume percent of CO2 in flue gas

E = Recovery efficiency, percentage, as defined in

Section 6.1.3 of the Code of Federal Regulation,

Title 10, Part 430, Subpart B, Appendix E
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6.2.2 The manufacturer may submit to the APCO an approved SCAQMD,

Ventura County or BAAQMD certification in lieu of conducting

duplicative certification tests.

6.3 Compliance Statement: Upon request of the APCO, each manufacturer shall

submit to the APCO a statement certifying the water heaters subject to this rule

are in compliance with the provisions of section 5.1. The statement shall be

signed, dated and shall attest to the accuracy of all information. The statement

shall include:

General Information:

Name and address of manufacturer,

Brand name,

Model number, as it appears on the water heater rating plate,

Heat input rating, Btu/hr.

6.4 Identification: The manufacturer shall display the model number of the water

heater and date of manufacture on the shipping carton and rating plate of each

unit.
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