CALIFORNIA AIR RESOURCES BOARD

SIP COMPLETENESS CHECKLIST

(Electronic Format)

*** TO BE COMPLETED BY DISTRICT AND RETURNED TO ARB ***

All rules submitted to the EPA as State Implementation Plan (SIP) revisions must be supported by certain information and

documentation for the rule packages to be deemed complete for review by the EPA. Rules will not be evaluated for

approvability by the EPA unless the submittal packages are complete. To assist you in determining that all necessary

materials are included in rules packages sent to the ARB for submittal to the EPA, please fill out the following form and

include it with the rule package you send ARB. See the ARB's Guidelines on the Implementation of the 40 CFR 51,

Appendix V, for a more detailed explanation than is provided here. Adopted rules and rule amendments should be checked

against U.S. EPA's Guidance Document for Correcting Common VOC & Other Rule Deficiencies (Little Blue Book, August

21, 2001) to ensure that they contain no elements which will result in disapproval by EPA.

District: Yolo-Solano AQMD Rule No: 2.37 Date Adopted or Amended: April 8, 2009

Rule Title: Natural Gas-Fired Water Heaters and Small Boilers

ADMINISTRATIVE MATERIALS

Note: All documents should be in electronic format. Items that have signatures, initials, or stamps may be scanned.

Not

Attached Attached N/A

(X) ( ) ( ) COMPLETE COPY OF THE RULE: Provide an unmarked copy of the entire

rule as adopted or amended by your District Board.

(X) ( ) () UNDERLINE AND STRIKEOUT COPY OF THE RULE: If an amended rule,

provide a complete copy of the rule indicating in underline and strikeout

format all language which has been added, deleted, or changed since the rule

was last adopted or amended.

( ) ( ) (X) COMPLETE COPY OF THE REFERENCED RULE(S): For any rule which

includes language specifically referencing another rule, a copy of that other

rule must also be submitted, unless it has already been submitted to EPA as

part of a previous SIP submittal.

(X) ( ) ( ) PUBLIC NOTICE EVIDENCE: Include a copy of the local newspaper clipping

certification(s), stating the date of publication, which must be at least 30 days

before the hearing. As an alternative, include a copy of the actual published

notice of the public hearing as it appeared in the local newspaper(s). In this

case, however, enough of the newspaper page must be included to show the

date of publication. The notice must specifically identify by title and number

each rule adopted or amended.

(X) ( ) ( ) RESOLUTION/MINUTE ORDER: Provide the Board Clerk certified resolution

or minute order. This document must include certification that the hearing

was held in accordance with the information in the public notice. It must also

list the rules that were adopted or amended, the date of the public hearing,

and a statement of compliance with California Health and Safety Code

Sections 40725-40728 (Administrative Procedures Act).

(X) ( ) ( ) PUBLIC COMMENTS AND RESPONSES: Submit copies of written public 

 comments made during the notice period and at the public hearing. Also 

submit any written responses prepared by the District staff or presented to 

the District Board at the public hearing. A summary of the public 

comments and responses is adequate. If there were no comments made 

during the notice period or at the hearing, please indicate N/A to the left.
CALIFORNIA AIR RESOURCES BOARD

SIP COMPLETENESS CHECKLIST

(Electronic Format)

TECHNICAL MATERIALS

Not

Attached Attached N/A

(X) ( ) ( ) RULE EVALUATION FORM: See instructions for completing the Rule

Evaluation Form and the accompanying sample form.

( ) ( ) (X) NON-EPA TEST METHODS: Attach all test methods that are referenced in

your rule that do not appear in 40 CFR 51, 60, 61, 63, or have not been

previously submitted to EPA. EPA methods used in other media such as

SW846 for solid waste are not automatically approved for air pollution

applications. Submittal of test methods that are not EPA-approved should

include the information and follow the procedure described in Region 9’s “Test

Method Review & Evaluation Process.”

( ) ( ) (X) MODELING SUPPORT: Provide if appropriate. In general, modeling support

is not required for VOC and NOx rules to determine their impacts on ozone

levels. Modeling is required where a rule is a relaxation that affects large

sources (> 100 TPY) in an attainment area for SO2, directly emitted PM10,

CO, or NOx (for NO2 purposes). In cases where EPA is concerned with the

impact on air quality of rule revisions which relax limits or cause a shift in

emission patterns in a nonattainment area, a reference back to the approved

SIP will be sufficient provided the approved SIP accounts for the relaxation

and provided the approved SIP used the current EPA modeling guidelines.

If current EPA modeling guidelines were not used, then new modeling may be

required.

( ) ( ) (X) ECONOMIC AND TECHNICAL JUSTIFICATION FOR DEVIATIONS FROM

EPA POLICIES: The District staff report or other information included with the

submittal should discuss all potential relaxations or deviations from RACT,

RACM, BACT, BACM, enforceability, attainment, RFP, or other relevant EPA

requirements. This includes, for example, demonstrating that exemptions or

emission limits less stringent than the presumptive RACT (e.g., a CTG) meet

EPA’s 5 percent policy, and demonstrating that all source categories

exempted from a RACM/BACM rule are de minimus according to EPA’s

RACM/BACM policy.

(X) ( ) ( ) ADDITIONAL MATERIALS: Provide District staff reports and any other

supporting information concerning development of the rule or rule

changes. This information should explain the basis for all limits and

thresholds contained in the rule.
CALIFORNIA AIR RESOURCES BOARD

APCD/AQMD RULE EVALUATION FORM – Page 1

(Electronic Format)

I. GENERAL INFORMATION

District: Yolo-Solano Air Quality Management District

Rule No(s): 2.37 Date Adopted/Amended/Rescinded: Amended April 8, 2009

Title: Natural Gas-Fired W ater Heaters and Small Boilers

Date Submitted to ARB: April 28, 2009 

If Amended Rule(s), Date Last Amended or Adopted: Adopted November 9, 1994 

Is the Rule Intended to be sent to U.S. EPA as a SIP Revision? Yes (X) No ( ) (If No, do not complete remainder of

form)

District Contact: Matt Jones Phone Number: (530) 757-3668 e-mail Address: mjones@ysaqmd.org

Narrative Summary of New Rule or Rule Changes: New Rule () Amended Rule (X) 

The amended Rule 2.37 expanded the scope of water heater units applicable under the rule by regulating units with rated heat

input capacities up to 1,000,000 British thermal units per hour (Btu/hr). Water heater units were categorized by their rated heat

input capacity and NOx emission limits for each of the categories were established. Amendments also included a revision to

the exemption for pool/spa heaters by regulating units with rated heat input capacities greater than 400,000Btu/hr but less

than1,000,000 Btu/hr.

Pollutant(s) Regulated by the Rule (Check): ROG ( ) NOx (X) SO2 ( )

CO ( ) PM (X) TAC ( ) (name): 

I. EFFECT ON EMISSIONS

Complete this section ONLY for rules that, when implemented, will result in quantifiable changes in emissions. Attach

reference(s) for emission factor(s) and other information. Attach calculation sheet showing how the emission information

provided below was determined.

Net Effect on Emissions: Increase ( ) Decrease (X) N/A ( )

Emission Reduction Commitment in SIP for this Source Category: 1.3912 tpd NOx

Inventory Year Used to Calculate Changes in Emissions: 2006 Area Affected: SFNA

Future Year Control Profile Estimate (Provide information on as many years as possible): Based on Health Department

list of restaurants in the District's eight county area, there are approximately 150 restaurants that are impacted by the

adoption of Rule 4692. The overall percent reduction from source specific baseline per year is approximately 83 percent.
CALIFORNIA AIR RESOURCES BOARD

APCD/AQMD RULE EVALUATION FORM - Page 2

(Electronic Format)

Baseline Inventory in the SIP for the Control Measure: 1.2918 tpd NOx

Emissions Reduction Commitment in the SIP for the Control Measure: 0.2403 tpd NOx as of 2018

Revised Baseline Inventory (if any): N/A

Revised Emission Reduction Estimate (if developed): N/A

Note that the district’s input to the Rule Evaluation Form will not be used as input to the ARB’s emission forecasting and

planning.

III. SOURCES/ATTAINMENT STATUS

District is: Attainment ( ) Nonattainment (X) Split ( )

Approximate Total Number of Small (<100 TPY) Sources Affected by this Amendment: This rule amendment will be

applied at the point of sale which restricts manufacturers, distributors, retailers, and contractors from selling or installing

non-compliant units for use in our District. There are approximately 59,504 residences in the District that use natural gas

for water heating that would be applicable to the rule. The number of commercial units subject to the rule is unknown

since this source is currently unregulated. The emissions attributed to the source are acounted for in the area source

inventory.

Percent in Nonattainment Area: 100%

Number of Large (> 100 TPY) Sources Controlled: None Percent in Nonattainment Area: N/A%

Name(s) and Location(s) (city and county) of Large (> 100 TPY) Sources Controlled by Rule (Attach additional sheets as

necessary): N/A

IV. EMISSION REDUCTION TECHNOLOGY

Does the Rule Include Emission Limits that are Continuous? Yes (X) No ( )

If Yes, Those Limits are in Section(s) 301 of the Rule.

Other Methods in the Rule for Achieving Emission Reductions are: N/A

V. OTHER REQUIREMENTS

The Rule Contains:

Emission Limits in Section(s): 301 W ork Practice Standards in Section(s): N/A

Recordkeeping Requirements in Section(s): 400 & 500 Reporting Requirements in Section(s): 400 & 500
CALIFORNIA AIR RESOURCES BOARD

APCD/AQMD RULE EVALUATION FORM - Page 3

(Electronic Format)

VI. IMPACT ON AIR QUALITY PLAN

No Impact ( ) Impacts RFP ( ) Impacts attainment (X)

Discussion: The new rule is expected to result in emission reductions of 0.4976 tpd of NOx by 2018. Reductions in NOx and

secondary PM will help the Basin achieve state and federal RFP requirements and further progress toward attainment of ozone

and PM2.5 standards.



Yolo-Solano AQMD

Adopted November 9, 1994

Revised April 8, 2009 Reg. II, Rule 2.37, Page 1

RULE 2.37

NATURAL GAS-FIRED WATER HEATERS AND SMALL BOILERS

ADOPTED November 9, 1994

REVISED April 8, 2009

INDEX

100 GENERAL

101 PURPOSE

102 APPLICABILITY

103 SEVERABILITY

110 EXEMPTIONS

200 DEFINITIONS

201 BRITISH THERMAL UNIT (BTU)

202 HEAT INPUT

203 HEAT OUTPUT

204 LARGE WATER HEATER

205 MOBILE HOME WATER HEATER 

206 NATURAL GAS

207 POOL / SPA HEATER

208 RATED HEAT INPUT CAPACITY

209 SMALL BOILER

210 SMALL WATER HEATER

211 TANKLESS WATER HEATER

212 WATER HEATER

300 STANDARDS

301 PROHIBITIONS

400 ADMINISTRATIVE REQUIREMENTS

401 COMPLIANCE REPORT

402 LABELING

500 MONITORING AND RECORDS

501 TEST METHODS

502 RECORDS
Yolo-Solano AQMD

Adopted November 9, 1994

Revised April 8, 2009 Reg. II, Rule 2.37, Page 2

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 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 less than 1,000,000 British Thermal Units per hour

(Btu/hr).

103 SEVERABILITY: If any provision, clause, sentence, paragraph, section or part of

this rule for any reason is judged to be unconstitutional or invalid, such judgement

shall not affect or invalidate the remainder of the rule.

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

110.1 Water heaters with a rated heat input of 1,000,000 Btu/hr or greater.

110.2 Water heaters used in recreational vehicles.

110.3 Water heaters used to heat pools/spas with a rated heat input capacity less

than or equal to 400,000 Btu/hr.

200 DEFINITIONS

201 BRITISH THERMAL UNIT (BTU): The amount of heat required to raise the

temperature of one pound of water from 59E F to 60E 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 10, of the Code of Federal Regulation, Section 6.1.3, Part 430,

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

204 LARGE WATER HEATER: A natural gas-fired water heater with a rated heat

input capacity ranging from 75,000 - 400,000 Btu/hour.

205 MOBILE HOME WATER HEATER: A natural gas-fired water heater

manufactured exclusively for use in a mobile home.

206 NATURAL GAS: A mixture of gaseous hydrocarbons containing at least 80 percent

methane by volume as determined according to ASTM Test Method D1945-03.

207 POOL / SPA HEATER: A device through which water is heated when pool or spa

water circulates through a heat exchanger.

208 RATED HEAT INPUT CAPACITY: The heat input capacity specified on the

nameplate of the combustion unit. If the combustion unit has been physically altered

or modified such that its maximum heat input is different than the heat input capacity
Yolo-Solano AQMD

Adopted November 9, 1994

Revised April 8, 2009 Reg. II, Rule 2.37, Page 3

specified on the nameplate, the new maximum heat input shall be considered as the

rated heat input capacity.

209 SMALL BOILER: A natural gas-fired water heater with a rated heat input capacity

greater than 400,000 but less than 1,000,000 Btu/hour (1 MM Btu/hr).

210 SMALL WATER HEATER: A natural gas-fired water heater with a rated heat

input capacity less than 75,000 BTU/hour.

211 TANKLESS WATER HEATER: A water heating device that does not use a

storage tank to hold heated water. An electric ignition source is used to initiate water

heating and then natural gas is introduced to fuel further combustion using multiple

modulating burners to heat water on demand.

212 WATER HEATER: A device that heats water at a thermostatically-controlled

temperature including storage tank and tankless units.

300 STANDARDS

301 PROHIBITIONS: 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

the limits set forth in the compliance schedule indicated below: 

Category Rated Heat

Input Capacity

(Btu/hour)

NOx Emission

Limit

Effective

5/31/1995 -

12/31/2009

NOx Emission

Limit 

Effective

1/1/2010 -

12/31/2013

NOx Emission

Limit 

Effective

1/1/2014

Small water

heater < 75,000 40ng/J

10ng/J or

15 ppm NOx 

@ 2 3% O dry

10ng/J or

15 ppm NOx 

@ 2 3% O dry

Large water

heater 75,000 -

400,000

No present

standard

40ng/J or 

55 ppm NOx 

@ 2 3% O dry

14ng/J or

20 ppm NOx 

@ 2 3% O dry

Small boiler > 400,000 -

 < 1,000,000

No present

standard

20ng/J or

30 ppm NOx 

@ 2 3% O dry

14ng/J or

20 ppm NOx 

@ 2 3% O dry

Mobile

home water

heater

All No present

standard

40ng/J or

55 ppm NOx 

@ 2 3% O dry

40ng/J or

55 ppm NOx 

@ 2 3% O dry

Pool/spa

heater > 400,000 -

 < 1,000,000

No present

standard

40ng/J or

55 ppm NOx 

@ 2 3% O dry

14ng/J or

20 ppm NOx 

@ 2 3% O dry
Yolo-Solano AQMD

Adopted November 9, 1994

Revised April 8, 2009 Reg. II, Rule 2.37, Page 4

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 anymanner 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:

a. Name and address of manufacturer;

b. Brand name and model;

c. Model number as it appears on the rating plate of each water heater;

d. Description of each water heater model being certified; and

e. Heat input rating.

401.2 Test Report:

a. All compliance test procedures and results for each water heater

model; and

b. All calculations for determining compliance of each water heater

model.

c. The manufacturer may submit to the District an approved Bay Area

AQMD Regulation 9 Rule 6 or South Coast AQMD Rule 1121 or

1146.2 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

the American National Standards Institute ANSI Z21.10.1,1990 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.
Yolo-Solano AQMD

Adopted November 9, 1994

Revised April 8, 2009 Reg. II, Rule 2.37, Page 5

501.3 The following procedure shall be used to calculate the NOx emissions rate in

ng/J (lb/BTU) of heat output:

N = 4.566 x 10 x P x U 4

 H x C x E

where:

N = NOx emission rate in nanograms of NOx emitted per

joule of heat output. 

=

4.566 x 10 unit conversion factor (ppm to nanograms and Btu to

4

joules)

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

million (volume)

U = Dry 2 volume percent of CO in flue gas necessary for

stoichiometric combustion

H = Gross heating value of the gas, Btu/ft (at 60EF and 30 3

in Hg)

C = Dry 2 volume percent of CO 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.

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 five years, whichever is longer.