GOVERNING BOARD

Skip Barwick, Chair

Councilmember, City of Tulare 

Hub Walsh, Vice Chair

Supervisor, Merced County

Oliver L. Baines III

Councilmember, City of Fresno

Tony Barba

Supervisor, Kings County

Sally J. Bomprezzi

Councilmember, City of Madera

Dennis Brazil

Mayor, City of Gustine

Judith G. Case

Supervisor, Fresno County 

David Couch

Supervisor, Kern County

Bob Elliott

Supervisor, San Joaquin County

Harold Hanson

Councilmember, City of Bakersfield

William O’Brien

Supervisor, Stanislaus County

Alexander C. Sherriffs, M.D.

Appointed by Governor

Tom Wheeler

Supervisor, Madera County

J. Steven Worthley

Supervisor, Tulare County

Seyed Sadredin

Executive Director

Air Pollution Control Officer

Northern Region Office

4800 Enterprise Way 

Modesto, CA 95356-8718

(209) 557-6400 • FAX (209) 557-6475

Central Region Office

1990 East Gettysburg Avenue

Fresno, CA 93726-0244

(559) 230-6000 • FAX (559) 230-6061

Southern Region Office

34946 Flyover Court

Bakersfield, CA 93308-9725

(661) 392-5500 • FAX (661) 392-5585

www.valleyair.org

DATE: November 14, 2013

TO: SJVUAPCD Governing Board

FROM: Seyed Sadredin, Executive Director/APCO

Project Coordinator: Jessi Fierro/Errol Villegas

RE: ITEM NUMBER 8: ADOPT PROPOSED 

AMENDMENTS TO RULE 4308 (BOILERS, STEAM 

GENERATORS, AND PROCESS HEATERS—0.075 

MMBTU/HR TO LESS THAN 2.0 MMBTU/HR)

RECOMMENDATIONS:

1. Adopt Proposed Amendments to Rule 4308 (Boilers, Steam 

Generators, and Process Heaters—0.075 MMBtu/hr to less than 

2.0 MMBtu/hr).

2. Authorize the Chair to sign the attached Resolution.

BACKGROUND:

Rule 4308 reduces oxides of nitrogen (NOx) emissions from boilers, 

steam generators, and process heaters with a rated heat input capacity 

of 0.075 to less than 2.0 million British thermal units per hour 

(MMBtu/hr) through point-of-sale requirements. In the District’s 2012 

PM2.5 Plan, the District identified an opportunity to further reduce 

emissions from this category by lowering the emission limit for natural 

gas-fired instantaneous water heaters (also known as tankless water 

heaters) with a rated heat input of 0.075 - 0.4 MMBtu/hr. Proposed 

rule amendments would lower the NOx emission limit for instantaneous 

units from 55 parts per million by volume (ppmv) to 20 ppmv, effective 

on and after January 1, 2015. The 2015 effective date would provide 

retailers with sufficient time to sell their remaining 55 ppmv compliant 

units. This proposed amendment would satisfy the commitment 

included in the 2012 PM2.5 Plan to make the amendments by 2013.

In addition to amending the NOx emission limit for instantaneous units, 

the District is proposing several administrative amendments to Rule 

4308 to clarify rule applicability and to remove outdated and redundant 

language. 
SJVUAPCD Governing Board

ITEM NUMBER 8: ADOPT PROPOSED AMENDMENTS TO RULE 4308 (BOILERS, STEAM 

GENERATORS, AND PROCESS HEATERS—0.075 MMBTU/HR TO LESS THAN 2.0 MMBTU/HR)

November 14, 2013

2

DISCUSSION: 

Rule 4308 was last amended on December 17, 2009 to incorporate a 20 ppmv NOx 

emission limit for most categories of natural gas-fired water heaters, with the exception 

of instantaneous water heaters and pool heaters with a rated heat input of 0.075-0.4 

MMBtu/hr. At that time, 20 ppmv compliant instantaneous water heaters and pool 

heaters of this size range were not yet feasible. While pool heater technology is still 

only able to meet a NOx emission limit of 55 ppmv, 20 ppmv compliant instantaneous 

units are now readily available in the 0.075-0.4 MMBtu/hr size range.

The following is a summary of the proposed amendments to Rule 4308 and the results 

of the analyses supporting the proposed amendments.

Summary of Proposed Amendments to Rule 4308

The District is proposing to lower the NOx emission limit for instantaneous units from 55 

ppmv to 20 ppmv. South Coast Air Quality Management District (SCAQMD) Rule 

1146.2, Bay Area Air Quality Management District (BAAQMD) Regulation 9 Rule 6, and 

Ventura County Air Pollution Control District (VCAPCD) Rule 74.11.1 currently have a 

20 ppmv NOx emission limit for instantaneous units. The lower limit was implemented 

in SCAQMD in 2012, BAAQMD in 2013, and will be implemented in VCAPCD in 2014. 

Five of the six instantaneous water heater manufacturers identified produce 55 ppmv 

and 20 ppmv compliant instantaneous units, while one of the manufacturers has 

stopped producing the 55 ppmv compliant units and only produces 20 ppmv compliant 

units due to the rules in place in other California air districts. All six instantaneous water 

heater manufacturers confirmed to the District that they sell 20 ppmv compliant 

instantaneous units to Valley wholesalers or water heater suppliers. In order to allow 

sufficient time to sell any remaining 55 ppmv compliant instantaneous units in stock, the 

55 ppmv NOx emission limit would remain in effect until December 31, 2014 and on and 

after January 1, 2015, instantaneous units sold, installed, or supplied in the Valley 

would be required to meet a 20 ppmv NOx emission limit.

The District is also proposing some administrative amendments to clarify Rule 4308. An 

exemption for hot water pressure washers would be added to clarify that these units are 

not applicable to Rule 4308. Language would be added to Section 6.2.3 to clarify that 

the SCAQMD protocol, “Nitrogen Oxides Emissions Compliance Testing for Natural 

Gas-Fired Water Heaters and Small Boilers,” is only applicable to natural gas-fired 

units. A few definitions would also be added and redundant and expired language 

would be removed from the rule.

Emission Reduction Analysis 

As presented in the 2012 PM2.5 Plan, the annual NOx emissions from this source 

category subject to Rule 4308 were 259 tons per year (tpy) (0.71 tons per day) in 2012. 

Proposed rule amendments would affect a small portion of the total Rule 4308 source 
SJVUAPCD Governing Board

ITEM NUMBER 8: ADOPT PROPOSED AMENDMENTS TO RULE 4308 (BOILERS, STEAM 

GENERATORS, AND PROCESS HEATERS—0.075 MMBTU/HR TO LESS THAN 2.0 MMBTU/HR)

November 14, 2013

3

category, as the baseline NOx emissions from instantaneous units are 2.92 tpy. The 

District did not specify an emission reduction commitment for this proposed rule 

amendment in the 2012 PM2.5 Plan in lieu of conducting a more thorough emission 

reduction analysis in this rule amendment project. 

Instantaneous units have an estimated lifetime of 20 years. Since Rule 4308 is a pointof-sale rule, emission reductions would occur over 20 years, from 2015 through 2034, 

as existing instantaneous units are replaced with newer instantaneous units, new 

instantaneous units are purchased for new developments, and some end-users switch 

from tank-style to instantaneous units. Proposed rule amendments would result in 

approximately 1.82 tpy of NOx emission reductions upon full rule implementation in 

2034, reflecting a 62.3% reduction from baseline emissions. The complete Emission 

Reduction Analysis is presented in Appendix B of the Final Draft Staff Report.

Cost Effectiveness Analysis 

Pursuant to California Health and Safety Code (CH&SC) Section 40920.6(a), the District 

is required to analyze the cost effectiveness of new rules, rule amendments, or planning 

requirements to incorporate all feasible measures. The District has prepared a cost 

effectiveness analysis to analyze the economic feasibility of the proposed rule 

amendments. The estimated cost effectiveness of implementing a 20 ppmv NOx 

emission limit for instantaneous units is approximately $19,961-$52,746 per ton of NOx 

emission reductions. The cost effectiveness analysis is attached as Appendix C of the 

Final Draft Staff Report. 

Socioeconomic Impact Analysis 

Pursuant to CH&SC Section 40728.5, the District is required to analyze the 

socioeconomic impacts of any proposed rule amendments that significantly affect air 

quality or that strengthen an emission limitation. No significant socioeconomic impacts 

are expected from these proposed rule amendments. The socioeconomic analysis is 

attached as Appendix D of the Final Draft Staff Report.

Rule Consistency Analysis 

Pursuant to CH&SC Section 40727.2, the District prepared a rule consistency analysis 

that compares the elements of the proposed amendments for Rule 4308 with the 

corresponding elements of other District rules and federal regulations and guidelines 

that apply to the same type of equipment or source category. Proposed amendments 

would not conflict with other District rules, or federal rules, regulations, or policies 

covering similar stationary sources. The rule consistency analysis is presented in 

Appendix E of the Final Draft Staff Report.
SJVUAPCD Governing Board

ITEM NUMBER 8: ADOPT PROPOSED AMENDMENTS TO RULE 4308 (BOILERS, STEAM 

GENERATORS, AND PROCESS HEATERS—0.075 MMBTU/HR TO LESS THAN 2.0 MMBTU/HR)

November 14, 2013

4

Environmental Impacts

Pursuant to the California Environmental Quality Act (CEQA), the District has 

investigated the possible environmental impacts of the proposed amendments to Rule 

4308. Based on the lack of evidence to the contrary, the District has concluded that the 

proposed amendments to the rule will not have any significant adverse effects on the 

environment. Staff recommends filing a Notice of Exemption under the provisions of the 

CEQA Guidelines 15061 (b)(3).

Rule Development Process

Public Workshop for Rule 4308

The District hosted a public workshop to present, discuss, and hear comments on the 

draft rule and draft staff report on August 22, 2013. The draft rule and staff report were 

made available on the District’s website prior to the public workshop, and a two week 

comment period followed the public workshop. All comments received on or before 

September 9, 2013 were considered and incorporated into Proposed Rule 4308 and the 

Final Draft Staff Report, as appropriate. Comments received and District responses to

the comments are summarized in Appendix A of the Final Draft Staff Report. 

Public Hearing for Rule 4308

In accordance with CH&SC Section 40725, the Proposed Amendments to Rule 4308 

and Final Draft Staff Report were publicly noticed prior to the Governing Board public 

hearing to consider adoption of the proposed amendments to Rule 4308. The proposed

amendments to Rule 4308, Final Draft Staff Report, and other supporting documents

were made available for public comment on October 15, 2013. No comments were 

received during the subsequent two-week comment period. The public is also invited to 

provide comments during the public hearing for proposed adoption of this rule. 

FISCAL IMPACT:

The District expects no fiscal impact to result from this action. 

Attachments:

Attachment A: Resolution for Proposed Amendments to Rule 4308 (4 pages)

Attachment B: Proposed Amendments to Rule 4308 (6 pages)

Attachment C: Final Draft Staff Report with Appendices for Proposed Amendments to Rule 

4308 (50 pages)