DAQ-2024-008502

June 14, 2024

Ryan Bares
Erica Pryor
Utah Department of Environmental Quality (DEQ)
Division of Air Quality
PO Box 144820
Salt Lake City, UT 84114-4820

RE: AHRI Comments to Utah DEQ on the proposed amendments to rules R307-315 and
R307-316: NOx Emissions Controls for Natural Gas-Fired Boilers

Sent via email to: [e-mail] and [e-mail]

Dear Mr. Bares and Ms. Pryor:

The Air-Conditioning, Heating, and Refrigeration Institute (AHRI) welcomes the opportunity to
comment on the Utah Department of Environmental Quality (DEQ) proposed amendments to rules
R307-315: NOx Emissions Controls for Natural Gas-Fired Boilers 2.0-5.0 MMBtu and R307-316:
NOx Emissions Controls for Natural Gas-Fired Boilers greater than 5.0 MMBtu (Proposed Rules).

AHRI represents more than 330 manufacturers of heating, ventilation, air conditioning, commercial
refrigeration (HVACR) and water heating equipment. It is an internationally recognized advocate for
the HVACR and water heating industry and certifies the performance of many of the products
manufactured by its members. In North America, the annual economic activity resulting from the
HVACR industry is more than $211 billion. In the United States alone, AHRI member companies,
along with distributors, contractors, and technicians employ more than 704,000 people.

AHRI is committed to and supports greenhouse gas (GHG) emission reductions, while promoting
sustainable, safe, reliable, and affordable access to the essential air and water heating and cooling
provided by the products they manufacture.

Two fundamental pillars of industry are certainty and consistency. The changes proposed below
address certainty. However, consistency is achieved through alignment on NOx requirements, across
jurisdictions, as proposed in our comments, to provide a clear, consistent path forward for
manufacturers. The scope of the proposal needs to be not only feasible to meet and enforce but also
unambiguous and consistent for all manufacturers. Finally, there needs to be an appropriate time
period for manufacturers to certify and list their products to the rules’ requirements to ensure
consumers can obtain affordable and timely replacements of their boilers.

AHRI Comments – Utah DEQ on the proposed amendments to rules R307-315 and R307-316: NOx
Emissions Controls for Natural Gas-Fired Boiler
June 14, 2024

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1. General Comments on Both Rules

a) Scope of the rule.

AHRI requests that Utah DEQ modify the scope of both rules to only apply NOx
requirements to new and replacement boilers. The requirement to meet the proposed NOx
requirements when replacing a burner or modifying a boiler is infeasible, especially
considering the ability to meet safety certification requirements. While the burner plays a role
in the production of NOx, the whole combustion system works together to meet a nine ppmv
NOx emissions limit. To meet this requirement, the entire boiler system would need to be
replaced by the owner/consumer. Additionally, modifications to a boiler to bring it into
compliance, if done incorrectly, could breach the safety certification requirements and/or the
manufacturers’ installation instructions for the boiler. Finally, the scope of the rule is
ambiguous, as written, for 2.0 MMBtu/hr products. Section R307-315 states that the purpose
of the rule is to set a requirement that the “...total rated heat input has to be at least 2.0
MMBtu/hr. and not more than 5.0 MMBtu/hr."1 While section R307-315.2 states that the
applicability of the rule is for products that have “…has a total rated heat input greater than
2.0 MMBtu/hr. and not more than 5.0 MMBtu/hr."2 AHRI notes that the purpose is inclusive
of 2.0 MMBtu/hr. products while the applicability is not. AHRI requests that Utah DEQ align
these two sections. Given the limitations on NOx reduction through burner replacement
outlined above, and the additional cost to consumers if the entire boiler needs to be
replaced upon repair or replacement of a burner, AHRI requests that Utah DEQ
remove burner replacements and boiler modifications from the scope of this rule.

Utah is proposing to meet a CO emission rate of 200 ppmv or less. AHRI requests Utah
DEQ modifies both rules to harmonize with other California Air District Jurisdiction
Rules3 for CO emissions that are currently in effect for boilers with inputs between 2.0
MMBtu/hr. and 5.0 MMBtu/hr. for CO emissions.

b) Exemptions required for successful implementation.

Boilers used in critical applications, at certain facilities (i.e., hospitals), are designed to utilize
N+1 redundancy to ensure continued heating and sterilization in the event of a failure. This
N+1 redundancy requires a backup system to maintain continuous boiler operation. This is
typically accomplished with multiple dual-fuel boilers which run on both natural gas and fuel
oil. The system allows the unit to switch to on-hand fuel oil if there is a disruption in natural

1 Utah DEQ proposed amendment to Section R307-315, NOx Emission Controls for Natural Gas- Fired Boilers 2.0-
5.0 MMBtu.
2 Utah DEQ proposed amendment to Section R307-315.2, Applicability.
3 The following California Air District Rules are currently in effect for boilers with inputs between 2.0 MMBtu/hr
and 5.0 MMBtu/hr, all these rules set a CO emissions limit of 400 ppm:
• Bay Area Air Quality Management District Regulation 9, Rule 7-307.1
• Sacramento Metro Area Air Quality Management District Rule 411
• San Diego County Air Pollution Control District Rule 62.2.2
• San Joaquin Valley Unified Air Pollution Control District Rule 4307
• Santa Barbara Air Pollution Control District Rule 361
• South Coast Air Quality Management District Rule 1146.1
• Ventura County Air Pollution Control District Rule 74.15.1
AHRI Comments – Utah DEQ on the proposed amendments to rules R307-315 and R307-316: NOx
Emissions Controls for Natural Gas-Fired Boiler
June 14, 2024

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gas supply. These dual-fuel burners are typically considered to be low-NOx at a threshold of
30 ppmv. As a result, AHRI requests that exemptions are made to allow for the safe and
continued operation of dual-fuel boilers in critical applications.

c) Cost of implementation not considered.

In many cases, implementation of both rules will require facilities to upgrade from a non-
condensing boiler to a condensing boiler, which will come at a significant cost to the
consumer. When switching from a non-condensing boiler, the unit must be switched from
natural draft venting to induced draft venting. This switch can be problematic if there is
shared venting between a non-condensing appliance and a condensing appliance. In this
situation, a second venting path will need to be implemented and the facility modified to
allow the different venting pathways. Additionally, upgrades to the water piping system are
needed because of the higher input temperature required by the non-condensing boiler and
the lower output temperature of a condensing boiler. Therefore, AHRI requests that Utah
DEQ perform a cost benefit analysis examining the cost to consumers versus the
benefits achieved through the lower NOx emissions and the measuring of CO emissions.

d) Timing of compliance.

The compliance deadline, May 1, 2024, for these proposed rules does not provide sufficient
time for manufacturers to identify and certify compliant products. As outlined in the
following paragraphs, AHRI does not see a clear path forward to meet the emission limits.
Moreover, manufacturers need ample time to review the compliance requirements, make
necessary design changes to meet the requirements, test, and certify their products are
compliant. AHRI requests that Utah DEQ change the compliance date for this rule from
May 1, 2024 to be no less than 18 months after the date of the publication of the final
rule.

e) Analysis methods not reliable.

Under “Definitions,” the Proposed Rules recommend that “combustion analysis” should
mean “an analysis performed on flue gases using a portable instrument which measures a
range of variables…” AHRI recommends that in the above language DEQ insert the
word “calibrated” before “portable instrument” to ensure reliable data is collected.

2. Comments related to R307-315

As noted above, the certification requirements for this rule are unclear. The lack of a robust
set of certification requirements to be used across industry will lead to market confusion and
a lack of consistency across manufacturers. AHRI requests that Utah DEQ accept
products certified to other air quality districts with similar or more stringent NOx
emissions standards, such as the certification program in California for the South Coast
Air Quality Management District (SCAQMD) for compliance to the current version of
1146.1, as compliant with R307-315.

AHRI Comments – Utah DEQ on the proposed amendments to rules R307-315 and R307-316: NOx
Emissions Controls for Natural Gas-Fired Boiler
June 14, 2024

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3. Comments related to R307-316

Similar to AHRI’s comments related to certification to R307-315, a robust set of certification
requirements is paramount to eliminate market confusion and meet emission standards.
Critically, field tests are affected by many variables making them inconsistent when
compared to laboratory testing. Field testing should be kept to a minimum for this rule, and
requirements and procedures must be in place to ensure the tests are reliable and repeatable.
A fully compliant boiler may fail a field test, due to a lack of calibrated equipment or the test
was not conducted in a controlled environment. In all field tests, but especially in areas of
non-attainment, background NOx needs to be accounted for as part of the measurement to
ensure accurate emission readings from the boiler. Further field tests are typically performed
with portable NOx analyzers that have significantly worse accuracy and resolution when
compared with laboratory testing equipment. This increase in uncertainty needs to be
accounted for with a tolerance on the acceptable field test NOx readings. Finally, an accurate
field test NOx reading is difficult to ensure given the less than perfect conditions in the field.
Small variations in air currents during the test can cause the emissions rates to fluctuate
significantly. This inability to maintain ideal combustion conditions will lead to wavering
NOx readings which will be difficult to determine if the cause is the unit under test or the
measurement equipment.

Unlike R307-315, AHRI is currently unaware of a program that certifies the NOx emissions
of boilers greater than 5.0 MMBtu to be less than 9 ppmv. There are programs in place for
testing of these products and emissions, such as the SCAQMD, which sets a specific manual
of procedures for determining the NOx emissions of the product. AHRI requests that Utah
DEQ adopts an existing laboratory test standard for testing NOx emissions of boilers
greater than 5.0 MMBtu, like the provisions put forth in the current version of
SCAQMD 1146.

We appreciate the opportunity to provide these comments. If you have any questions regarding this
submission, please do not hesitate to contact me.

Sincerely,

Nicole Colantonio
Director, Regulatory Affairs
Email: [e-mail]