Rule 1147 Compliance in California: NOx Testing, CO Testing & Source Testing Requirements
Is your combustion equipment ready for South Coast AQMD Rule 1147 compliance?
If your facility operates permitted gas- or liquid-fueled combustion equipment that is not covered by another Regulation XI rule, South Coast AQMD Rule 1147 – NOx Reductions from Miscellaneous Sources may apply to your equipment. The rule is designed to reduce NOx emissions while limiting CO emissions.
For manufacturers, industrial facilities, commercial operations, environmental managers and plant owners, understanding Rule 1147 is important because compliance can involve emission limits, source testing, monitoring, combustion-system maintenance, recordkeeping and permit requirements.
Important: Rule 1147 is a South Coast AQMD rule, not a uniform statewide California requirement.
What Is Rule 1147?
Rule 1147 – NOx Reductions from Miscellaneous Sources applies to manufacturers, distributors, retailers, installers, owners and operators of gaseous- and/or liquid-fueled combustion equipment that requires a South Coast AQMD permit when another Regulation XI rule does not apply.
The current adopted rule was amended May 6, 2022.
Rule 1147 can cover a wide range of equipment, including:
- Ovens
- Dryers
- Heaters
- Furnaces
- Kilns
- Calciners
- Cookers
- Roasters
- Heated tanks
- Thermal oxidizers
- Catalytic oxidizers
- Afterburners
- Vapor incinerators
- Evaporators
- Fryers
- Parts washers
- Autoclaves
- Make-up air heaters
- Certain turbines
- Other miscellaneous combustion equipment
The exact applicability depends on the equipment, permit status, fuel, heat-input rating and whether another South Coast AQMD rule applies.
Why Rule 1147 Matters to California Industries
NOx emissions contribute to ozone and other air-quality problems. Rule 1147 establishes emission requirements intended to reduce NOx from combustion sources while also establishing CO limits for applicable equipment.
For businesses, compliance is not simply about having a permitted burner.
You need to demonstrate that applicable equipment continues to meet the required emission limits under the applicable compliance pathway.
In simple terms:
Combustion Equipment → Emissions → Testing/Monitoring → Documentation → Compliance
2026 Rule 1147 Update: What Businesses Need to Know
The major regulatory change remains the May 6, 2022 amendment, which introduced updated NOx and CO limits, implementation schedules, monitoring/source-testing requirements, revised exemptions and provisions affecting both RECLAIM and non-RECLAIM facilities.
South Coast AQMD’s current official rule book lists Rule 1147 as amended May 6, 2022.
South Coast AQMD also provides a Rule 1147 Guidance Document dated March 7, 2025, which explains applicability, implementation schedules and source-testing requirements.
What does this mean in 2026?
Facilities should not rely on an old compliance checklist.
Your team should verify:
Current Rule + Current Permit + Equipment Age + Rated Heat Input + Previous Test Date + Applicable Compliance Schedule
Which Equipment Can Be Affected?
Rule 1147 has a broad equipment scope.
Examples include:
🔥 Industrial Heating Equipment
- Furnaces
- Heaters
- Ovens
- Dryers
- Kilns
- Calciners
- Roasters
🏭 Process Equipment
- Heated process tanks
- Evaporators
- Parts washers
- Autoclaves
- Cookers
🌡️ Air & Pollution-Control Equipment
- Make-up air heaters
- Thermal oxidizers
- Catalytic oxidizers
- Afterburners
- Vapor incinerators
⚡ Other Combustion Equipment
Certain turbines and miscellaneous gas- or liquid-fired units may also fall within the rule.
Equipment Below 325,000 BTU/hr
One important exemption is that Rule 1147 does not apply to units with a heat-input rating below 325,000 Btu/hr, subject to the rule’s other provisions. Charbroilers and food ovens are also specifically excluded.
This is one reason a facility should perform an equipment-by-equipment applicability review rather than assuming every combustion device is regulated identically.
Rule 1147 NOx & CO Limits
The rule uses different emission limits depending on:
- Equipment category
- Fuel type
- Process temperature
- Equipment age/status
- Applicable compliance schedule
For example, Table 2 includes requirements such as:
| Equipment Category | NOx Limit | CO Limit |
|---|---|---|
| Afterburner / Thermal Oxidizer / Catalytic Oxidizer / Vapor Incinerator | 20 ppmv or 0.024 lb/MMBtu | — |
| Burn-off Furnace / Burnout Oven / Incinerator / Crematory | 30 ppmv or 0.036 lb/MMBtu | — |
| Oven / Dryer / Heater / Kiln / Furnace <1,200°F | 20 ppmv or 0.024 lb/MMBtu | — |
| Oven / Dryer / Heater / Kiln / Furnace ≥1,200°F | 30 ppmv or 0.036 lb/MMBtu | — |
| Make-up Air Heater | 30 ppmv or 0.036 lb/MMBtu | — |
| Tenter/Fabric/Carpet Dryer | 20 ppmv or 0.024 lb/MMBtu | — |
| Autoclave | 30 ppmv or 0.036 lb/MMBtu | — |
| Liquid-Fueled Unit <1,200°F | 40 ppmv or 0.053 lb/MMBtu | 1,000 ppmv |
These are reference examples from Table 2, not a substitute for determining the limit applicable to a particular unit.
The “Less Than 1 Pound of NOx Per Day” Option
One of the important Rule 1147 compliance pathways allows an owner/operator to elect to demonstrate that NOx emissions are less than one pound per day averaged over a calendar month, subject to the rule’s requirements.
This can involve a non-resettable totalizing time meter or fuel meter and prescribed operating/fuel-use limits.
For example, the rule provides monthly operating-hour limits based on rated heat input for certain units:
- Below 1 MMBtu/hr: 240 hours/month
- 1 to below 1.5 MMBtu/hr: 160 hours/month
- 1.5 to 2 MMBtu/hr: 120 hours/month
The actual compliance pathway must be evaluated against the rule and facility conditions.
Rule 1147 Source Testing Requirements
This is where professional emissions testing becomes particularly important.
Rule 1147 requires applicable compliance determinations to use a South Coast AQMD-approved source-test protocol and test under specified operating conditions. Testing generally uses a period of at least 15 minutes and no more than 60 consecutive minutes, unless an alternative period is approved.
Testing must be performed after startup and at the unit’s normal firing rate.
For specified equipment categories, an additional compliance determination may be required at low heat input or during a specified period after startup.
Source-Test Protocol: A Critical Step
Don’t wait until the testing date to think about the protocol.
Rule 1147 requires the source-test protocol to be submitted to the Executive Officer for approval no later than 90 days before the scheduled source test.
Typical process:
Rule Review
↓
Equipment Review
↓
Test Protocol Development
↓
Protocol Submission
↓
Regulatory Approval
↓
Field Testing
↓
Data Analysis
↓
Compliance Report
This is one reason early scheduling is important.
Required Testing Frequency
For applicable units with NOx emissions ≥1 pound/day, Rule 1147 establishes source-testing frequencies based on rated heat input capacity:
Units <10 MMBtu/hr
Every 5 calendar years
Units ≥10 and <40 MMBtu/hr
Every 3 calendar years
Units ≥40 MMBtu/hr
Every calendar year
The rule also establishes minimum intervals between tests and special provisions for units that have been shut down for extended periods.
This makes one thing clear:
Knowing your last test date is not enough.
You need to know the rated heat input and applicable compliance category.
Who Can Conduct Rule 1147 Testing?
Rule 1147 requires applicable compliance determinations to be performed using an independent contractor approved by the Executive Officer under the Laboratory Approval Program for the applicable test methods.
This is an important consideration when selecting a testing company.
Before scheduling your test, verify:
- Appropriate test-method approval
- Qualified personnel
- Proper instrumentation
- Calibration procedures
- QA/QC
- South Coast AQMD experience
- Reporting capability
What Is Tested?
Depending on the equipment and compliance pathway, testing can involve:
NOx
The primary pollutant targeted by Rule 1147.
CO
Rule 1147 also establishes CO requirements for applicable equipment.
Oxygen
O₂ measurements are used in applicable emission calculations and correction procedures.
Carbon Dioxide
CO₂ may also be measured as part of applicable source-test procedures.
South Coast AQMD Method 100.1 and Method 10.1 are among the methods identified in Rule 1147 for applicable compliance determinations.
Rule 1147 Maintenance Requirements
Testing alone is not enough.
Rule 1147 requires owners/operators to perform combustion-system maintenance according to the manufacturer’s schedule and specifications and maintain the relevant records.
A strong compliance program therefore combines:
Testing + Tuning + Maintenance + Monitoring + Documentation
Recordkeeping Requirements
Rule 1147 requires certain records to be maintained for at least five years, including:
- Source-test reports
- Maintenance records
- Records supporting the less-than-one-pound-per-day pathway, when applicable
- Rated heat-input information
- Modification records
- Applicable CEMS records
- Manufacturer/distributor/maintenance-company schedules and instructions
Why does this matter?
Because compliance isn’t only about passing today’s test.
You may need to demonstrate your historical compliance during an inspection or regulatory review.
Rule 1147 Compliance: Pros
✅ Reduced NOx Emissions
The rule helps reduce NOx from miscellaneous combustion sources.
✅ Better Combustion Performance
Testing can identify inefficient combustion.
✅ Early Problem Detection
Emission testing can identify issues before they become major compliance problems.
✅ Better Documentation
Professional testing provides defensible technical records.
✅ Predictable Maintenance
Emission trends can help facilities plan maintenance.
✅ Environmental Benefits
Lower NOx emissions support regional air-quality objectives.
Rule 1147 Compliance: Challenges
❌ Testing Costs
Professional source testing requires specialized equipment and qualified personnel.
❌ Protocol Lead Time
Applicable protocols need to be planned and submitted well before testing.
❌ Equipment Downtime / Coordination
Testing must be coordinated with facility operations.
❌ Aging Burners
Older combustion systems may have difficulty meeting more stringent requirements.
❌ Retesting
If equipment fails, corrective action and additional testing may be necessary.
❌ Recordkeeping
Facilities must maintain compliance records for multiple years.
What Happens If Your Unit Fails?
A failed test doesn’t mean you should panic—but it does require prompt action.
Step 1 — Identify the Cause
Potential issues can include:
- Burner condition
- Fuel/air ratio
- Combustion controls
- Excess air
- Burner wear
- Maintenance problems
- Operating temperature
- Control-system performance
Step 2 — Correct the Problem
Tune, repair or modify the combustion system as appropriate.
Step 3 — Verify
Perform appropriate follow-up testing.
Step 4 — Document
Maintain:
- Test results
- Maintenance records
- Corrective actions
- Retest results
Step 5 — Maintain Compliance
Establish a monitoring and maintenance schedule to prevent repeat problems.
How EES Helps With Rule 1147 Compliance
Energy Environmental Solutions, Inc. (EES) can help industrial and commercial facilities manage the technical requirements associated with Rule 1147.
1. Rule Applicability Review
EES can review:
Equipment + Fuel + Rated Heat Input + Permit + Process Temperature + Applicable Regulation
to help identify the relevant compliance requirements.
2. NOx & CO Source Testing
EES can support applicable NOx and CO emissions testing using the appropriate approved procedures.
3. Source-Test Protocol Development
EES can help prepare protocols covering:
- Equipment information
- Applicable limits
- Test methods
- Operating conditions
- Sampling procedures
- QA/QC
- Calculations
- Reporting requirements
4. Compliance Testing
EES can coordinate field testing for applicable equipment and evaluate the resulting emissions data.
5. Combustion-System Compliance Support
Testing results can help identify whether burner tuning, maintenance or corrective action should be investigated.
6. Compliance Documentation
EES can assist with technical reports and organized documentation for your environmental compliance records.
7. Retesting & Corrective-Action Support
If results indicate an exceedance, EES can help facilities plan appropriate corrective testing.
EES Rule 1147 Compliance Process
1. REVIEW
Equipment + Permit + Rule Applicability
↓
2. PLAN
Testing Requirements + Applicable Limits
↓
3. PROTOCOL
Prepare & Submit Test Protocol
↓
4. TEST
NOx + CO + O₂ + Applicable Parameters
↓
5. ANALYZE
Validate Data & Calculate Results
↓
6. REPORT
Prepare Compliance Documentation
↓
7. FOLLOW UP
Corrective Action / Retesting if Required
Who Should Consider a Rule 1147 Compliance Review?
Potential clients include:
🏭 Manufacturing Facilities
🔥 Industrial Heating Operations
🧪 Chemical & Processing Facilities
🎨 Paint & Coating Operations
🚗 Automotive/Parts Manufacturing
🏺 Ceramic & Kiln Operations
♻️ Waste & Remediation Operations
🏢 Commercial Facilities
💧 Water/Wastewater Operations
⚙️ Facilities Using Thermal Oxidizers or Other Combustion Equipment
Applicability should always be confirmed based on the specific equipment and South Coast AQMD permit.
Rule 1147 Compliance Checklist for 2026
Before your next test, ask:
- Is my equipment subject to Rule 1147?
- Is the unit above 325,000 Btu/hr?
- What is its rated heat input?
- What fuel does it use?
- What is the process temperature?
- Is another Regulation XI rule applicable?
- What NOx limit applies?
- What CO limit applies?
- Does my unit emit ≥1 lb NOx/day?
- When was the last source test?
- When is the next test due?
- Is a source-test protocol required?
- Has the protocol been submitted on time?
- Is the testing contractor appropriately approved?
- Are combustion-maintenance records current?
- Are five years of compliance records available?
- Has the equipment been modified?
- Does the permit reflect the current equipment?
🚨 Don’t Wait Until Your Next Inspection
A compliance problem discovered at the last minute can create:
Testing delays + Maintenance Costs + Retesting + Production Disruption + Regulatory Risk
A proactive program gives you time to identify and correct problems.
EES Can Help You:
✔ Rule 1147 Applicability Review
✔ NOx Source Testing
✔ CO Testing
✔ Source-Test Protocol Development
✔ Combustion Compliance Testing
✔ Compliance Documentation
✔ Retesting Support
✔ Environmental Compliance Consulting
Ready for Rule 1147 Testing?
Is Your Combustion Equipment Ready for Its Next Compliance Test?
Don’t wait until your deadline is approaching.
Send EES:
📍 Facility Location
⚙️ Equipment Type
🔥 Fuel Type
📏 Rated Heat Input
🌡️ Operating Temperature
📄 Current Permit
📊 Last Source-Test Report
Request a Rule 1147 Compliance Review Today.
Test Your Emissions. Verify Your Compliance. Protect Your Operation.
Energy Environmental Solutions, Inc. (EES)
Phone: 714-630-5210 | 714-630-7844
Email: info@sourcetester.com
Website: sourcetester.org