Title 24 · California Energy Code
Acceptance testing, commissioning, certificates and Fault Detection & Diagnostics (FDD)
This hub summarizes where Title 24 (Part 6) requires acceptance testing, commissioning documentation, and FDD functional testing and certificates before occupancy.
Last reviewed: July 6, 2026
Overview
This area of the California Energy Code (Title 24, Part 6) governs acceptance testing, commissioning, and the Certificates of Acceptance required to document that HVAC, ventilation, controls and related systems meet code before occupancy. Acceptance testing and required certificates are specified in provisions such as §120.5 and §160.3 and implemented through the Reference Nonresidential Appendix tests (NA7 series), which list required functional tests for air economizers, DOAS, duct leakage, demand control ventilation, supply-fan and hydronic variable-flow controls, and FDD systems.
Fault Detection & Diagnostics (FDD) is treated both as an enforcement requirement (functional testing and Certificate of Acceptance when installed) and as an energy-performance option that can earn compliance credit when the installed FDD meets eligibility and functional-test criteria. Specific FDD test procedures and acceptance forms for packaged DX units and for AHUs/zone terminal units are detailed in the mechanical-code appendices (e.g., E 805 / MECH-12A and MECH-13A), which prescribe construction-inspection checks and step‑by‑step functional tests (low‑airflow, sensor disconnect, damper/actuator faults, refrigerant‑charge checks, etc.).
Practically, these rules mean mechanically demonstrating system installation and control operation—usually via the NA7 test procedures—and filing a signed Certificate of Acceptance with the enforcing agency before occupancy; where Title 24, Part 1 §10‑103.2 requires it, tests must be performed by a Certified Mechanical Acceptance Test Technician (CMATT).
In this section
Code references
Grounded in the retrieved California Energy Code — click a citation to read the verbatim passage:
§ 805.11.2 High relevance — show source text
Step 1: Engage the global demand shed system. Verify and document the following:
(1) That the cooling setpoint in noncritical spaces increases by the proper amount.
(2) That the cooling setpoint in critical spaces do not change.
Step 2: Disengage the global demand shed system. Verify and document the following:
(1) That the cooling setpoint in noncritical spaces return to their original values.
(2) That the cooling setpoint in critical spaces do not change.
E 805.11.2 Acceptance Criteria. The control system changes the setpoints of noncritical zones on activation of a single central hardware or software point then restores the initial setpoints where the point is released.
E 805.12 Fault Detection and Diagnostics (FDD) for Packaged Direct-Expansion (DX) Units (Form MECH-12A). The purpose of this test is to verify proper fault detection and reporting for automated fault detection and diagnostics systems for packaged units. Automated FDD systems ensure proper equipment operation by identifying and diagnosing common equipment problems such as improper refrigerant charge, low airflow, or faulty economizer operation. Qualifying FDD systems receive a compliance credit where using the performance approach. A system that does not meet the eligibility requirements shall be permitted to be installed, but no compliance credit will be given.
E 805.12.1 Test Procedure. The procedure for performing a functional test for fault detection and diagnostics (FDD) for packaged direct-expansion (DX) units shall be in accordance with Section E 805.12.1.1 and
Section E 805.12.1.2.
E 805.12.1.1 Construction Inspection. Prior to functional testing, verify and document that the FDD
hardware is installed on equipment by the manufacturer, and that equipment make and model include factory-installed FDD hardware that match the information indicated on copies of the manufacturer’s cut sheets and on the plans and specifications.
This procedure applies to fault detection and diagnostics (FDD) system for direct-expansion packaged units containing the following features:
(1) The unit shall include a factory-installed economizer and shall limit the economizer dead band to not more than 2°F (-17°C).
(2) The unit shall include direct-drive actuators on outside air and return air dampers.
(3) The unit shall include an integrated economizer with either differential dry-bulb or differential enthalpy control.
(4) The unit shall include a low temperature lockout on the compressor to prevent coil freeze-up or comfort problems.
(5) Outside air and return air dampers shall have maximum leakage rates in accordance to this appendix.
(6) The unit shall have an adjustable expansion control device such as a thermostatic expansion valve (TXV).
(7) To improve the ability to troubleshoot charge and compressor operation, a high-pressure refrigerant port will be located on the liquid line. A low-pressure refrigerant port will be located on the suction line.
(8) The following sensors shall be permanently installed to monitor system operation, and the controller shall have the capability of displaying the value of each parameter:
(a) Refrigerant suction pressure
(b) Refrigerant suction temperature
(c) Liquid line pressure
(d) Liquid line temperature
(e) Outside air temperature
(f) Outside air relative humidity
(g) Return air temperature
(h) Return air relative humidity
(i) Supply air temperature
(j) Supply air relative humidity
§ 805.12.1.2 High relevance — show source text
(1) Compressor enabled
(2) Economizer enabled
(3) Free cooling available
(4) Mixed air low limit cycle active
(5) Heating enabled
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APPENDIX E
The unit controller shall have the capability to manually initiate each operating mode so that the operation of compressors, economizers, fans, and heating system can be independently tested and verified.
E 805.12.1.2 Functional Testing. The functional testing shall be in accordance with the following steps:
Step 1: Test low airflow condition by replacing the existing filter with a dirty filter or appropriate obstruction.
Step 2: Verify that the fault detection and diagnostics system reports the fault.
Step 3: Verify that the system is able to verify the correct refrigerant charge.
Step 4: Calibrate outside air, return air, and supply air temperature sensors. E 805.12.2 Acceptance Criteria. The system is able to detect a low airflow condition and report the fault. The system is able to detect where refrigerant charge is low or high and the fault is reported. E 805.13 Automatic Fault Detection Diagnostics (FDD) for Air Handling Units (AHU) and Zone Termi- nal Units (Form MECH-13A). The purpose of this test is to verify that the system detects common faults in air handling units and terminal units. FDD systems for air handling units and zone terminal units require DDC controls to the zone level. Successful completion of this test provides a compliance credit where using the performance approach. An FDD system that does not pass this test shall be permitted to be installed, but no compliance credit will be given. E 805.13.1 Test Procedure. The procedure for performing a functional test for automatic fault detection diagnostics (FDD) for air handling units and zone terminal units shall be in accordance with Section E 805.13.1.1.
E 805.13.1.1 Functional Testing. The functional testing shall be in accordance with Section E 805.13.1.1.1 and Section E 805.13.1.1.2.
E 805.13.1.1.1 Functional Testing for Air Handling Units. The functional testing of AHU with FDD controls shall be in accordance with the following steps:
Step 1: Sensor drift/failure:
(1) Disconnect outside air temperature sensor from unit controller.
(2) Verify that the FDD system reports a fault.
(3) Connect OAT sensor to the unit controller.
(4) Verify that FDD indicates normal system operation.
Step 2: Damper/actuator fault:
(1) From the control system workstation, command the mixing box dampers to full open (100 percent outdoor air).
(2) Disconnect power to the actuator and verify that a fault is reported at the control workstation.
(3) Reconnect power to the actuator and command the mixing box dampers to full open.
(4) Verify that the control system does not report a fault.
(5) From the control system workstation, command the mixing box dampers to a fullclosed position (0 percent outdoor air).
(6) Disconnect power to the actuator and verify that a fault is reported at the control workstation.
§ 805.10.2 High relevance — show source text
(3) System operation shall stabilize within 5 minutes after test procedures are initiated.
Step 2: Modulate control valves to reduce water flow to 50 percent of the design flow or less, but not lower than the pump minimum flow. Verify and document the following:
(1) Pump speed decrease.
(2) Current operating setpoint has decreased (for systems with DDC to the zone level).
(3) Current operating setpoint has not increased (for all other systems).
(4) System pressure is within 5 percent of current operating setpoint.
(5) System operation stabilizes within 5 minutes after test procedures are initiated.
2025 CALIFORNIA MECHANICAL CODE 487
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APPENDIX E
E 805.10.2 Acceptance Criteria. The differential pressure sensor is either factory calibrated (with calibration certificates) or field calibrated. The pressure sensor shall be located at or near the most remote HX or control valve. The setpoint system controls shall stabilize.
E 805.11 Automatic Demand Shed Control (Form MECH-11A). The purpose of this test is to ensure that the central demand shed sequences have been properly programmed into the DDC system.
E 805.11.1 Test Procedure. The procedure for performing a functional test for automatic demand shed controls shall be in accordance with Section E 805.11.1.1
and Section E 805.11.1.2.
E 805.11.1.1 Construction Inspection. Prior to functional testing, verify and document that the EMCS interface enables activation of the central
demand shed controls.
E 805.11.1.2 Functional Testing. The functional testing shall comply with the following steps:
Step 1: Engage the global demand shed system. Verify and document the following:
(1) That the cooling setpoint in noncritical spaces increases by the proper amount.
(2) That the cooling setpoint in critical spaces do not change.
Step 2: Disengage the global demand shed system. Verify and document the following:
(1) That the cooling setpoint in noncritical spaces return to their original values.
(2) That the cooling setpoint in critical spaces do not change.
E 805.11.2 Acceptance Criteria. The control system changes the setpoints of noncritical zones on activation of a single central hardware or software point then restores the initial setpoints where the point is released.
E 805.12 Fault Detection and Diagnostics (FDD) for Packaged Direct-Expansion (DX) Units (Form MECH-12A). The purpose of this test is to verify proper fault detection and reporting for automated fault detection and diagnostics systems for packaged units. Automated FDD systems ensure proper equipment operation by identifying and diagnosing common equipment problems such as improper refrigerant charge, low airflow, or faulty economizer operation. Qualifying FDD systems receive a compliance credit where using the performance approach. A system that does not meet the eligibility requirements shall be permitted to be installed, but no compliance credit will be given.
E 805.12.1 Test Procedure. The procedure for performing a functional test for fault detection and diagnostics (FDD) for packaged direct-expansion (DX) units shall be in accordance with Section E 805.12.1.1 and
Section E 805.12.1.2.
§ 5.1. High relevance — show source text
(a) Before an occupancy permit is granted, the following equipment and systems shall be certified as meeting the Acceptance Requirements for Code Compliance, as specified by the Reference Nonresidential Appendix NA7. A Certificate of Acceptance shall be submitted to the enforcement agency that certifies that the equipment and systems meet the acceptance requirements:
Outdoor air ventilation systems shall be tested in accordance with NA7.5.1.
Constant volume, single zone unitary air conditioning and heat pump unit controls shall be tested in accordance with NA7.5.2.
Duct systems that are subject to testing under Section 120.4(g)1, Section 141.0(b)2Di or Section 141.0(b)2Dii shall be tested in accordance with NA7.5.3.
Air economizers, DOAS, HRV or ERV systems shall be tested in accordance with NA7.5.4. Exception 1 to Section 120.5(a)4: Air economizers installed by the HVAC system manufacturer and certified to the Commission as being factory calibrated and tested are not required to comply with the Functional Testing section of the air economizer controls acceptance test as described in NA7.5.4.2. Exception 2 to Section 120.5(a)4: The DOAS, HRV, or ERV unit that does not meet the exhaust air heat recovery ratio as specified in Section 140.4(q)1 or does not include bypass or control to disable energy recovery as specified in Section 140.4(q)2.
Demand control ventilation systems required by Section 120.1(c)3 shall be tested in accordance with NA7.5.5.
Supply fan variable flow controls shall be tested in accordance with NA7.5.6.
Hydronic system variable flow controls shall be tested in accordance with NA7.5.7 and NA7.5.9.
Boiler or chillers that require isolation controls as specified by Section 140.4(k)2 or 140.4(k)3 shall be tested in accordance with NA7.5.7.
Hydronic systems with supply water temperature reset controls shall be tested in accordance with NA7.5.8.
Automatic demand shed controls shall be tested in accordance with NA7.5.10.
Fault Detection and Diagnostics (FDD) for Packaged Direct-Expansion Units shall be tested in accordance with NA7.5.11.
Automatic fault detection and diagnostics (FDD) for air handling units and zone terminal units shall be tested in accordance with NA7.5.12.
Distributed Energy Storage DX AC Systems shall be tested in accordance with NA7.5.13.
Thermal Energy Storage (TES) Systems shall be tested in accordance with NA7.5.14.
Supply air temperature reset controls shall be tested in accordance with NA7.5.15.
Water-cooled chillers served by cooling towers with condenser water reset controls shall be tested in accordance with NA7.5.16.
When an energy management control system is installed, it shall functionally meet all of the applicable requirements of Part 6.
Occupant sensing zone controls shall be tested in accordance with NA7.5.17.
Conductivity controls and overflow alarms for open and closed-circuit cooling towers shall be tested according to NA7.5.18.
§ 160.3 High relevance — show source text
(d) Mechanical acceptance testing.
- Common areas. Before an occupancy permit is granted, the following systems and equipment serving multifamily common areas shall be certified as meeting the Acceptance Requirements for Code Compliance, as specified by Reference Nonresidential Appendix NA7. These systems and equipment shall also comply with the applicable requirements of Section
220 2025 CALIFORNIA ENERGY CODE
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MULTIFAMILY BUILDINGS—MANDATORY REQUIREMENTS
160.3(d)3. A Certificate of Acceptance shall be submitted to the enforcement agency that certifies that the equipment and systems meet the acceptance requirements: A. Outdoor air ventilation systems shall be tested in accordance with NA7.5.1. B. Constant volume, single zone air conditioning and heat pump unit controls shall be tested in accordance with NA7.5.2. C. Duct systems shall be tested in accordance with NA7.5.3 where either: a. They are new duct systems; or b. They are part of an altered system. D. Air economizers, DOAS, HRV or ERV systems shall be tested in accordance with NA7.5.4. Exception to Section 160.3(d)1D: Air economizers installed by the HVAC system manufacturer and certified to the Commission as being factory calibrated and tested are not required to comply with the Functional Testing section of the Air Economizer Controls acceptance test as described in NA7.5.4.2. E. Demand control ventilation systems required by Section 160.2(c)3 shall be tested in accordance with NA7.5.5. F. Supply fan variable flow controls shall be tested in accordance with NA7.5.6. G. Hydronic system variable flow controls shall be tested in accordance with NA7.5.7 and NA7.5.9. H. Boilers or chillers that require isolation controls as specified by Section 170.2(c)4Iii or 170.2(c)4Iiii shall be tested in accordance with NA7.5.7.
I. Hydronic systems with supply water temperature reset controls shall be tested in accordance with NA7.5.8.
J. Automatic demand shed controls shall be tested in accordance with NA7.5.10.
K. Fault detection and diagnostics (FDD) for packaged direct expansion units shall be tested in accordance with NA7.5.11. L. Automatic fault detection and diagnostics (FDD) for air handling units and zone terminal units shall be tested in accordance with NA7.5.12.
M. Distributed energy storage DX AC systems shall be tested in accordance with NA7.5.13. N. Thermal energy storage (TES) systems shall be tested in accordance with NA7.5.14. O. Supply air temperature reset controls shall be tested in accordance with NA7.5.15. P. Water-cooled chillers served by cooling towers with condenser water reset controls shall be tested in accordance with NA7.5.16.
Q. When an energy management control system is installed, it shall functionally meet all of the applicable requirements of Part 6.
§ 5.6. High relevance — show source text
Supply fan variable flow controls shall be tested in accordance with NA7.5.6.
Hydronic system variable flow controls shall be tested in accordance with NA7.5.7 and NA7.5.9.
Boiler or chillers that require isolation controls as specified by Section 140.4(k)2 or 140.4(k)3 shall be tested in accordance with NA7.5.7.
Hydronic systems with supply water temperature reset controls shall be tested in accordance with NA7.5.8.
Automatic demand shed controls shall be tested in accordance with NA7.5.10.
Fault Detection and Diagnostics (FDD) for Packaged Direct-Expansion Units shall be tested in accordance with NA7.5.11.
Automatic fault detection and diagnostics (FDD) for air handling units and zone terminal units shall be tested in accordance with NA7.5.12.
Distributed Energy Storage DX AC Systems shall be tested in accordance with NA7.5.13.
Thermal Energy Storage (TES) Systems shall be tested in accordance with NA7.5.14.
Supply air temperature reset controls shall be tested in accordance with NA7.5.15.
Water-cooled chillers served by cooling towers with condenser water reset controls shall be tested in accordance with NA7.5.16.
When an energy management control system is installed, it shall functionally meet all of the applicable requirements of Part 6.
Occupant sensing zone controls shall be tested in accordance with NA7.5.17.
Conductivity controls and overflow alarms for open and closed-circuit cooling towers shall be tested according to NA7.5.18.
(b) When certification is required by Title 24, Part 1, Section 10-103.2, the acceptance testing specified by Section 120.5(a) shall be performed by a certified mechanical acceptance test technician (CMATT). If the CMATT is operating as an employee, the CMATT shall
2025 CALIFORNIA ENERGY CODE 79
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NONRESIDENTIAL, HOTEL/MOTEL OCCUPANCIES, AND COVERED PROCESSES—MANDATORY REQUIREMENTS
be employed by a certified mechanical acceptance test employer. The CMATT shall disclose on the certificate of acceptance a valid CMATT certification identification number issued by an approved acceptance test technician certification provider. The CMATT shall complete all certificate of acceptance documentation in accordance with the applicable requirements in Section 10-103(a)4.
Note: Authority cited: Sections 25213, 25218, 25218.5, 25402 and 25402.1, Public Resources Code. Reference: Sections 25007, 25008, 25218.5, 25310, 25402(a)-(b), 25402.1, 25402.4, 25402.5, 25402.8 and 25943, Public Resources Code .
SECTION 120.6—MANDATORY REQUIREMENTS FOR COVERED PROCESSES
Nonresidential and hotel/motel buildings shall comply with the applicable requirements of Sections 120.6(a) through 120.6(k), and the applicable requirements of Sections 110.2(a) and 120.3.
(a) Mandatory requirements for refrigerated warehouses.
§ 160.2 High relevance — show source text
E. Demand control ventilation systems required by Section 160.2(c)3 shall be tested in accordance with NA7.5.5. F. Supply fan variable flow controls shall be tested in accordance with NA7.5.6. G. Hydronic system variable flow controls shall be tested in accordance with NA7.5.7 and NA7.5.9. H. Boilers or chillers that require isolation controls as specified by Section 170.2(c)4Iii or 170.2(c)4Iiii shall be tested in accordance with NA7.5.7.
I. Hydronic systems with supply water temperature reset controls shall be tested in accordance with NA7.5.8.
J. Automatic demand shed controls shall be tested in accordance with NA7.5.10.
K. Fault detection and diagnostics (FDD) for packaged direct expansion units shall be tested in accordance with NA7.5.11. L. Automatic fault detection and diagnostics (FDD) for air handling units and zone terminal units shall be tested in accordance with NA7.5.12.
M. Distributed energy storage DX AC systems shall be tested in accordance with NA7.5.13. N. Thermal energy storage (TES) systems shall be tested in accordance with NA7.5.14. O. Supply air temperature reset controls shall be tested in accordance with NA7.5.15. P. Water-cooled chillers served by cooling towers with condenser water reset controls shall be tested in accordance with NA7.5.16.
Q. When an energy management control system is installed, it shall functionally meet all of the applicable requirements of Part 6.
R. Occupant sensing zone controls shall be tested in accordance with NA7.5.17. 2. Multifamily dwelling units. Before an occupancy permit is granted, the following systems and equipment serving multifamily dwelling units shall be certified as meeting the acceptance requirements for code compliance, as specified by the Reference Nonresidential Appendix NA7. These systems and equipment shall also comply with the applicable requirements of Section 160.3(d)3. A Certificate of Acceptance shall be submitted to the enforcement agency that certifies that the equipment and systems meet the acceptance requirements: A. Multifamily building central ventilation ducts subject to Section 160.2(b)2C shall be leak tested in accordance with NA7.18.3.
B. Multifamily building central ventilation system heat recovery or energy recovery systems in multifamily buildings with four or more habitable stories shall be tested in accordance with NA7.18.4.
- When certification is required by Title 24, Part 1, Section 10-103.2, the acceptance testing specified by Section 160.3(d)1 and 2 shall be performed by a Certified Mechanical Acceptance Test Technician (CMATT). If the CMATT is operating as an employee, the CMATT shall be employed by a Certified Mechanical Acceptance Test Employer. The CMATT shall disclose on the Certificate of Acceptance a valid CMATT certification identification number issued by an approved Acceptance Test Technician Certification Provider. The CMATT shall complete all Certificate of Acceptance documentation in accordance with the applicable requirements in Section 10-103(a)4.
TABLE 160.3-A—RETURN DUCT SIZING FOR SINGLE RETURN DUCT SYSTEMS Col2 Col3 Return duct length shall not exceed 30 feet and shall contain no more than 180 degrees of bend. § 801.0 High relevance — show source text
I certify that the information provided on this form substantiates that the construction/installation identified on this form complies with the acceptance requirements indicated in the plans and specifications approved by the enforcement agency, and conforms to the applicable acceptance requirements and procedures specified in Section E 801.0 through Section E 806.0.
I have confirmed that the Installation Certificate(s) for the construction/installation identified on this form has been completed and is posted or made available with the permit(s) issued for the building.
I will ensure that a completed, signed copy of this Certificate of Acceptance shall be posted, or made available with the building permit(s) issued for the building, and made available to the enforcement agency for all applicable inspections. I understand that a signed copy of this Certificate of Acceptance is required to be included with the documentation the builder
provides to the building owner at occupancy. Col2 Col3 Col4
Company Name:
Company Name:
Company Name:Phone:
Responsible Person’s Name:
Responsible Person’s Name:Responsible Person’s Signature: Responsible Person’s Signature:
License:Date Signed: Position With Company (Title): Position With Company (Title): 2025 CALIFORNIA MECHANICAL CODE 519
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APPENDIX E
CERTIFICATE OF ACCEPTANCE MECH-12A Col2
Fault Detection and Diagnostics (FDD) for Packaged Direct-Expansion Units
(Page 2 of 3)
Fault Detection and Diagnostics (FDD) for Packaged Direct-Expansion Units
(Page 2 of 3)
Project Name/Address:
Project Name/Address:System Name or Identification/Tag: System Location or Area Served: The purpose of this test is to verify proper fault detection and reporting for automated fault detection and Intent: diagnostics systems for packaged units.
Construction Inspection
- Instrumentation to perform test includes, but not limited to: a. List of instrumentation may be needed or included.
- Installation.
Verify that FDD hardware is installed on equipment by the manufacturer and that equipment make and model include factory-installed FDD hardware that matches the information indicated on copies of the manufacturer’s cut sheets and on the plans and specifications.
A. Eligibility Criteria Results. Results Col2
a.
A fault detection and diagnostics (FDD) system for direct-expansion packaged units shall contain the following
features to be eligible for credit in the performance calculation method:
a.
A fault detection and diagnostics (FDD) system for direct-expansion packaged units shall contain the following
features to be eligible for credit in the performance calculation method:
b.
The unit shall include a factory-installed economizer and shall limit the economizer dead band to no
more than 2°F.Y / N
c.
The unit shall include direct-drive actuators on outside air and return air dampers.CMC § 522 Medium relevance — show source text
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APPENDIX E
CERTIFICATE OF ACCEPTANCE MECH-13A Col2
Automatic Fault Detection and Diagnostics (FDD) for Packaged Direct-Expansion Units and Zone
(Page 2 of 4)
Terminal Units Acceptance
Automatic Fault Detection and Diagnostics (FDD) for Packaged Direct-Expansion Units and Zone
(Page 2 of 4)
Terminal Units Acceptance
Project Name/Address:
Project Name/Address:System Name or Identification/Tag: System Location or Area Served: Intent: Verify that the system detects common faults in air handling units and zone terminal units.
Construction Inspection
- Instrumentation to perform test includes, but not limited to: a. No instrumentation is required – changes are implemented at the building automation system control station.
- Installation.
a. The functional testing verifies proper installation of the controls for FDD for air handling units and zone terminal units. No additional installation checks are required.
A. Eligibility Criteria Results. Results
Testing of each AHU with FDD controls shall include the following tests:
Testing of each AHU with FDD controls shall include the following tests:
Step 1: Sensor Drift/Failure:
Step 1: Sensor Drift/Failure:
a.
Disconnect outside air temperature sensor from unit controller.Y / N
b.
Verify that the FDD system reports a fault.Y / N
c.
Connect OAT sensor to the unit controller.Y / N
d.
Verify that FDD indicates normal system operation.Y / NStep 2: Damper/actuator fault. Step 2: Damper/actuator fault.
a.
From the control system workstation, command the mixing box dampers to full open (100% outdoor
air).Y / N
b.
Disconnect power to the actuator and verify that a fault is reported at the control workstation.Y / N
c.
Reconnect power to the actuator and command the mixing box dampers to full open.Y / N
d.
Verify that the control system does not report a fault.Y / N
e.
From the control system workstation, command the mixing box dampers to a full-closed position
(0% outdoor air).Y / N
f.
Disconnect power to the actuator and verify that a fault is reported at the control workstation.Y / N
g.
Reconnect power to the actuator and command the dampers closed.CMC § 2025 Medium relevance — show source text
Reconnect power to the actuator and command the dampers closed.|Y / N
| |
h.
Verify that the control system does not report a fault during normal operation.|Y / N| |Step 3: Valve/actuator fault.
|Step 3: Valve/actuator fault.
| |
a.
From the control system workstation, command the heating and cooling coil valves to full open or
closed, then disconnect power to the actuator and verify that a fault is reported at the control workstation.|Y / N| |
Step 4: Inappropriate simultaneous heating, mechanical cooling, and/or economizing.
|
Step 4: Inappropriate simultaneous heating, mechanical cooling, and/or economizing.
| |
a.
From the control system workstation, override the heating coil valve and verify that a fault is
reported at the control workstation.|Y / N
| |
b.
From the control system workstation, override the cooling coil valve and verify that a fault is
reported at the control workstation.|Y / N
| |
c.
From the control system workstation, override the mixing box dampers and verify that a fault is
reported at the control workstation.|Y / N|2025 CALIFORNIA MECHANICAL CODE 523
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APPENDIX E
CERTIFICATE OF ACCEPTANCE MECH-13A Col2
Automatic Fault Detection and Diagnostics (FDD) for Packaged Direct-Expansion Units and Zone
(Page 3 of 4)
Terminal Units Acceptance
Automatic Fault Detection and Diagnostics (FDD) for Packaged Direct-Expansion Units and Zone
(Page 3 of 4)
Terminal Units Acceptance
Project Name/Address:
Project Name/Address:
System Name or Identification/Tag:System Location or Area Served: B. Functional Testing for Zone Terminal Units. Results
Testing shall be performed on one of each type of terminal unit (VAV box) in the project. A
minimum of 5% of results the terminal boxes shall be tested.
Testing shall be performed on one of each type of terminal unit (VAV box) in the project. A
**minimum of 5% of results the terminal boxes shall be tested.CMC § 2025 Medium relevance — show source text
2025 CALIFORNIA MECHANICAL CODE 523
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APPENDIX E
CERTIFICATE OF ACCEPTANCE MECH-13A Col2
Automatic Fault Detection and Diagnostics (FDD) for Packaged Direct-Expansion Units and Zone
(Page 3 of 4)
Terminal Units Acceptance
Automatic Fault Detection and Diagnostics (FDD) for Packaged Direct-Expansion Units and Zone
(Page 3 of 4)
Terminal Units Acceptance
Project Name/Address:
Project Name/Address:
System Name or Identification/Tag:System Location or Area Served: B. Functional Testing for Zone Terminal Units. Results
Testing shall be performed on one of each type of terminal unit (VAV box) in the project. A
minimum of 5% of results the terminal boxes shall be tested.
Testing shall be performed on one of each type of terminal unit (VAV box) in the project. A
minimum of 5% of results the terminal boxes shall be tested.Step 1: Sensor Drift/Failure: Step 1: Sensor Drift/Failure:
a.
Disconnect the tubing to the differential pressure sensor of the VAV box.Y / N
b.
Verify that control system detects and reports the fault.Y / N
c.
Reconnect the sensor and verify proper sensor operation.Y / N
d.
Verify that the control system does not report a fault.Y / N
Step 2: Damper/actuator fault.
Step 2: Damper/actuator fault.If the damper is stuck open:If the damper is stuck open:
a.
Command the damper to be fully open (room temperature above setpoint).Y / N
b.
Disconnect the actuator to the damper.Y / N
c.
Adjust the cooling setpoint so that the room temperature is below the cooling setpoint to command
the damper to the minimum position.
Frequently asked questions
Who must sign and submit a Certificate of Acceptance, and when?
A completed, signed Certificate of Acceptance must be posted or made available with the building permit and submitted to the enforcement agency prior to occupancy; when Part 1 §10‑103.2 applies the acceptance testing must be performed by a CMATT and the CMATT ID disclosed on the certificate.
Does installing FDD relieve me of acceptance testing?
No. Installed FDD systems must still undergo the applicable acceptance tests (NA7.5.11 for packaged DX units and NA7.5.12 for AHUs/zone terminals) and a Certificate of Acceptance; eligible FDD systems that pass the tests may earn performance‑path credit, but systems that fail are still permitted to be installed (without the credit).
What kinds of FDD functional checks are performed?
Typical functional tests include low‑airflow simulation, sensor‑drift/disconnect checks, damper/actuator and valve fault injections, refrigerant‑charge verification, and checks for simultaneous heating/cooling or economizing faults—procedures laid out in the MECH‑12A / MECH‑13A forms and E 805 series.
More in California Energy Code
- Compliance paths, energy budgets, performance modeling and forms/software requirements
- Controls, commissioning, demand-response, sensors, and field verification/diagnostic testing
- Domestic hot water systems, efficiency, controls and installation requirements
- Electrical infrastructure, EV charging readiness, load management and demand controls
- Envelope construction, insulation, fenestration and thermal performance
- HVAC systems, ventilation rates, ducting, controls and testing
- Interior and exterior lighting power, controls and daylighting requirements
- Mandatory measures, appliance efficiency and certification requirements
- Photovoltaic requirements, BESS (battery energy storage) sizing and SARA procedures
- Reference appendices, test procedures, product certification and labeling requirements
- Scope, applicability, definitions and administrative requirements
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