Title 24 · California Energy Code
When must field verification and diagnostic testing be performed for residential HVAC and ventilation?
If you alter or install HVAC or dwelling ventilation equipment in California, field verification and diagnostic testing (FVDT) is required whenever the Code requires proof of correct refrigerant charge, minimum airflow, duct sealing, or ventilation fan performance. The controlling rules are in §150.2(b) for alterations and §160.2/§160.3 for dwelling ventilation and system airflow/fan efficacy; the measurements must follow the Reference Residential Appendix procedures (RA3.x) and, where required, be verified by an ECC‑Rater. file
Last reviewed: July 6, 2026
What the code requires — plain English
Field Verification and Diagnostic Testing (FVDT) is required whenever the California Energy Code requires confirmation of minimum system airflow, refrigerant charge, duct sealing, whole‑dwelling ventilation airflow, or fan efficacy for dwelling-unit HVAC or ventilation systems. The controlling provisions are § 150.2(b) (alterations/repairs) and the dwelling‑unit requirements in § 160.2 and § 160.3; the Code requires FVDT to be done using the procedures in the Reference Residential Appendices (for example RA3.2, RA3.3, RA3.7) and verified by an ECC‑Rater or as otherwise allowed by the exceptions.
The single most important rule: perform FVDT when the Code calls for confirmation of airflow, refrigerant charge, duct leakage, or ventilation fan efficacy — follow the RA procedures and have the ECC‑Rater verify where specified.
Requirements in detail
1) When § 150.2(b) (Alterations) triggers FVDT
- When a space‑conditioning system is altered by replacing refrigerant‑containing components (compressor, condensing coil, evaporator coil, metering device or refrigerant piping), the altered system must comply with the refrigerant verification, minimum airflow, and related FVDT requirements in § 150.2(b) and the referenced RA procedures.
- When more than 25 ft of new or replacement ducts are installed the altered duct system must be sealed and the sealing confirmed by FVDT (see duct leakage criteria).
2) When § 160.2 / § 160.3 (Dwelling ventilation & system airflow/fan efficacy) trigger FVDT
- Whole‑dwelling ventilation airflow required by § 160.2(b) shall be confirmed by FVDT in accordance with RA3.7.4 (or NA procedures for taller buildings). Balanced systems: average supply and exhaust flows are used. Ventilation systems with multiple operating modes must be tested in all modes used for compliance.
- System airflow rate and air‑handler fan efficacy requirements for central forced‑air systems (single‑zone, zonal, small‑duct, central‑fan ventilation) are confirmed by FVDT per RA3.3, including requirements for a static pressure probe hole or permanent probe location.
3) Refrigerant charge verification — when and how
- When refrigerant charge verification is required by the applicable tables/sections, the installer must verify charge either with the standard charge procedure (RA3.2.2) or the weigh‑in procedure (RA3.2.3.1), and an ECC‑Rater must verify the result per the RA procedures (RA3.2.3.2 or RA3.2.2 verification flow). Packaged systems precharged and certified by the manufacturer prior to shipment are excepted from field verification but must be certified by the installer on the Certificate of Installation.
Decision‑relevant table (quick reference)
| Decision / threshold | Value / action required | Code Reference |
|---|---|---|
| Minimum airflow — altered systems (small‑duct HV) | ≥ 250 cfm/ton (test by FVDT per RA3.3) | § 150.2(b)1Fiia |
| Minimum airflow — altered systems (other air‑cooled / air‑source) | ≥ 300 cfm/ton (test by FVDT per RA3.3) | § 150.2(b)1Fiia |
| Minimum airflow — new single‑zone central forced‑air | ≥ 350 cfm/ton (test by FVDT per RA3.3) | § 150.0 / § 160.3 / § 150.1(c) file |
| Fan efficacy — gas furnace AHU | ≤ 0.45 W/cfm (confirm via FVDT) | § 160.3(b)5Lii / § 150.0(m) file |
| Fan efficacy — non‑gas‑furnace AHU | ≤ 0.58 W/cfm (confirm via FVDT) | § 160.3(b)5Lii |
| Fan efficacy — small‑duct HV | ≤ 0.62 W/cfm (confirm via FVDT) | § 160.3(b)5Liv |
| HRV/ERV fan efficacy (single dwelling) | ≤ 1.0 W/cfm (confirm via FVDT per RA3.7.4.4) | § 160.2(b)2Biii |
| Duct leakage – altered ducts (>25 ft) | Leakage limits vary (see leakage options in code; FVDT required) | § 150.2(b)1D / RA3.1 |
| Refrigerant charge verification method | RA3.2.2 (standard) or RA3.2.3.1 (weigh‑in) with ECC‑Rater verification per RA3.2.3.2 | § 150.2(b) / § 150.1 / RA3 file |
(Each row above is enforced by the cited Code subsection and requires the referenced RA FVDT procedures.) file
4) Who must perform / verify the FVDT
- Installers perform the required measurements and adjustments per the RA procedures, but ECC‑Raters (or an allowed alternative acceptance tester in some multifamily cases) must verify many of the refrigerant and airflow checks and enter registry data where required. The Code provides alternate NA procedures and limited exemptions for buildings with four or more habitable stories. file
Exceptions & special cases
- Precharged packaged systems: If the manufacturer certifies the packaged unit was precharged at the factory and it has not been altered, on‑site refrigerant charge confirmation by FVDT is not required; the installer must certify that on the Certificate of Installation.
- Systems that cannot provide measurement access holes (MAH): The Code exempts systems that cannot conform to MAH/hole specifications from having holes (but other verification methods apply).
- Outdoor temperature < 55°F: If the installer uses the weigh‑in procedure in RA3.2.3.1 when outdoor temperature is <55°F, an alternative RA verification (RA3.2.3.2) may be used subject to thermostat restrictions (see § 110.12).
- Multispeed / variable‑speed systems: May be verified in the mode required by the code (often at maximum compressor/fan speed) per the specific exception language — e.g., demonstrate airflow and fan efficacy at maximum compressor and fan speed.
- Multifamily buildings: For buildings with four or more habitable stories, some FVDT and ECC‑Provider registry requirements in RA2/RA3 are waived and allow alternative testers/certifications per the NA appendices. file
Common mistakes
- Assuming one airflow threshold fits all: 350 cfm/ton, 300 cfm/ton, and 250 cfm/ton all appear in the Code — apply the correct threshold for new vs altered systems and for small‑duct HV vs other systems. file
- Testing only one control mode: zonal and multispeed systems must be tested in every control mode necessary to demonstrate compliance (or at the mode specified by the exceptions).
- Forgetting to average balanced ventilation supply and exhaust flows when verifying whole‑dwelling performance.
- Not involving an ECC‑Rater when the RA procedures require ECC‑Rater verification (especially for refrigerant weigh‑in verification).
- Overlooking the packaged‑system exception — some precharged packaged units do not require field charge verification but require installer certification on the installation form.
Worked example — concrete scenario with numbers
Scenario: You replace the compressor in a 3‑ton ducted split heat pump serving a single‑family dwelling (alteration). The system is not a small‑duct high‑velocity type.
Apply § 150.2(b) altered‑system rules: minimum system airflow requirement for "all other" air‑cooled/air‑source systems is ≥ 300 cfm/ton for altered systems, so required airflow = 3 tons × 300 cfm/ton = 900 cfm. Confirm by FVDT per RA3.3.
Installer performs airflow measurements at return grille(s) and obtains 820 cfm. That is below the required 900 cfm → not compliant. Per the code the installer must either bring airflow up to meet the requirement (repair/adjust ducting, fan speed, clean/replace filters consistent with design pressure drop) or follow the RA exception pathway (e.g., RA3.3.3.1.5 procedures for systems unable to meet the minimum airflow) and ensure the thermostat meets § 110.12 if using the RA exception. file
Refrigerant: because refrigerant‑containing components were replaced, refrigerant charge verification is required. Installer uses the weigh‑in procedure RA3.2.3.1 and the ECC‑Rater verifies the weigh‑in via RA3.2.3.2. If the manufacturer had precharged the packaged unit before shipment, the installer could instead certify that the charge was not altered (not applicable here). file
Recordkeeping: ECC‑Rater verification and Certificate of Installation entries are completed and any registry reporting required by RA2/RA3 is performed unless a multifamily/story exemption applies.
Related provisions (quick list)
- § 150.2(b) — Altered residential space‑conditioning systems: refrigerant, minimum airflow, duct sealing FVDT requirements.
- § 160.2 — Dwelling‑unit ventilation requirements and whole‑dwelling FVDT (RA3.7.4).
- § 160.3 — System airflow, static pressure probe, fan efficacy, and FVDT for forced‑air systems.
- § 150.1(c) / § 150.0(m) — New system requirements for refrigerant charge and airflow that reference RA3 procedures. file
- Reference Residential Appendices: RA3.2 (charge verification), RA3.3 (airflow & fan efficacy procedures), RA3.1 (duct sealing procedures), RA3.7 (ventilation verification) — these are the procedural documents required by the above sections. file
Code references
Grounded in the retrieved California Energy Code — click a citation to read the verbatim passage:
§ 1.4.2. High relevance — show source text
K. Duct system sealing and leakage testing. When space-conditioning systems utilize forced air duct systems to supply conditioned air to an individual dwelling unit, the ducts shall be sealed, as confirmed through field verification and diagnostic testing, in accordance with all applicable procedures specified in Reference Residential Appendix RA3.1. Air handler airflow for calculation of duct leakage rate compliance targets shall be determined according to methods specified in Reference Residential Appendix RA3.1.4.2. For multifamily dwellings with the air-handling unit installed and the ducts connected directly to the air handler, regardless of duct system location: i. The total leakage of the duct system shall not exceed 12 percent of the air handler airflow as determined utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.1; or ii. The duct system leakage to outside shall not exceed 6 percent of the air handler airflow as determined utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.4.
- Exception 1 to Section 160.3(b)5K: The field verification and ECC-Provider data registry requirements of Reference Residential Appendix RA2 and RA3 are not required for multifamily dwelling units in buildings four
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habitable stories and greater. The installer shall certify that diagnostic testing was performed in accordance with the applicable procedures. Exception 2 to Section 160.3(b)5K: Multifamily dwelling units in buildings four habitable stories and greater in Climate Zones 1, 3, 5 and 7. L. System airflow rate and fan efficacy. Space-conditioning systems that utilize forced air ducts to supply cooling to an individual dwelling unit shall: i. Static pressure probe. Have a hole for the placement of a static pressure probe (HSPP), or a permanently installed static pressure probe (PSPP) in the supply plenum downstream of the air conditioning evaporator coil. The size, location and labeling of the HSPP or PSPP shall conform to the requirements specified in Reference Residential Appendix RA3.3.1.1 as confirmed by field verification and diagnostic testing; and Exception to Section 160.3(b)5Li: Systems that cannot conform to the specifications for hole location in Reference Residential Appendix Figure RA3.3-1 shall not be required to provide holes as described in Figure RA3.3-1.
ii. Single zone central forced air systems. Demonstrate, in every control mode, airflow greater than or equal to 350 cfm per ton of nominal cooling capacity through the return grilles, and an air-handling unit fan efficacy less than or equal to the maximum W/cfm specified in Subsection a or b below. The airflow rate and fan efficacy requirements in this section shall be confirmed by field verification and diagnostic testing in accordance with the procedures given in Reference Residential Appendix RA3.3. a. 0.45 W/cfm for gas furnace air-handling units. b. 0.58 W/cfm for air-handling units that are not gas furnaces. Exception 1 to Section 160.3(b)5Lii: Standard ducted systems without zoning dampers may comply by meeting the applicable requirements in Table 160.3-A or 160.3-B as confirmed by field verification and diagnostic testing in accordance with the procedures in Reference Residential Appendix Sections RA3.1.4.4 and RA3.1.4.5.
§ 170.2 High relevance — show source text
Exception 2 to Section 170.2(c)3Bi: The field verification and ECC-Provider data registry requirements of Reference Residential Appendix RA2 and RA3 are not required for multifamily dwelling units in buildings four habitable stories and greater. The installer shall certify that diagnostic testing was performed in accordance with the applicable procedures. ii. Space-conditioning distribution systems. All space-conditioning systems shall meet all applicable requirements of a or b below:
a. High performance attics. Air handlers or ducts are allowed to be in ventilated attic spaces when the roof and ceiling insulation level meet Option B in Table 170.2-A. b. Duct and air handlers located in conditioned space. Duct systems and air handlers of HVAC systems shall be located in conditioned space, and confirmed by field verification and diagnostic testing to meet the criterion of Reference Residential Appendix RA3.1.4.3.8. NOTE: Gas heating appliances installed in conditioned spaces must meet the combustion air requirements of California Mechanical Code Chapter 7, as applicable. iii. Central fan integrated ventilation systems—systems serving individual dwelling units. Central forced air system fans used to provide outside air shall have an air-handling unit fan efficacy less than or equal to the maximum W/cfm specified in a or b below. The airflow rate and fan efficacy requirements in this section shall be confirmed through field verification and diagnostic testing in accordance with all applicable procedures specified in Reference Residential Appendix RA3.3. Central Fan Integrated Ventilation Systems shall be certified to the Energy Commission as Intermittent Ventilation Systems as specified in Reference Residential Appendix RA3.7.4.2.
a. 0.45 W/cfm for gas furnace air-handling units; or b. 0.58 W/cfm for air-handling units that are not gas furnaces. iv. Balanced ventilation systems with heat/energy recovery in Climate Zones 1, 2, 4, 11–14, and 16. A balanced ventilation system with heat or energy recovery shall be used to meet Section 160.2(b)2Aivb1, and shall meet the applicable requirements of Item a or b below: a. In Climate Zones 1, 2, 4, 11–14, and 16, balanced ventilation systems serving individual dwelling units shall:
- Be an energy recovery ventilator (ERV) or heat recovery ventilator (HRV),
- Have a minimum sensible recovery efficiency of 67 percent, rated at 32 degrees Fahrenheit (0 degrees Celsius), and
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- Have a fan efficacy less than or equal to 0.6 W per cfm. These measures shall be confirmed through field verification in accordance with the procedures in RA3.7.4.4 for buildings with three habitable stories or fewer, or the procedures in NA2.2.4.1.5 for buildings with four or more habitable stories.
b. In Climate Zones 1, 2, 4, 11–14, and 16, balanced ventilation systems serving multiple dwelling units in buildings with four or more habitable stories shall:
- Be an ERV or HRV,
§ 6.9 High relevance — show source text
B. A single 240 volt HPWH that meets the requirements of NEEA Advanced Water Heater Specification Tier 3 or higher. In addition, for Climate Zone 16, a drain water heat recovery system that is field verified as specified in Reference Appendix RA3.6.9 and the storage tank shall be located in the garage or conditioned space. C. A solar water-heating system with electric backup meeting the installation criteria specified in Reference Residential Appendix RA4 and with a minimum annual solar savings fraction of 0.7. Exception 1 to Section 150.1(c)8: An electric water heater with point of use distribution as specified in RA4.4.5 may be installed for new dwelling units with a conditioned floor area of 500 square feet or less. Exception 2 to Section 150.1(c)8A and B: A 120V HPWH may be installed in place of a 240V HPWH for new dwelling unit with one bedroom or fewer.
- Space-conditioning distribution systems. All space-conditioning systems shall meet all applicable requirements of A or B below:
A. High performance attics. Air handlers or ducts are allowed to be in ventilated attic spaces when the roof and ceiling insulation level meet Option B in Table 150.1-A. Duct insulation levels shall meet the requirements in Table 150.1-A. B. Duct systems and air handlers of HVAC systems shall be located entirely in conditioned space and confirmed through field verification and diagnostic testing to meet the criterion of Reference Residential Appendix Section RA3.1.4.3.8. Duct insulation levels shall meet the requirements in Table 150.1-A. For dwelling units with attics, the duct system and air handlers of HVAC systems shall be located below the ceiling separating the occupiable space from the attic. Note: Gas heating appliances installed in conditioned spaces must meet the combustion air requirements of the California Mechanical Code Chapter 7, as applicable. 10. Central fan integrated ventilation systems. Central forced air system fans used to provide outside air shall have an airhandling unit fan efficacy less than or equal to the maximum W/cfm specified in A, B or C. The airflow rate and fan efficacy requirements in this section shall be confirmed through field verification and diagnostic testing in accordance with all applicable procedures specified in Reference Residential Appendix RA3.3. Central fan integrated ventilation systems shall be certified to the Energy Commission as intermittent ventilation systems as specified in Reference Residential Appendix RA3.7.4.2.
A. 0.45 W/cfm for gas furnace air-handling units. B. 0.58 W/cfm for air-handling units that are not gas furnaces. C. 0.62 W/cfm for small-duct high-velocity air-handling units. Exception to Section 150.1(c)10A: Gas furnace air-handling units manufactured prior to July 3, 2019 shall comply with a fan efficacy value less than or equal to 0.58 w/cfm as confirmed by field verification and diagnostic testing in accordance with the procedures given in Reference Residential Appendix RA3.3. 11. Roofing products. All roofing products shall meet the requirements of Section 110.8 and the applicable requirements of Subsection A or B:
§ 0.45 High relevance — show source text
a. 0.45 W/cfm for gas furnace air-handling units; or b. 0.58 W/cfm for air-handling units that are not gas furnaces. iv. Balanced ventilation systems with heat/energy recovery in Climate Zones 1, 2, 4, 11–14, and 16. A balanced ventilation system with heat or energy recovery shall be used to meet Section 160.2(b)2Aivb1, and shall meet the applicable requirements of Item a or b below: a. In Climate Zones 1, 2, 4, 11–14, and 16, balanced ventilation systems serving individual dwelling units shall:
- Be an energy recovery ventilator (ERV) or heat recovery ventilator (HRV),
- Have a minimum sensible recovery efficiency of 67 percent, rated at 32 degrees Fahrenheit (0 degrees Celsius), and
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- Have a fan efficacy less than or equal to 0.6 W per cfm. These measures shall be confirmed through field verification in accordance with the procedures in RA3.7.4.4 for buildings with three habitable stories or fewer, or the procedures in NA2.2.4.1.5 for buildings with four or more habitable stories.
b. In Climate Zones 1, 2, 4, 11–14, and 16, balanced ventilation systems serving multiple dwelling units in buildings with four or more habitable stories shall:
Be an ERV or HRV,
Have a minimum sensible recovery efficiency or effectiveness of 67 percent, rated at 32 degrees Fahrenheit (0 degrees Celsius),
Meet the fan power requirements of Section 170.2(c)4A, and
Have recovery bypass or control to directly economize with ventilation air based on outdoor air temperature limits specified in Table 170.2-G.
These measures shall be field verified in accordance with NA7.18.4.
v. In buildings with three habitable stories or fewer in Climate Zones 5–10 and Climate Zone 15, when a heat pump space-conditioning system is installed to meet the requirements of Section 170.2(c)3Ai, balanced ventilation systems without an ERV or HRV shall have a fan efficacy less than or equal to 0.4 W/cfm. vi. Dwelling unit ventilation system requirements. All HRV/ERV systems serving individual dwelling units shall have a fault indicator display (FID) that is manufacturer certified in compliance with the requirements in Joint Appendix JA17.4. The FID certification shall be verified by an ECC-Rater. Exception to Section 170.2(c)3B: The field verification and ECC-Provider data registry requirements of Reference Residential Appendix RA2 and RA3 are not required for multifamily dwelling units in buildings four habitable stories and greater. The installer shall certify that diagnostic testing was performed in accordance with the applicable procedures. C. HVAC system bypass ducts. Bypass ducts that deliver conditioned supply air directly to the space-conditioning system return duct airflow shall not be used. 4. Common use area space-conditioning systems. A building complies with this section by being designed with and having constructed and installed a space-conditioning system that meets the applicable requirements of Subsections A through O. A. Fan systems.
§ 160.3 High relevance — show source text
Exception 1 to Section 160.3(b)5Liii: Multispeed or variable speed compressor systems, with controls that vary fan speed subject to the number of zones, as certified by the installer may demonstrate compliance with the airflow (cfm/ton) and fan efficacy (watt/cfm) requirements of Section 160.3(b)5Liii by operating the system at maximum compressor capacity and system fan speed with all zones calling for conditioning. Exception 2 to Section 160.3(b)5Liii: Gas furnace air-handling units manufactured prior to July 3, 2019 shall comply with a fan efficacy value less than or equal to 0.58 w/cfm as confirmed by field verification and diagnostic testing in accordance with the procedures given in Reference Residential Appendix RA3.3. iv. Small duct high velocity forced air systems. Demonstrate, in every control mode, airflow greater than or equal to 250 cfm per ton of nominal cooling capacity through the return grilles, and an air-handling unit fan efficacy less than or equal to 0.62 W/cfm as confirmed by field verification and diagnostic testing in accordance with the procedures given in Reference Residential Appendix RA3.3. Exception 1 to Section 160.3(b)5Liv: Standard ducted systems without zoning dampers may comply by meeting the applicable requirements in Table 160.3-A or 160.3-B as confirmed by field verification and diagnostic testing in accordance with the procedures in Reference Residential Appendix Sections RA3.1.4.4 and RA3.1.4.5. The design clean-filter pressure drop requirements specified by Section 160.2(b)1Div for the system air filter(s) shall conform to the requirements given in Table 160.3-A or 160.3-B. Exception 2 to Section 160.3(b)5Liv: Multispeed compressor systems or variable speed compressor systems shall verify airflow (cfm/ton) and fan efficacy (watt/cfm) for system operation at the maximum compressor speed and the maximum air handler fan speed.
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Exception 1 to Section 160.3(b)5L: The field verification and ECC-Provider data registry requirements of Reference Residential Appendix RA2 and RA3 are not required for multifamily dwelling units in buildings four habitable stories and greater. The installer shall certify that diagnostic testing was performed in accordance with the applicable procedures. Exception 2 to Section 160.3(b)5L: Multifamily dwelling units in buildings four habitable stories and greater in Climate Zone 1.
Piping for space-conditioning systems, solar water-heating system collector loop, and distribution piping for steam and hydronic heating system shall meet the requirements of Section 160.3(c)1.
Defrost .
A. If a heat pump is equipped with a defrost delay timer, the delay timer must be set to greater than or equal to 90 minutes.
B. The installer shall certify on the Certificate of Installation that the control configuration has been tested in accordance with the testing procedure found in the Certificate of Installation. Exception to 160.3(b)7 . Dwelling units in Climate Zones 1, 6 through 10, 15, and 16 shall not be required to comply with the 90-minute delay timer requirements. 8. **Capacity variation with third-party thermostats.
§ 2.3.2 High relevance — show source text
If the verification procedure in Section RA3.2.3.2 is used for compliance, the system’s thermostat shall conform to the specifications in Section 110.12. Ducted systems shall comply with the minimum system airflow rate requirement in Section 170.2(c)3BiaII.
b. For air-cooled air conditioners and air-source heat pumps, including but not limited to ducted split systems, ducted packaged systems, small duct high velocity systems and mini-split systems, which are of a type that cannot comply with the requirements of Section 170.2(c)3Bi: I. The installer shall confirm the refrigerant charge using the weigh-in charging procedure specified in Reference Residential Appendix Section RA3.2.3.1, as verified by a ECC-Rater according to the procedures specified in Reference Residential Appendix Section RA3.2.3.2; and II. Systems that utilize forced air ducts shall comply with the minimum system airflow rate requirement in Section 170.2(c)3BiaII, provided the system is of a type that can be verified using the procedures in RA3.3 or an approved alternative procedure in RA1. Exception 1 to Section 170.2(c)3Bi: Packaged systems for which the manufacturer has verified correct system refrigerant charge prior to shipment from the factory are not required to have refrigerant charge confirmed through field verification and diagnostic testing. The installer of these packaged systems shall certify that the packaged system was precharged at the factory and has not been altered in a way that would affect the charge. Ducted systems shall comply with minimum system airflow rate requirement in Section 170.2(c)3Bib, provided that the system is of a type that can be verified using the procedure specified in RA3.3 or an approved alternative in RA1. Exception 2 to Section 170.2(c)3Bi: The field verification and ECC-Provider data registry requirements of Reference Residential Appendix RA2 and RA3 are not required for multifamily dwelling units in buildings four habitable stories and greater. The installer shall certify that diagnostic testing was performed in accordance with the applicable procedures. ii. Space-conditioning distribution systems. All space-conditioning systems shall meet all applicable requirements of a or b below:
a. High performance attics. Air handlers or ducts are allowed to be in ventilated attic spaces when the roof and ceiling insulation level meet Option B in Table 170.2-A. b. Duct and air handlers located in conditioned space. Duct systems and air handlers of HVAC systems shall be located in conditioned space, and confirmed by field verification and diagnostic testing to meet the criterion of Reference Residential Appendix RA3.1.4.3.8. NOTE: Gas heating appliances installed in conditioned spaces must meet the combustion air requirements of California Mechanical Code Chapter 7, as applicable. iii. Central fan integrated ventilation systems—systems serving individual dwelling units. Central forced air system fans used to provide outside air shall have an air-handling unit fan efficacy less than or equal to the maximum W/cfm specified in a or b below. The airflow rate and fan efficacy requirements in this section shall be confirmed through field verification and diagnostic testing in accordance with all applicable procedures specified in Reference Residential Appendix RA3.3. Central Fan Integrated Ventilation Systems shall be certified to the Energy Commission as Intermittent Ventilation Systems as specified in Reference Residential Appendix RA3.7.4.2.
§ 2.2 High relevance — show source text
The ECC-Rater shall verify the charge using Sections RA3.2.2 and RA3.3 or approved alternatives in Section RA1. Exception 1 to Section 150.1(c)7Aic: When the outdoor temperature is less than 55°F and the installer utilizes the weigh-in charging procedure in Reference Residential Appendix Section RA3.2.3.1 to verify the refrigerant charge, the installer may elect to utilize the verification procedure in Reference Residential Appendix Section RA3.2.3.2. If the verification procedure in Section RA3.2.3.2 is used for compliance, the system's thermostat shall conform to the specifications in Section 110.12. Ducted systems shall comply with minimum system airflow rate requirement in Section 150.1(c)7Aib. ii. Air-cooled air conditioners and air-source heat pumps, including but not limited to ducted split systems, ducted packaged systems, small duct high-velocity systems and mini-split systems, which are of a type that cannot be verified using the specified procedures, with the requirements of Section 150.1(c)7Ai shall comply with Subsections a and b, as applicable. a. The installer shall confirm the refrigerant charge using the weigh-in charging procedure specified in Reference Residential Appendix Section RA3.2.3.1, as verified by an ECC-Rater according to the procedures specified in Reference Residential Appendix Section RA3.2.3.2.; and b. Systems that utilize forced air ducts shall comply with the minimum system airflow rate requirement in Section 150.1(c)7Aib provided the system is of a type that can be verified using the procedures in Section RA3.3 or an approved alternative procedure in Section RA1.
Exception 1 to Section 150.1(c)7A: Packaged systems for which the manufacturer has verified correct system refrigerant charge prior to shipment from the factory are not required to have refrigerant charge confirmed through field verification and diagnostic testing. The installer of these packaged systems shall certify on the Certificate of Installation that the packaged system was pre-charged at the factory and has not been altered in a way that would affect the charge. Ducted systems shall comply with minimum system airflow rate requirements in Section 150.1(c)7Aib, provided that the system is of a type that can be verified using the procedure specified in Section RA3.3 or an approved alternative in Section RA1.
- Domestic water-heating systems. Water-heating systems shall meet the requirements of A, B or C, or shall meet the performance compliance requirements of Section 150.1(b)1. For recirculation distribution systems, only demand recirculation systems with manual on/off control as specified in the Reference Appendix RA4.4.9 shall be used: A. A single 240 volt heat pump water heater (HPWH). The storage tank shall be located in the garage or conditioned space. In addition, meet the following: i. A compact hot water distribution system that is field verified as specified in the Reference Appendix RA4.4.6 in Climate Zones 1 and 16; and
ii. A drain water heat recovery system that is field verified as specified in the Reference Appendix RA3.6.9 in Climate Zone 16.
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§ 150.1 High relevance — show source text
Exception to Section 150.1(c)7Aib: Standard ducted systems without zoning dampers may comply with the minimum airflow rate by meeting the applicable requirements in Table 150.0-B or 150.0-C as confirmed by field verification and diagnostic testing in accordance with the procedures in Reference Residential Appendix Section RA3.1.4.4 and RA3.1.4.5. The design clean-filter pressure drop requirements of Section 150.0(m)12D for the system air filter device(s) shall conform to the requirements given in Tables 150.0-B and 150.0-C.
c. The installer shall charge the system according to manufacturer’s specifications. Refrigerant charge shall be verified according to one of the following options, as applicable: I. The installer and rater shall perform the standard charge procedure as specified by Reference Residential Appendix Section RA3.2.2, or an approved alternative procedure as specified by Section RA1; or
II. The installer shall perform the weigh-in charging procedure as specified by Reference Residential Appendix Section RA3.2.3.1 provided the system is of a type that can be verified using the Section RA3.2.2 standard charge verification procedure and Section RA3.3 airflow rate verification procedure or approved alternatives in Section RA1. The ECC-Rater shall verify the charge using Sections RA3.2.2 and RA3.3 or approved alternatives in Section RA1. Exception 1 to Section 150.1(c)7Aic: When the outdoor temperature is less than 55°F and the installer utilizes the weigh-in charging procedure in Reference Residential Appendix Section RA3.2.3.1 to verify the refrigerant charge, the installer may elect to utilize the verification procedure in Reference Residential Appendix Section RA3.2.3.2. If the verification procedure in Section RA3.2.3.2 is used for compliance, the system's thermostat shall conform to the specifications in Section 110.12. Ducted systems shall comply with minimum system airflow rate requirement in Section 150.1(c)7Aib. ii. Air-cooled air conditioners and air-source heat pumps, including but not limited to ducted split systems, ducted packaged systems, small duct high-velocity systems and mini-split systems, which are of a type that cannot be verified using the specified procedures, with the requirements of Section 150.1(c)7Ai shall comply with Subsections a and b, as applicable. a. The installer shall confirm the refrigerant charge using the weigh-in charging procedure specified in Reference Residential Appendix Section RA3.2.3.1, as verified by an ECC-Rater according to the procedures specified in Reference Residential Appendix Section RA3.2.3.2.; and b. Systems that utilize forced air ducts shall comply with the minimum system airflow rate requirement in Section 150.1(c)7Aib provided the system is of a type that can be verified using the procedures in Section RA3.3 or an approved alternative procedure in Section RA1.
§ 110.2 High relevance — show source text
F. Altered space-conditioning system—mechanical cooling. When a space-conditioning system is an air conditioner or heat pump that is altered by the installation or replacement of refrigerant-containing system components such as the compressor, condensing coil, evaporator coil, refrigerant metering device or refrigerant piping, the altered system shall comply with the following requirements: i. All thermostats associated with the system shall be replaced with setback thermostats meeting the requirements of Section 110.2(c).
ii. Air-cooled air conditioners in Climate Zones 2 and 8 through 15 and air-source heat pumps in all climate zones, including but not limited to ducted split systems, ducted package systems, small duct high-velocity air systems, and minisplit systems shall comply with Subsections a and b, unless the system is of a type that cannot be verified using the specified procedures. Systems that cannot comply with the requirements of Section 150.2(b)1Fii shall comply with Section 150.2(b)1Fiii. Exception to Section 150.2(b)1Fii: Entirely new or complete replacement packaged systems for which the manufacturer has verified correct system refrigerant charge prior to shipment from the factory are not required to have refrigerant charge confirmed through field verification and diagnostic testing. The installer of these packaged systems shall certify on the Certificate of Installation that the packaged
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system was pre-charged at the factory and has not been altered in a way that would affect the charge. Ducted systems shall comply with minimum system airflow rate requirement in Section 150.2(b)1Fiia, provided that the system is of a type that can be verified using the procedure specified in RA3.3 or an approved alternative in RA1. a. Minimum system airflow rate shall comply with the applicable Subsection I or II below as confirmed through field verification and diagnostic testing in accordance with the procedures specified in Reference Residential Appendix Section RA3.3 or an approved alternative procedure as specified in Section RA1.
- Small duct high-velocity systems shall demonstrate a minimum system airflow rate greater than or equal to 250 cfm per ton of nominal cooling capacity; or
- All other air-cooled air conditioner or air-source heat pump systems shall demonstrate a minimum system airflow rate greater than or equal to 300 cfm per ton of nominal cooling capacity; and Exception 1 to Section 150.2(b)1Fiia: Systems unable to comply with the minimum airflow rate requirement shall demonstrate compliance using the procedures in Section RA3.3.3.1.5; and the system’s thermostat shall conform to the specifications in Section 110.12. Exception 2 to Section 150.2(b)1Fiia: Entirely new or complete replacement space-conditioning systems, as specified by Section 150.2(b)1C, without zoning dampers may comply with the minimum airflow rate by meeting the applicable requirements in Table 150.0-B or 150.0-C as confirmed by field verification and diagnostic testing in accordance with the procedures in Reference Residential Appendix Section RA3.1.4.4 and RA3.1.4.5. The design clean-filter pressure drop requirements of Section 150.0(m)12C for the system air filter device(s) shall conform to the requirements given in Tables 150.0-B and 150.0-C.
§ 160.2 High relevance — show source text
Exception to Section 160.2(b)2Axia: Systems that require servicing from inside the attic shall have the following:
- A fault indicator display (FID) meeting the requirements of Reference Appendix JA 17; and
- An attic access door located in a wall or, where attic access is provided through a ceiling, an attic access hatch that includes an integrated ladder; and
- A walkway from the attic access door to the HRV/ERV. b. IAQ system component accessibility. Fans, motors, heat exchangers, filters and recovery cores shall meet all applicable requirements of California Mechanical Code Section 304.0 accessibility of service. B . Dwelling unit field verification and diagnostic testing. i. Whole-dwelling unit ventilation airflow performance . The whole-dwelling unit ventilation airflow required by Section 160.2(b)2Aiv or 160.2(b)2Av shall be confirmed through field verification and diagnostic testing in accordance with Reference Appendix RA3.7.4.1.1 or NA2.2.4.1.1 as applicable for supply and exhaust systems or RA3.7.4.1.2 or NA2.2.4.1.2 as applicable for balanced systems. Balanced mechanical ventilation system airflow shall be the average of the supply fan and exhaust fan flows. Ventilation airflow of systems with multiple operating modes shall be tested in all modes designed to comply with the required ventilation airflows. ii. Kitchen local mechanical exhaust—vented range hoods. Vented range hoods installed to comply with local mechanical exhaust requirements specified in Section 160.2(b)2Avi shall be field verified in accordance with
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Reference Appendix RA3.7.4.3 or NA2.2.4.1.4 as applicable to confirm the model is rated by HVI or AHAM to comply with the following requirements: a. The minimum ventilation airflow rate as specified by Section 160.2(b)2Avi, or alternatively the minimum capture efficiency as specified by Section 160.2(b)2Avi; and b. The maximum sound rating as specified in Section 160.2(b)2Avif. iii. Heat recovery ventilation (HRV) and energy recovery ventilation (ERV) system fan efficacy. At a minimum, systems with heat or energy recovery serving a single dwelling unit shall have a fan efficacy of ≤1.0 W/cfm as confirmed by field verification in accordance with Reference Appendix RA3.7.4.4 or NA2.2.4.1.5 as applicable. If Section 170.2(c)3Biva requirements are applicable to the dwelling unit, then field verification shall instead confirm compliance with the maximum fan efficacy and minimum sensible recovery efficiency specified in Section 170.2(c)3Biva in accordance with the procedures specified in Reference Appendix RA3.7.4.4 or NA2.2.4.1.5 as applicable. iv. In multifamily buildings with four or more habitable stories, the field verification and diagnostic testing required in Sections 160.2(b)2Bi, ii and iii which requires an ECC-Rater may alternatively be performed by a certified Mechanical Acceptance Test Technician according to the requirements specified in Reference Appendix NA1.9. C. Multifamily building central ventilation system field verification. i. **Central ventilation system duct sealing.
§ 2.2 High relevance — show source text
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the RA3.2.2 standard charge verification procedure and RA3.3 airflow rate verification procedure or approved alternatives in RA1. The ECC-Rater shall verify the charge using RA3.2.2 and RA3.3 or approved alternatives in RA1. Exception to Section 170.2(c)3BiaI: Systems that cannot conform to the specifications for hole location in Reference Residential Appendix Figure RA3.2-1 shall not be required to provide holes as described in Figure RA3.2-1. Exception to Section 170.2(c)3BiaII: Standard ducted systems without zoning dampers may comply with the minimum airflow rate by meeting the applicable requirements in Table 160.3-A and Table 160.3-B as confirmed by field verification and diagnostic testing in accordance with the procedures in Reference Residential Appendix Sections RA3.1.4.4 and RA3.1.4.5. The design clean-filter pressure drop requirements of Section 160.2(b)1D for the system air filter device(s) shall conform to the requirements given in Table 160.3-A and Table 160.3-B. Exception to Section 170.2(c)3BiaIII : When the outdoor temperature is less than 55°F and the installer utilizes the weigh-in charging procedure in Reference Residential Appendix Section RA3.2.3.1 to verify the refrigerant charge, the installer may elect to utilize the verification procedure in Reference Residential Appendix Section RA3.2.3.2. If the verification procedure in Section RA3.2.3.2 is used for compliance, the system’s thermostat shall conform to the specifications in Section 110.12. Ducted systems shall comply with the minimum system airflow rate requirement in Section 170.2(c)3BiaII.
b. For air-cooled air conditioners and air-source heat pumps, including but not limited to ducted split systems, ducted packaged systems, small duct high velocity systems and mini-split systems, which are of a type that cannot comply with the requirements of Section 170.2(c)3Bi: I. The installer shall confirm the refrigerant charge using the weigh-in charging procedure specified in Reference Residential Appendix Section RA3.2.3.1, as verified by a ECC-Rater according to the procedures specified in Reference Residential Appendix Section RA3.2.3.2; and II. Systems that utilize forced air ducts shall comply with the minimum system airflow rate requirement in Section 170.2(c)3BiaII, provided the system is of a type that can be verified using the procedures in RA3.3 or an approved alternative procedure in RA1. Exception 1 to Section 170.2(c)3Bi: Packaged systems for which the manufacturer has verified correct system refrigerant charge prior to shipment from the factory are not required to have refrigerant charge confirmed through field verification and diagnostic testing. The installer of these packaged systems shall certify that the packaged system was precharged at the factory and has not been altered in a way that would affect the charge. Ducted systems shall comply with minimum system airflow rate requirement in Section 170.2(c)3Bib, provided that the system is of a type that can be verified using the procedure specified in RA3.3 or an approved alternative in RA1.
§ 180.2 High relevance — show source text
b. In Climate Zones 2 and 8 through 15, air-cooled air conditioners and air-source heat pumps, including but not limited to ducted split systems, ducted package systems, small duct high velocity air systems, and minisplit systems, shall comply with Subsections I and II, unless the system is of a type that cannot be verified using the specified procedures. Systems that cannot comply with the requirements of Section 180.2(b)2Aivb shall comply with Section 180.2(b)2Aivc. Exception to Section 180.2(b)2Aivb: Entirely new or complete replacement packaged systems for which the manufacturer has verified correct system refrigerant charge prior to shipment from the factory are not required to have refrigerant charge confirmed through field verification and diagnostic testing. The installer of these packaged systems shall certify that the packaged system was pre-charged at the factory and has not been altered in a way that would affect the charge. Ducted systems shall comply with the minimum system airflow rate requirement in Section 180.2(b)2AivbI, provided that the system is of a type that can be verified using the procedure specified in RA3.3 or an approved alternative in RA1. I. The minimum system airflow rate shall comply with the applicable Subsection A or B below as confirmed through field verification and diagnostic testing in accordance with the procedures specified in Reference Residential Appendix Section RA3.3 or an approved alternative procedure as specified in Section RA1. A. Small duct high velocity systems shall demonstrate a minimum system airflow rate greater than or equal to 250 cfm per ton of nominal cooling capacity; or
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B. All other air-cooled air conditioner or air-source heat pump systems shall demonstrate a minimum system airflow rate greater than or equal to 300 cfm per ton of nominal cooling capacity. Exception 1 to Section 180.2(b)2AivbI : Systems unable to comply with the minimum airflow rate requirement shall demonstrate compliance using the procedures in Section RA3.3.3.1.5, and the system's thermostat shall conform to the specifications in Section 110.12. Exception 2 to Section 180.2(b)2AivbI: Entirely new or complete replacement space-conditioning systems, as specified by Section 180.2(b)2Ai, without zoning dampers may comply with the minimum airflow rate by meeting the applicable requirements in Table 160.3-A or 160.3-B as confirmed by field verification and diagnostic testing in accordance with the procedures in Reference Residential Appendix Sections RA3.1.4.4 and RA3.1.4.5. The design clean-filter pressure drop requirements of Section 160.2(a)1C for the system air filter device(s) shall conform to the requirements given in Tables 160.3-A and 160.3-B.
II. The installer shall charge the system according to manufacturer’s specifications. Refrigerant charge shall be verified according to one of the following options, as applicable.
Frequently asked questions
When exactly does § 150.2(b) require FVDT?
Whenever a space‑conditioning system is altered by replacement/installation of refrigerant‑containing components or when altered ducts exceed the Code’s thresholds (e.g., >25 ft of new ducts), FVDT is required to confirm refrigerant charge, minimum airflow and duct sealing per § 150.2(b) and the RA procedures. file
Do I always need an ECC‑Rater to verify refrigerant weigh‑in?
If the RA procedure requires ECC‑Rater verification (RA3.2.3.2) then yes — the ECC‑Rater verifies the installer’s weigh‑in per the RA procedure. Packaged units precharged by the manufacturer and certified as unaltered are an exception. file
Which airflow number applies — 250, 300 or 350 cfm/ton?
Use the threshold that matches the Code context: 250 cfm/ton for small‑duct high‑velocity systems; 300 cfm/ton for altered air‑cooled/air‑source systems per § 150.2(b); 350 cfm/ton for many new single‑zone central forced‑air systems — check the specific subsection you are working under. file
How is whole‑dwelling ventilation verified?
Whole‑dwelling ventilation airflow is confirmed by FVDT using RA3.7.4 (or NA2.2.4 procedures), testing supply and exhaust (balanced systems use the average), and testing all operating modes used for compliance.
If a system can’t physically accept a static probe hole, what then?
The Code exempts systems that cannot conform to the prescribed hole locations; other verification methods or approved alternatives in the RA/RA1 procedures apply.
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