Mini-Split Installation Title 24 Checklist
A ductless mini-split skips the duct test, duct insulation and airflow check, but not the rest. A heat pump unit needs a verified refrigerant charge in every climate zone, a cooling-only unit in zones 2 and 8 to 15. Some units cannot take the standard test, so the installer weighs in the charge while an ECC-Rater observes.
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What drops out and what stays
The Energy Commission lists duct leakage and fan efficacy as ducted-system checks, and Section 150.2(b)1Fiiib attaches the airflow minimum to forced-air duct systems. The charge rule, though, names minisplit systems outright (Section 150.2(b)1Fii). Where an indoor unit feeds ductwork, the ducted-system checks apply to that part of the job.
The weigh-in, step by step
- The installer picks a route. With a new factory-charged outdoor unit, only the line set and indoor coil adjustment is weighed in, after those parts are evacuated. Otherwise the whole system is recovered, evacuated and charged by total weight.
- Where the manufacturer calls for a vacuum leak check, the system reaches 500 microns or less and rises no more than 300 microns over five minutes. Where it specifies a nitrogen pressure test instead, the system holds the stated pressure.
- The scale reads within 0.5 ounce or 0.5 percent. The line set length and diameter, the coil adjustment, and the calculated and actual weights are written at the nameplate in permanent ink.
- The ECC-Rater watches the process and may not add or remove refrigerant. No sampling is allowed, and weigh-in works at any outdoor temperature.
Site and control items
- The outdoor unit sits at least 5 feet from any dryer vent outlet, and a liquid line drier goes in if the manufacturer calls for one (Section 150.0(h)3).
- Thermostats on the altered system become setback controls with at least four programmable periods in 24 hours (Sections 150.2(b)1Fi and 110.2(c)). Ask the plan checker how a wireless remote is read.
- Ductless systems are excepted from the capacity caps that apply to additions, and a typical split unit under 45,000 Btu/h is certified at 14.3 SEER2 or better.
Permit and paperwork
Whether a permit is needed is the building department's decision. The documents are CF1R-ALT-02-E and the charge forms CF2R-MCH-25-H and CF3R-MCH-25-H. Compare the heat pump checklist, the ADU mini-split page and charge verification. Cooling a house with no ducts is on adding central air, and reports start at residential.
Common Title 24 Questions
- When is Title 24 required for a home?
- Does a remodel need Title 24?
- Does a room addition need Title 24?
- What plans are needed for a residential Title 24 report?
- How much does a residential Title 24 report cost?
- How long does a residential Title 24 report take?
Frequently Asked Questions
No. The compliance manual says only an EPA-certified technician adds or removes refrigerant. The rater observes the weigh-in or runs the test, then records the result.
Section 150.0(h)1 sets how loads are calculated, and the manual lists it for entirely new systems. Ask the building department whether a single-room unit needs one on your permit.
Explore Mini-Splits
- Refrigerant Line Set Insulation on an AC or Mini-Split: What the Code Requires
- Replacing Ducted Central Air With Mini-Splits: What Title 24 Asks
- Cooling-Only Mini-Split or Heat Pump Mini-Split: What Triggers More?
- Home Addition With a Mini-Split: Title 24 Design Guide
- How Many Heads Can a Mini-Split Have, and Does Adding One Trigger Title 24?
View all Mini-Splits guides → · HVAC and Water Heating · Title 24 guide