1715.7 System Start-Up — 2025 California Mechanical Code

California Mechanical Code (Title 24, Part 4) · 2025 edition · updated 2026-09-25 · California

CBSC: official editions, supplements and errata

Italicized text is a California amendment to the model code, as printed in the official publication.

Cite as: 2025 California Mechanical Code (Title 24, Part 4) § 1715.7 · Effective January 1, 2026 · Official source: Building Standards Commission

DX system start-up shall be in accordance with Section 1708.1 and the following:

(1) DX systems shall be pressurized using nitrogen for not less than 1 hour. There shall be no allowable variance to

the test pressure after being corrected for ambient temperature changes during the test. The test pressure shall not exceed 150 psig (1034 kPa) when pressure testing the compressor unit and indoor system components.

(2) DX systems shall have permanent type labels installed and affixed on the compressor unit with the refrigerant type and quantity.

(3) For DX systems, refrigerant liquid and vapor lines from the loop system shall be identified and tagged.

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▸Contents — California Mechanical Code (Title 24, Part 4)

California Mechanical Code (Title 24, Part 4)

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