1201.10 Freeze Protection — 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) § 1201.10 · Effective January 1, 2026 · Official source: Building Standards Commission
Hydronic systems and components shall be designed, installed, and protected from freez
ing. The percent of glycol by volume shall be determined based on the freezing point of the solution and type of mixture in accordance with Table 1201.10 or the manufacturer’s specifications.
For SI units: °C = (°F-32)/1.8 Note:
- Ethylene glycol shall not be used in one- and two-unit residential systems. In existing systems, where ethylene glycol is used, there shall be no direct or permanent potable water connections. Where a temporary potable water connection is required, a backflow preventer shall be installed.
1201.10.1 Antifreeze Requirements. Antifreeze shall be added to a closed hydronic system where one or more of the following conditions exists:
(1) System component(s) are exposed to freezing conditions.
(2) The hydronic system serves as a snow and ice melt system in accordance with Section 1220.0.
(3) Where required by the equipment manufacturer.
Exception: Antifreeze shall not be required where a system is continuously monitored or specifically designed not to require antifreeze, and is subject to freezing as a result of either of the following:
(1) Loss of electrical power.
(2) Loss of a fuel source.
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