Chapter 17 — GEOTHERMAL ENERGY SYSTEMS AND AMBIENT TEMPERATURE LOOPS
1703.2 Piping and Tubing Materials Standards — 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) § 1703.2 · Effective January 1, 2026 · Official source: Building Standards Commission
For water-based systems, ground source heat pump ground-loop pipe and tubing shall comply with the standards listed in Table 1703.2. Piping and tubing used for DX systems shall be of copper in accordance with Section 1715.3.
TABLE 1703.2
PLASTIC GROUND SOURCE LOOP PIPING
| MATERIAL | STANDARD |
|---|---|
Cross-linked Polyethylene (PEX) |
ASTM F876, CSA B137.5, ANSI/ NSF/ |
High Density Polyethylene (HDPE) |
ASTM D2737, ASTM D3035, ASTM F714, AWWA C901, CSA B137.1, ANSI/ NSF/ |
Polypropylene (PP) |
ASTM F2389, CSA B137.11, NSF/ |
Polyethylene of Raised Tempera- ture (PE-RT) |
ASTM F2623, ASTM F2769, CSA B137.18, ANSI/ NSF/ |
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GEOTHERMAL ENERGY SYSTEMS AND AMBIENT TEMPERATURE LOOPS
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turer’s installation instructions, the appropriate standards listed in accordance with Table 1703.3, and one of the following heat fusion methods:
(1) Butt-fusion joints shall be made in accordance with ASTM F2620.
(2) Socket-fusion joints shall be made in accordance with ASTM F2620.
(3) Electrofusion joints shall be made in accordance with ASTM F1055.
1703.4.2 Polyethylene of Raised Temperature (PE-RT). Polyethylene of raised temperature tubing shall be manufactured in accordance with the standards
listed in Table 1703.2. Tubing shall have a minimum wall thickness equal to SDR 9 and shall have a minimum pressure rating of not less than 160 psi (1103 kPa) at 73°F (23°C).
Polyethylene of raised temperature tubing shall be manufactured from a PE compound that has a pipe material designation code of PE 2708, PE 3608, or PE 4710 as defined in the applicable standards referenced in Table 1703.2, with a cell classification in accordance with ASTM D3350 appropriate for the material designation code.
1703.4.2.1 Joining Methods for Polyethylene of Raised Temperature (PE-RT). Joints between polyethylene of raised temperature (PE-RT) tubing and fittings shall be installed in accordance with the manufacturer’s installation instructions and the
appropriate standards listed in accordance with Table 1703.3.
1703.4.3 Cross-Linked Polyethylene (PEX). Crosslinked polyethylene pipe shall be manufactured in accordance with the standards listed in Table 1703.2. PEX
shall have a minimum tubing material designation code of PEX 1206 and shall have a minimum pressure rating of not less than 160 psi (1103 kPa) at 73°F (23°C).
1703.4.3.1 Joining Methods for Cross- Linked Polyethylene Tubing. Joints between cross-linked polyethylene (PEX) pipe or tubing and fittings shall be installed in accordance with the manufacturer’s installation instructions and the
appropriate standards in accordance with Table 1703.3.
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