Chapter 17 — GEOTHERMAL ENERGY SYSTEMS AND AMBIENT TEMPERATURE LOOPS
1713.3 Design Considerations. A groundwater heat
California Mechanical Code (Title 24, Part 4) · 2025 edition · updated 2026-09-10 · California
Italicized text is a California amendment to the model code, as printed in the official publication.
pump system shall be designed by a registered design professional. Due design consideration shall be given to the following:
(1) Where multiple heat pumps or fan coils are connected to a common water loop, a diversified building design load shall be used to design a ground water heat pump.
(2) The water supply well(s) and injection wells, or water discharge system, shall be capable of being operated at sustainable pumping rates that exceed the maximum daily requirements without causing an adverse impact to existing or future offsite uses of groundwater or surface water bodies.
(3) The water temperature and the quality and chemical composition of the water resource are in accordance with the system manufacturer’s recommendations.
(4) The groundwater and surface water resources shall be protected by returning water to the source aquifer or an aquifer with the same water quality, or a surface water body.
(5) The return capacity of the injection, or surface water body discharge system, shall be suitable under winter conditions.
(6) The temperature of the return water shall have no adverse thermal impacts on offsite existing or future uses of groundwater, or on surface water bodies, in accordance with the requirements of the Authority Having Jurisdiction.
(7) Pressure gauges shall be provided to aid in start-up and monitoring of the system during operation.
(8) The ability to switch over operation of supply and return wells for 100 percent standby, redevelopment, cleaning of wells, and the thermal balancing of the ground and aquifer shall be provided.
(9) There shall be no adverse effects on the quality and quantity of offsite existing or future users of groundwater, in accordance with the requirements of the Authority Having Jurisdiction.
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Ask AI about this code▸Contents — California Mechanical Code (Title 24, Part 4)
- Chapter 1 — GENERAL CODE PROVISIONS
- Chapter 2 — DEFINITIONS
- Chapter 3 — GENERAL REGULATIONS
- Chapter 4 — VENTILATION AIR
- Chapter 5 — EXHAUST SYSTEMS
- Chapter 6 — DUCT SYSTEMS
- Chapter 7 — COMBUSTION AIR
- Chapter 8 — CHIMNEYS AND VENTS
- Chapter 9 — INSTALLATION OF SPECIFIC APPLIANCES
- Chapter 10 — BOILERS AND PRESSURE VESSELS
- Chapter 11 — REFRIGERATION
- Chapter 12 — HYDRONICS
- Chapter 13 — FUEL GAS PIPING
- Chapter 14 — PROCESS PIPING
- Chapter 15 — SOLAR ENERGY SYSTEMS
- Chapter 16 — STATIONARY POWER PLANTS
▸Chapter 17 — GEOTHERMAL ENERGY SYSTEMS AND AMBIENT TEMPERATURE…
Overview- 1701.1 Applicability. Part I of this chapter shall apply to
- 1701.2 Construction Documents. The construction doc
- 1701.3 Site Survey. A site survey shall be conducted prior
- 1701.4 Used Materials. The installation of used pipe, fittings…
- 1701.5 Contact with Building Material. A ground source
- 1701.6 Strains and Stresses. Piping shall be installed so
- 1701.7 Flood Hazard. Piping located in a flood hazard area
- 1701.8 Pipe Support. Pipe shall be supported in accordance wit…
- 1701.9 Velocities. Ground source heat pump ground-loop
- 1701.10 Chemical Compatibility. Antifreeze and other
- 1701.11 Heat Transfer Fluid. The heat transfer fluid shall
- 1702.1 General. The potable water supply connected to a
- 1703.3 Fittings. For water-based systems, fittings for
- 1703.4 Underground Piping and Submerged Materi-
- 1703.1 Ground-Heat Exchanger Design. The groundheat exchanger …
- 1703.2 Piping and Tubing Materials Standards. For
- 1703.5 Indoor Piping. Indoor piping, fittings, and accessories…
- 1704.1 Heat Pump Distribution System. The heat pump
- 1704.2 Circulating Pumps. The circulating pump shall be
- 1705.1 Where Required. Shutoff valves shall be installed
- 1705.2 Heat Exchangers. Shutoff valves shall be installed
- 1705.3 Central Systems. Shutoff valves shall be installed
- 1705.4 Pressure Vessels. Shutoff valves shall be installed
- 1705.5 Pressure-Reducing Valves. Shutoff valves shall
- 1705.6 Equipment and Appliances. Shutoff valves shall
- 1705.7 Expansion Tanks. Shutoff valves shall be installed
- 1705.8 Reduced Pressure. A pressure relief valve shall
- 1706.1 General. Heat pumps shall be in compliance with
- 1706.2 Heat Exchangers. Heat exchangers used for heat
- 1706.3 Heat-Transfer Medium. The heat-transfer medium
- 1706.4 Insulation. The temperature of surfaces within
- 1707.1 Prior to Construction. Documents for permits
- 1707.2 Equipment, Accessories, Components, and
- 1707.3 Construction Documents. The construction documents for …
- 1707.4 Site Survey Requirements. The site survey shall
- 1707.5 Subsurface Investigation. A subsurface investigation sh…
- 1707.6 Subsurface Conditions. The water well logs and
- 1707.7 Ground-Heat Exchanger Installation Prac-
- 1707.13 Steel Nail Plates. Steel nail plates shall be
- 1707.14 Exterior Piping Protection. Exterior piping shall
- 1707.15 Heat Pump and Distribution System Instal-
- 1707.16 Pressurizing During Installation. Ground
- 1707.17 Horizontal Geothermal Piping - Materials
- 1707.18 Trenches, Excavation, and Backfill. Excavation
- 1707.8 Trenching, Excavation, and Backfill. Prior to
- 1707.9 Trenches, Tunneling, and Driving. Trenches shall
- 1707.10 Excavations and Open Trenches. Excavations
- 1707.11 Protection of Piping, Materials, and Struc-
- 1707.12 Sleeves. In exterior walls, annular space between
- 1708.1 General. The following requirements shall be verified p…
- 1708.2 Operation and Maintenance Manual. An operation and main…
- 1708.3 Labeling and Marking. Ground source heat pump
- 1708.4 Documentation. The ground source heat pump system as-bu…
- 1708.5 Maintenance. The periodic maintenance required,
- 1708.6 Records. The ground source heat pump system constructio…
- 1708.7 System Start-Up. System start-up shall be in accordance…
- 1708.8 Contaminants. Particulate contaminants shall be
- 1709.1 General. Decommissioning of geothermal systems
- 1710.1 Applicability. Part II of this chapter shall apply to
- 1710.2 Piping and Tubing. Piping and tubing for closedloop sys…
- 1710.3 Borehole Piping and Tubing. Borehole piping or
- 1710.4 Underground Fittings. Underground fittings for
- 1710.5 Verification. For closed-loop systems, the system
- 1710.6 Vertical Bores. Vertical bores shall be drilled to a
- 1711.1 Testing. Pressure-testing of the ground-heat
- 1711.2 Individual Loop Pressure Testing. Individual
- 1711.3 Field Pressure Testing – Final. The ground-heat
- 1711.4 Field Flow Testing – Final. Final field flow testing
- 1712.1 Applicability. Part III of this chapter shall apply to
- 1712.2 Test Wells. Test wells drilled to investigate subsurfac…
- 1712.3 Installation of Water Wells. Water supply,
- 1712.4 Setbacks. Open-loop ground-heat exchangers shall
- 1713.1 General. The installation and use of water wells
- 1713.2 Open-Loop Water Well Drilling Logs. The water
- 1713.3 Design Considerations. A groundwater heat
- 1713.4 Water Wells and Injection Wells. Water wells
- 1713.5 Testing and Sampling. Pumping tests and water
- 1713.6 Disinfection. Water wells shall be disinfected upon
- 1714.1 Pumping Test. Water supply wells and injection
- 1714.2 Retesting. Where sediment is present, the problem
- 1714.3 Variable Rate Pump Test. The operating conditions of th…
- 1714.4 Constant Rate Pump Test. The sustainable well
- 1714.5 Water Level Monitoring. Water levels shall be
- 1714.6 Injection Wells. Injection testing shall be performed
- 1714.7 Re-Injected Water. The water quality of re-injected
- 1715.1 General. The installation and use of Direct
- 1715.2 Applicability. Part IV of this chapter shall apply to
- 1715.3 DX Systems. Copper pipe and tubing installed for
- 1715.4 DX System Testing. For direct exchange (DX) systems, ea…
- 1715.5 Indoor Piping. For DX systems, joints shall be
- 1715.6 On Site Storage. For DX systems, copper piping
- 1715.7 System Start-Up. DX system start-up shall be in
- 1715.8 DX Piping. DX Piping should be installed in accordance …
- 1716.1 General. An Ambient Temperature Loop (ATL) distributed …
- 1716.2 Permitting. Permits required for the installation and
- 1716.3 Ambient Loop Temperature Range. The operating loop temp…
- 1716.4 Shutoff Valve. An automatic shutoff valve shall be
- 1716.5 Bypass. The ATL distributed energy system shall
- 1716.6 Metering. Where meters are required by the system
- 1717.1 Thermal Resources. The ambient temperature loop
- 1717.2 District Load Profiles. The district load profile of
- Chapter 18 — REFERENCED STANDARDS
- Appendix A — RESIDENTIAL PLAN EXAMINER REVIEW FORM FOR HVAC SY…
- Appendix B — PROCEDURES TO BE FOLLOWED TO PLACE GAS EQUIPMENT …
- Appendix C — INSTALLATION AND TESTING OF OIL (LIQUID) FUEL-FIR…
- Appendix D — FUEL SUPPLY: MANUFACTURED/MOBILE HOME PARKS AND R…
- Appendix E — SUSTAINABLE PRACTICES
- Appendix F — SIZING OF VENTING SYSTEMS AND OUTDOOR COMBUSTION …
- Appendix G — EXAMPLE CALCULATION OF OUTDOOR AIR RATE
- Appendix H — PROFESSIONAL QUALIFICATIONS
- Appendix I — INDOOR HORTICULTURAL FACILITIES
- Appendix J — CLEAN AIR DELIVERY