Pumps, Controls, Insulation & Identification

Grounded in the retrieved California Mechanical Code — click a citation to read the verbatim passage:

• CMC § 1207.5 Medium relevance — show source text

  Heat pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1207.5

  Heat sources . . . . . . . . . . . . . . . . . . . . . . . . . . . 1203.1

  Heat transfer fluid . . . . . . . . . . . . . . . . . . 1201.3, 1204.7

  Identification of piping . . . . . . . . . . . . . . . . . . . . . 1204.0

  Installation . . . . . . . . . . . . . . . . . . . . . . . 1205.0, 1221.0

  Insulation. . . . . . . . . 1201.2, 1217.8.2, 1217.10, 1220.4.7

  Joints and connections . . . . . . . . . . . . . . . . . . . . 1211.0

  Materials . . . . . . . . . . . . . . . . . . . . 1210.0, Table 1210.1

  Protection of potable water supply . . . . . . . . . . . 1202.0

  Radiant heating and cooling . . . . . . . . . . . . . . . . 1217.0

  Snow melt systems . . . . . . . . . . . . . . . . 1220.4, 1220.0,

  1217.8.2, Table 1220.4.2

  Safety devices. . . . . . . . . . . . . . . . . . . . . . . . . . . 1206.0

  Steam systems . . . . . . . . . . . . . . . . . . . . . . . . . . 1216.0

  Testing . . . . . . . . . . . . . . . . . . . . . . . . . . 1205.2, 1221.3

  Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1212.0

  Water heaters . . . . . . . . . . . . . . . . . . . . 1203.2, 1203.3,

  1207.3, Table 1203.2

  – I –

  IDLH

  Definition,. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211.0

  Refrigeration . . . . . . . . . . . . . . . . 1106.2.5, 1106.11.10.3

  INCINERATORS

  Commercial and

  industrial type . . . . . . . . . . . . . . . . . . . . . . . . . . 924.0

  Fume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208.0, 512.3

  Residential . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 924.3

  INDOOR HORTICULTURAL FACILITIES . . . . . . Appendix I

• CMC § 501.2 Medium relevance — show source text

  L 501.2 Insulation. Hot water supply and return piping shall be thermally insulated. The wall thickness of the insulation shall be equal to the nominal diameter of the pipe up to 2 inches (50 mm). The wall thickness shall be not less than 2 inches (51 mm) for nominal pipe diameters exceeding 2 inches (50 mm). The conductivity of the insulation [k-factor (Btu•in/(h•ft [2] - °F))], measured radially, shall not be more than 0.28 [Btu•in/(h•ft [2] - °F)] [0.04 W/(m•K)]. Hot water piping to be insulated shall be installed such that insulation is continuous. Pipe insulation shall be installed to within [1] ⁄ 4 of an inch (6.4 mm) of appliances, appurtenances, fixtures, structural members, or a wall where the pipe passes through to connect to a fixture within 24 inches (610 mm).

  2025 CALIFORNIA PLUMBING CODE 507

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  APPENDIX L

  Exceptions:

  (1) Where the hot water pipe is installed in a wall that is not of a width to accommodate the pipe and insulation, the insulation thickness shall be permitted to have the maximum thickness that the wall is capable of accommodating and not less than [1] ⁄ 2 of an inch (12.7 mm) thick.

  (2) Hot water supply piping exposed under sinks, lavatories, and similar fixtures.

  L 501.2.1 Pipe Supports. Pipe supports shall be installed on the outside of the pipe insulation.

  Exception: Vertical supports, and horizontal and vertical anchors shall be installed on the pipe inside the pipe insulation.

  L 501.2.2 Building Cavities. Building cavities used for hot water supply and return piping shall be large enough to accommodate the combined diameter of the pipe plus the insulation, plus any other objects in the cavity that the piping must cross. L 501.3 Recirculation Systems. Recirculation systems shall comply with Section L 501.3.1 and Section L 501.3.2.

  L 501.3.1 For Low-Rise Residential Buildings. Circulating hot water systems shall be arranged so that the circulating pump(s) are capable of being turned off (automatically or manually) where the hot water system is not in operation. [ASHRAE 90.2-2007:7.2] L 501.3.2 For Pumps Between Boilers and Stor- age Tanks. Where used to maintain storage tank water temperature, recirculating pumps shall be equipped with controls limiting operation to a period from the start of the heating cycle to a maximum of 5 minutes after the end of the heating cycle. [ASHRAE 90.1:7.4.4.4] L 501.4 Recirculation Pump Controls. Pump controls shall include on-demand activation or time clocks combined with temperature sensing. Time clock controls for pumps shall not let the pump operate more than 15 minutes every hour. Temperature sensors shall stop circulation where the temperature set point is reached and shall be located on the circulation loop at or near the last fixture. The pump, pump controls, and temperature sensors shall be accessible. Pump operation shall be limited to the building’s hours of operation.

• CMC § 207.1.3 Medium relevance — show source text

  3. Where used to control both comfort heating and comfort cooling, the thermostatic controls shall meet Items 1 and 2 and shall be capable of providing a temperature range or dead band of at least 5°F within which the supply of heating and cooling energy to the zone is shut off or reduced to a minimum. Exception: Systems with thermostats that require manual changeover between heating and cooling modes.
  4. Thermostatic controls for all unitary single zone, air conditioners, heat pumps and furnaces, shall comply with the setback thermostat requirements of Section A6.207.1.3 or, if equipped with DDC to the Zone level, with the Automatic Demand Shed Controls of Section A6.207.5.5.

  Exception: Systems serving zones that must have constant temperatures to prevent degradation of materials, a process, plants or animals.

  A6.207.5.3 Heat pump controls. All heat pumps with supplementary electric resistance heaters shall be installed with controls that comply with Section A6.207.1.2.

  A6.207.5.4 Dampers for air supply and exhaust equipment. Outdoor air supply and exhaust equipment shall be installed with dampers that automatically close upon fan shutdown.

  Exceptions:

  1. Where it can be demonstrated to the satisfaction of the enforcing agency that the equipment serves an area that must operate continuously.

  2. Gravity and other nonelectrical equipment that has readily accessible manual damper controls.

  3. At combustion air intakes and shaft vents.

  4. Where prohibited by other provisions of law.

  A6.207.5.5 Automatic demand shed controls. HVAC systems with DDC to the Zone level shall be programmed to allow centralized demand shed for noncritical zones as follows:

  1. The controls shall have a capability to remotely setup the operating cooling temperature set points by 4 degrees or more in all noncritical zones on signal from a centralized contact or software point within an Energy Management Control System (EMCS).
  2. The controls shall remotely set down the operating heating temperature set points by 4 degrees or more in all noncritical zones on signal from a centralized contact or software point within an EMCS.
  3. The controls shall have capabilities to remotely reset the temperatures in all noncritical zones to original operating levels on signal from a centralized contact or software point within an EMCS.
  4. The controls shall be programmed to provide an adjustable rate of change for the temperature setup and reset.

  A6.207.6 Pipe insulation. The piping for all space- conditioning and service water-heating systems with fluid temperatures listed in Table A6.207.6-A shall have the amount of insulation specified in Subsection A6.207.6.1 or A6.207.6.2. Insulation conductivity shall be determined in accordance with ASTM C335 at the mean temperature listed in Table A6.207.6-A and shall be rounded to the nearest 1 / 100 Btu-inch per hour per square foot per °F.

  Insulation shall be protected from damage, including that due to sunlight, moisture, equipment maintenance and wind, including but not limited to, the following:

  Insulation exposed to weather shall be suitable for outdoor service, e.g., protected by aluminum, sheet metal, painted canvas or plastic cover. Cellular foam insulation shall be protected as above or painted with a coating that is water retardant and provides shielding from solar radiation that can cause degradation of the material.

  Insulation covering chilled water piping and refrigerant suction piping located outside the conditioned space shall include a vapor retardant located outside the insulation (unless the insulation is inherently vapor retardant), all penetrations and joints of which shall be sealed.

• CMC § 503.5.7.2 Medium relevance — show source text

  Individual or parallel pumps serving variable-flow heating-water or chilledwater systems, where the nameplate horsepower of the motor or combined parallel motors is not less than the power shown in Table E 503.5.7.2, shall have controls or devices that will result in pump motor demand of not more than 30 percent of design wattage at 50 percent of design water flow. The controls or devices shall be controlled as a function of desired flow or to

  maintain a minimum required differential pressure. Differential pressure shall be measured at or near the most remote heat exchanger or the heat exchanger requiring the greatest differential pressure. The differential pressure setpoint shall not exceed 110 percent of that required to achieve design flow through the heat exchanger. Where differential pressure control is used to comply with this section, and DDC systems are used, the setpoint shall be reset downward based on valve positions until one valve is nearly wide open.

  Exceptions:

  (1) Differential pressure set-point reset is not required where valve position is used to comply with Section E 503.5.7.4.

  (2) Variable-pump flow control is not required on heating-water pumps where more than 50 percent of annual heat is generated by an electric boiler.

  (3) Variable flow is not required for primary pumps in a primary/secondary system.

  (4) Variable flow is not required for a coil pump provided for freeze protection.

  (5) Variable flow is not required for heat recovery coil runaround loops. [ASHRAE 90.1:6.5.4.2]

  CHILLED WATER PUMPS IN THESE CLIMATE ZONES	HEATING WATER PUMPS IN THESE CLIMATE ZONES	MOTOR NAMEPLATE HORSEPOWER
  0A, 0B, 1A, 1B, 2B	NR	≥2 hp
  2A, 3B	NR	≥3 hp
  3A, 3C, 4A, 4B	7, 8	≥5 hp
  4C, 5A, 5B, 5C, 6A, 6B	3C, 5A, 5C, 6A, 6B	≥7.5 hp
  ─	4A, 4C, 5B	≥10 hp
  7, 8	4B	≥15 hp
  ─	2A, 2B, 3A, 3B	≥25 hp
  ─	1B	≥100 hp
  ─	0A, 0B, 1A	≥200 hp

  For SI units: 1 horsepower = 0.746 kW

• CMC § 90.1 Medium relevance — show source text

  [ASHRAE 90.1:6.5.4.1]

  2025 CALIFORNIA MECHANICAL CODE 439

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  APPENDIX E

  TABLE E 503.5.7.2

  PUMP FLOW CONTROL REQUIREMENTS

  [ASHRAE 90.1: TABLE 6.5.4.2]

  BOILER SYSTEM DESIGN INPUT, Btu/h	MINIMUM TURNDOWN RATIO
  ≥1 000 000 and≤5 000 000	3 to 1
  >5 000 000 and≤10 000 000	4 to 1
  >10 000 000	5 to 1

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  TABLE E 503.5.7

  BOILER TURNDOWN

  [ASHRAE 90.1: TABLE 6.5.4.1]

  For SI units: 1000 British thermal units per hour = 0.293 kW

  E 503.5.7.2 Hydronic Variable Flow Systems. Chilled- and hot-water distribution systems that include three or more control valves designed to modulate or step open and close as a function of load shall be designed for variable fluid flow and shall be capable of and configured to reduce pump flow rates to not more than the larger of 25 percent of the design flow rate or the minimum flow required by the heating/cooling equipment manufacturer for the proper operation of equipment. Individual or parallel pumps serving variable-flow heating-water or chilledwater systems, where the nameplate horsepower of the motor or combined parallel motors is not less than the power shown in Table E 503.5.7.2, shall have controls or devices that will result in pump motor demand of not more than 30 percent of design wattage at 50 percent of design water flow. The controls or devices shall be controlled as a function of desired flow or to

  maintain a minimum required differential pressure. Differential pressure shall be measured at or near the most remote heat exchanger or the heat exchanger requiring the greatest differential pressure. The differential pressure setpoint shall not exceed 110 percent of that required to achieve design flow through the heat exchanger. Where differential pressure control is used to comply with this section, and DDC systems are used, the setpoint shall be reset downward based on valve positions until one valve is nearly wide open.

  Exceptions:

  (1) Differential pressure set-point reset is not required where valve position is used to comply with Section E 503.5.7.4.

  (2) Variable-pump flow control is not required on heating-water pumps where more than 50 percent of annual heat is generated by an electric boiler.

  (3) Variable flow is not required for primary pumps in a primary/secondary system.

  (4) Variable flow is not required for a coil pump provided for freeze protection.

  (5) Variable flow is not required for heat recovery coil runaround loops. [ASHRAE 90.1:6.5.4.2]

• CMC § 1705.8 Medium relevance — show source text

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  2025 CALIFORNIA MECHANICAL CODE 349

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  GEOTHERMAL ENERGY SYSTEMS AND AMBIENT TEMPERATURE LOOPS

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  1705.8 Reduced Pressure. A pressure relief valve shall be installed on the low-pressure side of a hydronic piping system that has been reduced in pressure. The relief valve shall be set at the maximum pressure of the system design.

  1706.0 Specific System Components Design.

  1706.1 General. Heat pumps shall be in compliance with Table 1706.1, as applicable. Heat pumps shall also be listed and labeled in accordance with UL 1995 or UL 60335-2-40.

  Ground coupled and water source heat pumps shall be listed in accordance with AHRI/ASHRAE/ISO 13256-1 for water-to air heat pumps and AHRI/ASHRAE/ISO 13256-2 for water-towater heat pumps. DX heat pumps shall be listed in accordance with ASHRAE 194. All heat pump equipment used in DX systems shall comply with AHRI 870. Heat pumps shall be fitted with a means to indicate that the compressor is locked out.

  TABLE 1706.1

  HEAT PUMPS

  TYPE OF HEAT PUMP	STANDARDS
  Water-to-Air	AHRI/ASHRAE/ISO 13256-1
  Water-to-Water	AHRI/ASHRAE/ISO 13256-2

  1706.2 Heat Exchangers. Heat exchangers used for heat transfer or heat recovery shall protect the potable water system from being contaminated by the heat transfer medium. Singlewall heat exchangers shall comply with Section 1218.1. Double-wall heat exchangers shall separate the potable water from the heat transfer medium by providing a space between the two walls that are vented to the atmosphere.

  1706.3 Heat-Transfer Medium. The heat-transfer medium shall be compatible with components with which it comes into contact. Where antifreeze or corrosion inhibitors are used, such solutions shall be approved by the Authority Having Jurisdiction. The heat-transfer fluid flash point shall be not less than 50°F (27.8°C) above the maximum system operating temperature. For DX systems, the heat transfer medium shall be a refrigerant listed in ASHRAE 34 or this code. 1706.4 Insulation. The temperature of surfaces within reach of building occupants shall not exceed 140°F (60°C) unless they are protected by insulation. Where sleeves are installed, the sleeve insulation shall retain its full size over the length of the material being protected.

  1707.0 Installation Practices.

  1707.1 Prior to Construction. Documents for permits shall be submitted prior to the construction of a building system, or water well. Permits shall be issued by the Authority Having Jurisdiction. 1707.2 Equipment, Accessories, Components, and Materials. The mechanical equipment, accessories, components, and materials used shall be of the type and rating approved for the specific use.

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• CMC § 310.1.1 Medium relevance — show source text

  310.1.1 Condensate Pumps. Where approved by the Authority Having Jurisdiction, condensate pumps shall be installed in accordance with the manufacturer’s installation instructions. Pump discharge shall rise vertically to a point where it is possible to connect to a gravity condensate drain and discharged to an approved disposal point. Each condensing unit shall be provided with a separate sump and interlocked with the equipment to prevent the equipment from operating during a failure. Separate pumps shall be permitted to connect to a single gravity indirect waste where equipped with check valves and approved by the Authority Having Jurisdiction.

  310.2 Condensate Control. Where any equipment or appliance is installed in a space where damage is capable of resulting from condensate overflow, a drain line shall be provided and shall be drained in accordance with Section 310.1. An additional protection method for condensate overflow shall be provided in accordance with one of the following:

  (1) A water level detecting device that will shut off the equipment or appliance in the event the primary drain is

  EQUIPMENT CAPACITY IN TONS OF REFRIGERATION	MINIMUM CONDENSATE PIPE DIAMETER (inches)
  Up to 20	3⁄4
  21 – 40	1
  41 – 90	11⁄4
  91 – 125	11⁄2
  126 – 250	2

  For SI units: 1 ton of refrigeration = 3.52 kW, 1 inch = 25 mm

  The size of condensate waste pipes is for one unit or a combination of units, or as recommended by the manufacturer. The capacity of waste pipes assumes a [1] ⁄ 8 inch per foot (10.4 mm/m) or 1 percent slope, with the pipe running threequarters full at the following pipe conditions:

  Outside Air – 20%	Col2	Room Air – 80%	Col4
  DB	WB	DB	WB
  90°F	73°F	75°F	62.5°F

  For SI units: °C = (°F-32)/1.8

  blocked. Such detecting device shall be in accordance with the manufacturer’s installation instructions.

  (2) An additional watertight pan of corrosion-resistant material, with a separate drain line, installed beneath the cooling coil, unit, or the appliance to catch the overflow condensate due to a clogged primary condensate drain.

  (3) An additional separate drain line at a level that is higher than the primary drain line connection of the drain pan.

  (4) An additional watertight pan of corrosion-resistant material with a water level detection device installed beneath

  the cooling coil, unit, or the appliance to catch the overflow condensate due to a clogged primary condensate drain and to shut off the equipment.

  The additional pan or the additional drain line connection shall be provided with a drain pipe of not less than [3] ⁄ 4 of an inch (20 mm) nominal pipe size, discharging at a point that is readily observed.

  310.2.1 Protection of Appurtenances. Where insulation or appurtenances are installed where damage is capable of resulting from a condensate drain pan overfill, such installations shall occur above the rim of the drain

• CMC § 503.7.1 Medium relevance — show source text

  (8) Where a heat pump equipped with auxiliary internal electric resistance heaters is installed, controls shall be provided that prevent supplemental heater operation where the heating load is capable of being met by the heat pump alone during both steady-state operation and setback recovery. Supplemental heater operation shall be permitted during outdoor coil defrost cycles. The heat pump shall be controlled in accordance with one of the following:

  (a) A digital or electronic thermostat designed for heat pump use that energizes auxiliary heat where the heat pump has insufficient capacity

  2025 CALIFORNIA MECHANICAL CODE 419

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  APPENDIX E

  to maintain setpoint or to warm up the space at a sufficient rate.

  (b) A multistage space thermostat and an outdoor air thermostat wired to energize auxiliary heat on the last stage of the space thermostat and where outdoor air temperature is less than 40°F (4°C).

  Exceptions: Heat pumps that comply with the following:

  (1) Have a minimum efficiency regulated by NAECA.

  (2) In accordance with the requirements shown in Table E 503.7.1(2).

  (3) Include all usage of internal electric resistance heating.

  (9) The system controls shall not permit reheat or other form of simultaneous heating and cooling for humidity control.

  (10)Systems serving spaces other than residential spaces, that do not require continuous operation with a cooling or heating capacity more than 7000 Btu/h (2.1 kW) shall comply with Section E 503.4.6.3.1 and Section E 503.4.6.3.2.

  (11) Systems serving residential spaces other than hotel/motel guest rooms shall comply with Section E 503.4.6.3.1 and Section E 503.4.6.3.2 except for electric resistance heaters rated at 5000 Btu/h (1.5 kW) or less with a readily accessible manual control that lowers the set point or turns the unit off.

  (12) Systems serving hotel/motel guest rooms shall comply with Section E 503.4.6.3.5.

  (13) Except for piping within manufacturer’s units, HVAC piping shall be insulated in accordance with Table E 503.7.3(1) and Table E 503.7.3(2). Insulation exposed to weather shall be suitable for outdoor service, e.g., protected by aluminum, sheet metal, painted canvas, or plastic cover. Cellular foam insulation shall be protected as above or painted with a coating that is water retardant and provides shielding from solar radiation.

  (14) Ductwork and plenums shall be insulated in accordance with Table E 503.7.2 and shall be sealed in

  accordance with Section E 503.4.7.2.

  (15) Construction documents shall require a ducted system to be air balanced in accordance with industryaccepted procedures.

  (16) Outdoor air intake and exhaust systems shall comply with Section E 503.4.6.4 through Section E 503.4.6.5.

  (17) Where separate heating and cooling equipment serves the same temperature zone, thermostats shall be interlocked to prevent simultaneous heating and cooling.

  (18) Systems with a design supply air capacity more than 10 000 ft [3] /min (4.7195 m [3] /s) shall have optimum start controls.

• CMC § 1215.0 Medium relevance — show source text

  HYDRONIC SPACE HEATING . . . . . . . . . . . . . . . . . 1215.0

  HYDRONICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chapter 12

  Auxiliary systems . . . . . . . . . . . . . . . . . . . . . . . . 1220.0

  Appliances and equipment . . . . . . . . . . . . . . . . . 1207.0

  Boilers . . . . . . . . . . . . . . . . . . 1207.2, 1207.2.1, 1207.2.2

  Circulators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1208.0

  Clearance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1221.7

  Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210.0

  Embedded piping and joints . . . . . . . . . . . . . . . . 1221.2

  Expansion tanks . . . . . . . . . . . . . . . . . . . . . . . . . 1209.0

  Hangers and supports. . . . . . . . . . . . . . . . . . . . . 1210.3

  Heat emitters . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1201.7

  Heat pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1207.5

  Heat sources . . . . . . . . . . . . . . . . . . . . . . . . . . . 1203.1

  Heat transfer fluid . . . . . . . . . . . . . . . . . . 1201.3, 1204.7

  Identification of piping . . . . . . . . . . . . . . . . . . . . . 1204.0

  Installation . . . . . . . . . . . . . . . . . . . . . . . 1205.0, 1221.0

  Insulation. . . . . . . . . 1201.2, 1217.8.2, 1217.10, 1220.4.7

  Joints and connections . . . . . . . . . . . . . . . . . . . . 1211.0

  Materials . . . . . . . . . . . . . . . . . . . . 1210.0, Table 1210.1

  Protection of potable water supply . . . . . . . . . . . 1202.0

  Radiant heating and cooling . . . . . . . . . . . . . . . . 1217.0

  Snow melt systems . . . . . . . . . . . . . . . . 1220.4, 1220.0,

  1217.8.2, Table 1220.4.2

• CMC § 503.7.1 Medium relevance — show source text

  ** Heat pumps equipped with internal electric resistance heaters shall have controls that prevent supplemental heater operation where the heating load is capable of being met by the heat pump alone during both steady-state operation and setback recovery. Supplemental heater operation shall be permitted during outdoor coil defrost cycles. Exception: Heat pumps whose minimum efficiency is regulated by U.S. National Appliance Energy Conservation Act (NAECA) and whose ratings are in accordance with the requirements shown in Table E 503.7.1(2) and includes the use of an internal electric resistance heating. [ASHRAE 90.1:6.4.3.5] E 503.4.6.7 Humidification and Dehumidifica- tion Control. Humidification and dehumidification

  control shall be in accordance with Section E 503.4.6.7.1 through Section E 503.4.6.7.3. E 503.4.6.7.1 Dehumidification. Humidistatic controls shall not use mechanical cooling to reduce the humidity below the lower of a dew point of 55°F (12.8°C) or relative humidity of 60 percent in the coldest zone served by the system. Exceptions: (1) Lower humidity shall be permitted when operating mechanical cooling for temperature control.

  (2) Systems serving zones where specific humidity levels are required, such as museums and hospitals, and approved by the Authority Having Jurisdiction or required by accreditation standards, and where humidistatic controls are capable of and configured to maintain a dead band of at least 10 percent relative humidity where no active humidification or dehumidification takes place.

  (3) Systems serving zones where humidity levels are required to be maintained with precision of not more than ±5 percent relative humidity to comply with applicable codes or accreditation standards or as approved by the Authority Having Jurisdiction.

  [ASHRAE 90.1:6.4.3.6.1]

  E 503.4.6.7.2 Humidification. Humidistatic controls shall not use fossil fuel or electricity to produce relative humidity above 30 percent in the warmest zone served by the system.

  Exceptions:

  (1) Systems serving zones where specific humidity levels are required, such as museums and hospitals, and approved by the Authority Having Jurisdiction or required by accreditation standards, and where humidistatic controls are capable of and configured to maintain a dead band of at least 10 percent relative humidity where no active humidification or dehumidification takes place.

  TABLE E 503.4.6.4.2 MAXIMUM DAMPER LEAKAGE [1, 2]

  (cubic foot per minute per square foot) at 1.0 inch water gauge

  [ASHRAE 90.1: TABLE 6.4.3.4.3]

• CMC § 110.3 Medium relevance — show source text

  SECTION 110.3—MANDATORY REQUIREMENTS FOR SERVICE WATER-HEATING SYSTEMS AND EQUIPMENT

  (a) Certification by manufacturers. Any service water- heating system or equipment may be installed only if the manufacturer has certified that the system or equipment complies with all of the requirements of this subsection for that system or equipment.

  1. Temperature controls for service water-heating systems. Service water-heating systems shall be equipped with automatic temperature controls capable of adjustment from the lowest to the highest acceptable temperature settings for the intended use as listed in Table 3, Chapter 50 of the ASHRAE Handbook, HVAC Applications Volume or Table 613.1 of the Cali- fornia Plumbing Code for healthcare facilities. Exception to Section 110.3(a)1: Residential occupancies.

  (b) Efficiency. Equipment shall meet the applicable requirements of the Appliance Efficiency Regulations as required by Section 110.1, subject to the following:

  1. If more than one standard is listed in the Appliance Efficiency Regulations, the equipment shall meet all the standards listed; and

  2. If more than one test method is listed in the Appliance Efficiency Regulations, the equipment shall comply with the applicable standard when tested with each test method; and

  3. Where equipment can serve more than one function, such as both heating and cooling, or both space heating and water heating, it shall comply with all the requirements applicable to each function; and

  4. Where a requirement is for equipment rated at its “maximum rated capacity” or “minimum rated capacity,” the capacity shall be as provided for and allowed by the controls, during steady-state operation.

  (c) Installation. Any service water-heating system or equipment may be installed only if the system or equipment complies with all of the applicable requirements of this subsection for the system or equipment.

  1. Outlet temperature controls. On systems that have a total capacity greater than 167,000 Btu/hr, outlets that require higher than service water temperatures as listed in the ASHRAE Handbook, Applications Volume, shall have separate remote heaters, heat exchangers or boosters to supply the outlet with the higher temperature. Exception to Section 110.3(c)1: Systems covered by California Plumbing Code Section 613.0 shall instead follow the requirements of that section.
  2. Controls for hot water distribution systems. Service hot water systems with circulating pumps or with electrical heat trace systems shall be capable of automatically turning off the system. Exception to Section 110.3(c)2: Systems serving healthcare facilities.
  3. Insulation. Unfired service water heater storage tanks and backup tanks for solar water-heating systems shall have: A. External insulation with an installed R -value of at least R-3.5; or

  B. Internal and external insulation with a combined R -value of at least R-16; or

  C. The heat loss of the tank surface based on an 80°F water-air temperature difference shall be less than 6.5 Btu per hour per square foot. 4. Water heating recirculation loops serving multiple dwelling units, high-rise residential, hotel/motel, and nonresiden- tial occupancies. A water heating recirculation loop is a type of hot water distribution system that reduces the time needed to deliver hot water to fixtures that are distant from the water heater, boiler or other water heating equipment. The recirculation loop is comprised of a supply portion, connected to branches that serve multiple dwelling units, guest rooms, or fixtures and a return portion that completes the loop back to the water heating equipment.

• CMC § 160.3 Medium relevance — show source text

  The perimeter system has at least one thermostatic control for each building orientation of 50 feet or more; and iv. The perimeter system is controlled by at least one thermostat located in one of the zones served by the system. B. Criteria for zonal thermostatic controls. The individual thermostatic controls required by Section 160.3(a)2A shall meet the following requirements as applicable: i. Where used to control comfort heating, the thermostatic controls shall be capable of being set, locally or remotely, down to 55°F or lower. ii. Where used to control comfort cooling, the thermostatic controls shall be capable of being set, locally or remotely, up to 85°F or higher. iii. Where used to control both comfort heating and comfort cooling, the thermostatic controls shall meet Items i and ii and shall be capable of providing a temperature range or deadband of at least 5°F within which the supply of heating and cooling energy to the zone is shut off or reduced to a minimum. Exception to Section 160.3(a)2Biii: Systems with thermostats that require manual changeover between heating and cooling modes. iv. Thermostatic controls for all single zone air conditioners and heat pumps shall comply with the requirements of Sections 110.2(c) and 110.12(a) and, if equipped with DDC to the zone level, with the automatic demand shed controls of Section 110.12(b). Exception to Section 160.3(a)2Biv: Package terminal air conditioners, package terminal heat pumps, room air conditioners and room air-conditioner heat pumps. C. Heat pump controls. All heat pumps with supplementary electric resistance heaters shall be installed with controls that comply with Section 110.2(b).

  NOTE: Authority: Sections 25213, 25218, 25218.5, 25402 and 25402.1, Public Resources Code . Reference: Sections 25007, 25008, 25218.5, 25310, 25402, 25402.1, 25402.4, 25402.5, 25402.8 and 25943, Public Resources Code .

  D. Shut-off and reset controls for space-conditioning systems. Each space-conditioning system shall be installed with controls that comply with the following: i. The control shall be capable of automatically shutting off the system during periods of nonuse and shall have: a. An automatic time switch control device complying with Section 110.9, with an accessible manual override that allows operation of the system for up to 4 hours; or b. An occupancy sensor; or c. A 4-hour timer that can be manually operated. ii. The control shall automatically restart and temporarily operate the system as required to maintain: a. A setback heating thermostat setpoint if the system provides mechanical heating; and Exception to Section 160.3(a)2Diia: Thermostat setback controls are not required in multifamily buildings in areas where the Winter Median of Extremes outdoor air temperature determined in accordance with Section 170.2(c)1C is greater than 32°F. b. A setup cooling thermostat setpoint if the system provides mechanical cooling.

  212 2025 CALIFORNIA ENERGY CODE

  on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

  MULTIFAMILY BUILDINGS—MANDATORY REQUIREMENTS