This section addresses the requirements for heating equipment, including furnaces, boilers, heat pumps, and electric resistance equipment.
The efficiency of most heating equipment is regulated by the National Appliance Energy Conservation Act of 1987 (NAECA, the federal appliance standard) and the California Appliance Efficiency Regulations. These regulations are not contained in the Energy Code but are published separately. These regulations are referenced in §110.1. The Appliance Efficiency Regulations include definitions for all types of equipment and are regularly updated.
Note: The Appliance Efficiency Regulations that are in effect when the building permit is applied for will determine the minimum efficiency of the appliances identified in the compliance documentation.
The energy efficiency of other equipment is regulated by §110.2(a). Also, see the Nonresidential Compliance Manual for more information on larger equipment.
- Gas and Oil-Fired Furnaces
The Appliance Efficiency Regulations require gas- and oil-fired central furnaces with outputs less than 225,000 Btu/h to be rated according to the associated annual fuel utilization efficiency (AFUE). Gas- and oil-fired central furnaces with outputs greater than or equal to 225,000 Btu/h are rated according to the respective thermal (or steady-state) efficiency. Refer to Table 4-1 for the applicable efficiency requirements.
Appliance | Rated Input (Btu/h) | Minimum Efficiency (%)AFUE | Minimum Efficiency (%) Thermal Efficiency |
Weatherized gas central furnaces with single phase electrical supply | < 225,000 | 81 | NA |
Non-weatherized gas central furnaces with single phase electrical supply | < 225,000 | 80 | NA |
Weatherized oil central furnaces with single phase electrical supply | < 225,000 | 78 | NA |
Non-weatherized oil central furnaces with single phase electrical supply | < 225,000 | 83 | NA |
Gas central furnaces | ≥ 225,000 | NA | 81 |
Oil central furnaces | ≥ 225,000 | NA | 82 |
Source: California Appliance Efficiency Regulations Title-20 - Table E-5 and E-6
Noncentral gas furnaces and space heaters manufactured on or after April 16, 2013, shall be certified to have AFUE values greater than or equal to those listed in Table 4-2.
Type | Capacity (Btu/h) | AFUE |
Wall Furnace (fan type) | ≤ 42,000 | 75% |
Wall Furnace(fan type) | > 42,000 | 76% |
Wall Furnace(gravity type) | ≤ 27,000 | 65% |
Wall Furnace(gravity type) | > 27,000 to ≤ 46,000 | 66% |
Wall Furnace(gravity type) | > 46,000 | 67% |
Floor Furnace | ≤ 37,000 | 57% |
Floor Furnace | > 37,000 | 58% |
Room Heater | ≤20,000 | 61% |
Room Heater | > 20,000 to ≤ 27,000 | 66% |
Room Heater | > 27,000 to ≤ 46,000 | 67% |
Room Heater | > 46,000 | 68% |
Source: California Appliance Efficiency Regulations Title 20 - Table E-2
B. Heat Pumps and Electric Heating
Heat pumps shall be certified to have a HSPF or coefficient of performance (COP) equal to or better than those listed in Table 4-3.
There are no minimum appliance efficiency standards for electric-resistance or electric-radiant heating systems.
C. Gas- and Oil-Fired Central Boilers and Electric Boilers
Gas- and oil-fired central boilers shall be certified to have and AFUE or Combustion Efficiency equal to or better than those listed in Table 4-4.
Equipment Type | Reference | Configuration/Size | Minimum Heating Efficiency |
Packaged terminal heat pumps (heating mode) | Newly constructed or newly conditioned buildings or additions | 3.7-(0.052 x Cap 1 /1000) = COP | |
Packaged terminal heat pumps (heating mode) | Replacements | 2.9-(0.026 x Cap 1 /1000) = COP | |
Single-phase air source heat pumps (NAECA) | Table C-3 | < 65,000 Btu/h cooling | Packaged 8.0 HSPF Split 8.2 HSPF |
Single-phase air source heat pumps (NAECA) | Table C-3 | Space constrained < 65,000 Btu/h cooling capacity | 7.4 HSPF |
Single-phase air source heat pumps (NAECA) | Table C-3 | Small duct, high velocity < 65,000 Btu/h cooling capacity | 7.2 HSPF |
Three-phase air source heat pumps | Table C-4 | Split-system < 65,000 Btu/h | 8.2 HSPF |
Three-phase air source heat pumps | Table C-4 | ≥ 65,000 and <135,000 | 3.4 COP |
Three-phase air source heat pumps | Table C-4 | ≥ 135,000 and <240,000 | 3.3 2 COP 3.4 3 COP |
Three-phase air source heat pumps | Table C-4 | ≥ 240,000 and <760,000 | 3.2 COP |
Water-source heat pumps | Table C-5 | ≥ 65,000 and < 135,000 Btu/h | 4.3 COP |
Water-source heat pumps | ≥ 135,000 Btu/h, < 240,000 Btu/h | 2.9 COP | |
Single package vertical heat pumps | Table C-6 | < 65,000 single-phase | 3.0 COP |
Single package vertical heat pumps | Table C65 | < 65,000 3-Phase | 3.3 COP |
Single package vertical heat pumps | Table C-6 | ≥ 65,000 and < 135,000 | 3.0 COP |
Single package vertical heat pumps | Table C-6 | ≥ 135,000 and < 240,000 | 3.0 COP |
1. Cap = Cooling Capacity of the product in Btu/h. If the unit’s capacity is less than 7,000 Btu/h, use 7,000 Btu/h in the calculation. If the unit’s capacity is greater than 15,000 Btu/h, use 15,000 Btu/h in the calculation.
2. Electric resistance heating or no heating
3. All other types of heating
Source: California Appliance Efficiency Regulation Title 20 and Energy Code Table C-3, C-4, C-5, C-6; Title 24 Table 110.2-B, 110.2-E
Appliance | Rated Input (Btu/h) | Minimum Efficiency (%) | Efficiency Metric |
Gas steam boilers with single-phase electrical supply | < 300,000 | 82 ¹ | AFUE |
Gas hot water boilers with single-phase electrical supply | < 300,000 | 84 ¹,² | AFUE |
Oil steam boilers with single-phase electrical supply | < 300,000 | 85 | AFUE |
Oil hot water boilers with single-phase electrical supply | < 300,000 | 86 ² | AFUE |
Electric steam residential boilers | < 300,000 | NA | NA |
Electric hot water residential boilers | < 300,000 | NA | NA |
All other boilers with single-phase electrical supply | < 300,000 | NA | NA |
1. No constant burning pilot light design standard.
2. Automatic means for adjusting temperature design standard.
Source: California Appliance Efficiency Regulations Title 20 Table E-3
Appliance | Rated Input (Btu/h) | Minimum Thermal Efficiency (%) | Minimum Combustion Efficiency (%) |
Steam boilers; gas-fired, except natural draft; | ≥ 300,000 | 79 | 81 |
Steam boilers; gas-fired, natural draft | ≥ 300,000 | 79 | 81 |
Steam boilers; oil-fired | ≥ 300,000 | 81 | 82 |
Source: California Appliance Efficiency Regulations Title 20 Table E-4
§150.0(i), §110.2(b), Exceptions to §110.2(b), Exception to §110.2(c)
Heating systems must be controlled by a central energy management control system (EMCS) or by a setback thermostat. The setback thermostat must be capable of allowing the occupant to program temperature set points for at least four periods within a 24-hour time span.
The exception to this is gravity gas wall heaters, floor heaters, room heaters, fireplaces, wood stoves, and noncentral electric heaters.
Any heat pump with supplementary electric resistance heating requires controls with two capabilities to limit the electric resistance heating. The first required capability is to set the cut-on and cut-off temperatures for the heat pump and supplementary electric resistance heating at different levels.
For example, if the heat pump begins heating when the inside temperature reaches 68°F, the electric resistance heating may be set to come on if the temperature goes below 65°F if the heat pump alone could not maintain the set point of 68°F. Also, there must be an “off” mode that automatically shuts off the electric resistance when the inside temperature reaches 68°F.
The second control capability must prevent the supplementary electric resistance heater from operating if the heat pump alone can meet the heating load, except during defrost. There is a limited exception to this second function for “smart thermostats” that provide intelligent recovery, staging, ramping, or another control mechanism that prevents the unnecessary operation of supplementary electric resistance heating when the heat pump alone can meet the heating load.
To meet the thermostat requirements, a thermostat for a heat pump must be a “smart thermostat” that minimizes the use of supplementary heating during startup and enables recovery from setbacks.
Note: Room air conditioner heat pumps are not required to comply with the thermostat requirements.
The Energy Code does not set limits on the sizing of heating equipment, but does require that heating loads be calculated for new heating systems. Oversized equipment typically operates less efficiently and can create comfort problems due to excessive cycling and improper airflow.
Acceptable load calculation procedures include methods described in the following publications:
- The ASHRAE Handbook – Equipment
- The ASHRAE Handbook – Applications
- ASHRAE Handbook – Fundamentals
- The SMACNA Residential Comfort System Installation Manual
- ACCA Manual J
The Energy Code requires that the outdoor design conditions for load calculations be selected from Reference Joint Appendix (JA) JA2 and that the indoor design temperature for heating load calculations be 68°F.
The outdoor design temperature must be no lower than the “heating winter median of extremes,” as listed in JA2.
If the actual city location for a project is not included in JA2, or if the data given for a particular city do not match the conditions at the actual site as well as that given for another nearby city, consult the local building department for guidance.
The load calculations must be submitted with the compliance documentation when requested by the building department.
The load calculations may be prepared by 1) a mechanical engineer, 2) the mechanical contractor who is installing the equipment or 3) someone who is qualified to do so in the State of California according to Division 3 of the Business and Professions Code.
The Business and Professions Code does not prohibit an unlicensed person from preparing plans, drawings, or specifications for single-family dwelling units of wood-frame construction not more than two stories and basement in height, or for certain buildings containing no more than four dwelling units of wood-frame construction not more than two stories and basement in height.
Fan-type central furnaces may not have a continuously burning pilot light. This requirement does not apply to wall furnaces, floor furnaces, or any gravity-type furnace. Household cooking appliances also must not have a continuously burning pilot light, except for those without an electrical supply voltage connection and in which each pilot consumes less than 150 Btu/h.
Larger gas-fired and oil-fired forced air furnaces with input ratings equal to or greater than 225,000 Btu/h (which is bigger than a typical residential furnace) must also have an intermittent ignition device (IID) and either power venting or a flue damper.
A vent damper is an acceptable alternative to a flue damper for furnaces where combustion air is drawn from the conditioned space. All furnaces with input ratings equal to or greater than 225,000 Btu/h, including electric furnaces, that are not within the conditioned space must have jacket losses not exceeding 0.75 percent of the input rating.
§150.0(j)1, §150.0(j)2, §120.3
The piping for heat pumps and for steam and hydronic heating systems shall meet the insulation requirements provided below in Table 4-5a-f when the insulation is outside conditioned space, it requires protection from damage caused by environmental conditions. The insulation must be rated for outdoor use or covered with a material that can withstand outdoor conditions. Examples of these types of coverings are aluminum, sheet metal, painted canvas, plastic cover, or, if the insulation is cellular foam, a coating that is water-retardant and shields from solar radiation. Moreover, the insulation used for the refrigerant suction line of a heat pump must be Class I or Class II vapor retardant.
|
Fluid Oper. Temp. Range (°F)
|
Insulation Conduct (Btu·in/h·ft 2 °F)
|
Insulation Mean Rating Temp. (°F)
|
Pipe Dia. (in) < 1
|
Pipe Dia. (in)
1 to <1.5 |
Pipe Dia. (in) 1.5 to < 4
|
Pipe Dia. (in)
4 to < 8 |
Pipe Dia. (in) 8 ≤
|
|
Above 350
|
0.32-0.34
|
250
|
4.5
|
5.0
|
5.0
|
5.0
|
5.0
|
|
251-350
|
0.29-0.32
|
200
|
3.0
|
4.0
|
4.5
|
4.5
|
4.5
|
|
201-250
|
0.27-0.30
|
150
|
2.5
|
2.5
|
2.5
|
3.0
|
3.0
|
|
141-200
|
0.25-0.29
|
125
|
1.5
|
1.5
|
2.0
|
2.0
|
2.0
|
|
105-140
|
0.22-0.28
|
100
|
1.0
|
1.5
|
1.5
|
1.5
|
1.5
|
Source: Energy Code Table 120.3-A
|
Fluid Oper. Temp. Range (°F)
|
Insulation Conduct.
(Btu·in/h·ft 2 °F) |
Insulation Mean Rating Temp.
(°F) |
Pipe Dia.
(in) < 1 |
Pipe Dia.
(in) 1 to <1.5 |
Pipe Dia.
(in) 1.5 to < 4 |
Pipe Dia.
(in) 4 to < 8 |
Pipe Dia.
(in) 8 ≤ |
|
Above 350
|
0.32-0.34
|
250
|
R 37
|
R 41
|
R 37
|
R 27
|
R 23
|
|
251-350
|
0.29-0.32
|
200
|
R 24
|
R 34
|
R 35
|
R 26
|
R 22
|
|
201-250
|
0.27-0.30
|
150
|
R 21
|
R 20
|
R 17.5
|
R 17
|
R 14.5
|
|
141-200
|
0.25-0.29
|
125
|
R 11.5
|
R 11
|
R 14
|
R 11
|
R 10
|
|
105-140
|
0.22-0.28
|
100
|
R 7.7
|
R 12.5
|
R 11
|
R 9
|
R 8
|
Source: Energy Code Table 120.3-A
|
Fluid Oper. Temp. Range
(°F) |
Insulation Conduct.
(Btu·in/ h·ft 2 °F) |
Insulation Mean Rating Temp.
(°F) |
Pipe Dia.
(in) < 1 |
Pipe Dia.
(in) 1 to <1.5 |
Pipe Dia.
(in) 1.5 to < 4 |
Pipe Dia.
(in) 4 to < 8 |
Pipe Dia.
(in) 8 ≤ |
|
40-60
|
0.21-0.27
|
75
|
0.75
|
0.75
|
1.0
|
1.0
|
1.0
|
|
Below 40
|
0.20-0.26
|
50
|
1.0
|
1.5
|
1.5
|
1.5
|
1.5
|
Source: Energy Code Table 120.3-A
|
Fluid Oper. Temp. Range
(°F) |
Insulation Conduct.
(Btu·in/ h·ft 2 °F) |
Insulation Mean Rating Temp.
(°F) |
Pipe Dia.
(in) < 1 |
Pipe Dia.
(in) 1 to <1.5 |
Pipe Dia.
(in) 1.5 to < 4 |
Pipe Dia.
(in) 4 to < 8 |
Pipe Dia.
(in) 8 ≤ |
|
40-60
|
0.21-0.27
|
75
|
R-6
|
R-5
|
R-7
|
R-6
|
R-5
|
|
Below 40
|
0.20-0.26
|
50
|
R-8.5
|
R-12
|
R-12
|
R-10
|
R-9
|
Source: Energy Code Table 120.3-A
|
Fluid Oper. Temp. Range
(°F) |
Insulation Conduct.
(Btu·in/ h·ft 2 °F) |
Insulation Mean Rating Temp.
(°F) |
Pipe Dia.
(in) < 1 |
Pipe Dia.
(in) 1 to <1.5 |
Pipe Dia.
(in) 1.5 to < 4 |
Pipe Dia.
(in) 4 to < 8 |
Pipe Dia.
(in) 8 ≤ |
|
40-60
|
0.21-0.27
|
75
|
0.5
|
0.5
|
1.0
|
1.0
|
1.0
|
|
Below 40
|
0.20-0.26
|
50
|
1.0
|
1.5
|
1.5
|
1.5
|
1.5
|
Source: Energy Code Table 120.3-A
|
Fluid Oper. Temp. Range
(°F) |
Insulation Conduct. (Btu·in/h·ft 2 °F)
|
Insulation Mean Rating Temp.
(°F) |
Pipe Dia.
(in) < 1 |
Pipe Dia.
(in) 1 to <1.5 |
Pipe Dia.
(in) 1.5 to < 4 |
Pipe Dia.
(in) 4 to < 8 |
Pipe Dia.
(in) 8 ≤ |
|
40-60
|
0.21-0.27
|
75
|
R-3
|
R-3
|
R-7
|
R-6
|
R-5
|
|
Below 40
|
0.20-0.26
|
50
|
R-8.5
|
R-12
|
R-12
|
R-10
|
R-9
|
Source: Energy Code Table 120.3-A
Prescriptive component compliance requires the installation of a gas heating system or heat pump, depending on the climate zone, that meets minimum energy efficiency ratings (See Table 4-1 through Table 4-4).
The heating system type must be a heat pump in climate zones 3, 4, 13, and 14. There are no restrictions on the type of heat pump that can be installed if it meets the minimum efficiency rating requirements. For all other climate zones, the heating system can be either a heat pump or a gas heating system.
Supplemental heating systems are allowed prescriptively, and the designer may elect to provide supplemental heating to a space such as a bathroom. In this instance, the supplemental heating system must be installed in a space that is served directly or indirectly by the primary heating system and must have a thermal capacity of less than 2 kilowatts (kW) or 7,000 Btu/h while being controlled by a time-limiting device not exceeding 30 minutes.
Electric resistance and electric radiant heating installations are not allowed as the primary heating system when using the prescriptive compliance approach.
Through the performance compliance approach there is one option for receiving compliance credit related to the heating system.
Heating system efficiencies are explained in Section 4.2.1.1. The minimum efficiency is required to be met for prescriptive compliance or performance compliance. When the performance compliance approach is used, additional compliance credit may be available from higher efficiency heating equipment which can be used to offset less efficient building features.
When a heat pump is providing space heating, if the efficiency used for compliance is higher than the minimum required HSPF, the system efficiency must be verified by a HERS Rater. Moreover, because the capacity of the heat pump affects the amount of back-up electric resistance heating required to attain and maintain comfort conditions, if the capacity proposed for compliance is different than the default capacity used in the performance compliance software, the Air Conditioning, Heating, and Refrigeration Institute (AHRI) ratings for heating capacity of the installed heat pump must be verified by a HERS Rater to confirm the heating capacities at 47 degrees F and 17 degrees F are equal or greater than the heating capacities given on the certificate of compliance (CF1R). See RA3.4 for more information about this HERS verification