4.2   Heating Equipment      

This section addresses the requirements for heating equipment, including furnaces, boilers, heat pumps and electric resistance equipment.   

4.2.1    Mandatory Measures for Heating Equipment    

A.   Equipment Efficiency

The efficiency of most heating equipment is regulated by NAECA (the federal appliance standard) and the California Appliance Efficiency Regulations. These regulations are not contained in the Building Energy Efficiency Standards but are published separately. These regulations are referenced in §110.1. The Appliance Efficiency Regulations include definitions for all types of equipment and are scheduled to be updated January 1, 2015, which may change the minimum efficiencies of most equipment. 

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.

1.   Gas and Oil-Fired Furnaces

The current Appliance Efficiency Regulations require that the Annual Fuel Utilization Efficiency (AFUE) of all new gas and oil-fired central furnaces with a single phase electrical supply be at least 78% with an output capacity less than 225,000 Btu/hr. 

Gas and oil-fired central furnaces with outputs greater than or equal to 225,000 Btu/hr are rated according to their Thermal (or Steady State) Efficiency.  The minimum Thermal Efficiency for large gas furnaces is 80% and 81% for large oil-fired central furnaces.

Table 4-1 – Minimum Efficiency for Gas and Oil-Fired Central Furnaces

Source: California Appliance Efficiency Regulations Title-20 - Table E-4

Non-central gas furnaces and space heaters shall be certified to have AFUE values greater than or equal to those 'listed in below:

Table 4-2 – Minimum Heating Efficiency for Non-Ducted, Non-Central Gas Fired Heating Equipment

Source: California Appliance Efficiency Regulations Title-20 - Table E-2

2.   Heat Pumps and Electric Heating

Heat pumps shall be certified to have a HSPF or COP equal to or better than those 'listed in Table 4-3 below:

Table 4-3 – Minimum Heating Efficiency for Heat Pumps

Source: California Appliance Efficiency Regulation and Energy Efficiency Standards  Title-20               

There are no minimum appliance efficiency standards for electric-resistance or electric-radiant heating systems.

3.   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 below:

Table 4-4 – Minimum Efficiency for Gas and Oil Fired Central Boilers

Source:  California Appliance Efficiency Regulations Title-20 Table E-3

B.   Heating System Controls

All unitary heating systems, including heat pumps, must be controlled by a setback thermostat. These thermostats must be capable of allowing the occupant to program the temperature set points for at least four different periods in 24 hours.  For example, the setback thermostat could be programmed at specific temperature starting at 6:30 am, 9:00 am, 4:30 pm and 9:00 pm, thus allowing for four periods within 24 hours. 

If the heating system is integrated into a central energy management control system (EMCS), then that system does not need to comply with the set back requirements.  Additionally, all gravity gas wall heaters, floor heaters, room heaters and fireplaces, decorative gas appliances, wood stoves and non-central electric heaters do not need to be controlled by a setback thermostat.

Any heat pump with supplementary electric resistance heating must have controls that have two capabilities to limit the electric resistance heating. The first is to set the cut-on and cut-off temperatures for compression and supplementary heating at different levels.

For example, if the heat pump begins heating when the inside temperature reaches 68°F, the electric resistance heating is set to come on if the temperature gets below 65°F; and there is an opposite off mode such that if the heat pump shuts off when the temperature reaches 72°F, the back-up heating shuts off at 68°F.

The second control capability prevents the supplementary electric resistance heater from operating when 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 the following: 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 recovery from setbacks.

Note: Room air conditioner heat pumps are not required to comply with the thermostat requirements.

C.   Equipment Sizing

The Standards do not set limits on the sizing of heating equipment, but they do 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 high airflow.

Acceptable load calculation procedures include methods described in

1.   The ASHRAE Handbook – Equipment,

2.   The ASHRAE Handbook – Applications,

3.   The ASHRAE Handbook – Fundamentals,

4.   The SMACNA Residential Comfort System Installation 'Manual, or

5.   ACCA Manual J.

The Standards require that the outdoor design conditions for load calculations be selected from Reference Joint Appendix 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 the Reference Joint Appendix JA2.

If the actual city location for a project is not included in the Reference Joint Appendix JA2, or if the data given for a particular city does 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.

D.   Furnace Temperature Rise

High temperature rise in a furnace is an indicator of low airflow and/or over specification firing rate. High temperature rise causes low efficiency and is potentially damaging to the furnace. Central forced-air heating furnace installations must be configured to operate at or below the furnace manufacturer's maximum inlet-to-outlet temperature rise specification.

E.   Standby Losses and Pilot Lights

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/hr.

Larger gas-fired and oil-fired forced air furnaces with input ratings ≥ 225,000 Btu/h (which is bigger than a typical residential furnace) must also have an intermittent ignition or interrupted 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 ≥ 225,000 Btu/h, including electric furnaces, that are not located within the conditioned space must have jacket losses not exceeding 0.75 percent of the input rating.

F.   Pipe Insulation

The piping for heat pumps and for both steam and hydronic heating systems with an operating pressure above 15 psig (103kPa) shall meet the requirements from Table 4-5, which can be found below.  When the insulation is located outside conditioned space it is required to be protected from damage caused by environmental conditions.  The insulation must be rated for outdoor use or covered with a material that can withstand the 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.  Additionally, the insulation used for the refrigerant suction line of a heat pump must be Class I or Class II vapor retarding.  If the insulation is not Class I or Class II, then the insulation must be installed at the required thickness that would qualify it as a Class I or Class II vapor retarder.

Table 4-5 - Insulation Requirements for Heating System Piping

From Table 120.3 A of the Building Energy Efficiency Standards Title-20

4.2.2    Prescriptive Requirements for Heating Equipment    

Prescriptive Component Package A requires that a gas heating system or a heat pump be installed. The minimum energy efficiency of the heating equipment is specified by the mandatory measures (see above).

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, supplemental heating system must be installed in a space that is served by the primary heating system and must have a thermal capacity of less than 2 kW or 7,000 Btu/hr while being controlled by a time-limiting device not exceeding 30 minutes.  Electric resistance and electric radiant heating is only allowed to be installed as the primary heating system when using the performance compliance method as described in Section 4.2.3.

Using the prescriptive compliance approach, no additional credit is given for selecting equipment that is higher than what is required by the prescriptive component package.

4.2.3    Compliance Options for Heating Equipment    

There is one option for receiving compliance credit related to the heating system.  This credit is available through the performance compliance method.

High Efficiency Heating

Heating system efficiencies are explained above in Section 4.2.2 and the minimum efficiency is required per the prescriptive package. With the performance compliance method, compliance credit is awarded for selecting higher efficiency heating equipment, such as a high efficiency furnace or heat pump. With a furnace, for example, selecting an AFUE higher than 78 will result in compliance credit which can then be used to offset other building features that do not satisfy the prescriptive requirements but that do comply with the mandatory requirements.