HVAC KnowZone Glossary

AC Air conditioner AHRI Air-Conditioning, Heating, and Refrigeration Institute. AHRI is the trade association representing manufacturers of air conditioning, heating and commercial refrigeration equipment. AHRI’s 300+ member companies, including Rheem, account for over 90 percent of the residential and commercial air conditioning, space heating, water heating and commercial refrigeration equipment manufactured and sold in North America. AIM ACT American Innovation and Manufacturing Act. AIM was enacted into law in 2020. It authorizes a 15-year phasedown of hydrofluorocarbons (HFCs) across a variety of applications, including HVAC. Refer to HFC for more details. ASHRAE American Society of Heating, Refrigerating and Air-Conditioning Engineers. ASHRAE is a global society advancing human well-being through sustainable technology for the modern environment. A2L A2L is a refrigerant classification from ASHRAE that means mildly flammable. It is a class of refrigerants with lower toxicity and flammability than A2 or A3 refrigerants. Due to their mildly flammable characteristics, A2L refrigerants require updates to standards and building codes to allow for safe installation. It is expected that A2L will become the standard refrigerant for 2025 HVAC products. BTU British Thermal Unit. The amount of heat required to raise or lower the temperature of one pound of water by one degree Fahrenheit. BTU/HR British Thermal Units per Hour. The heat transfer rate of HVAC equipment is measured in BTU/hr. Refer to BTU for more details. CAPACITY Usually measured in BTUs or tons, capacity refers to an air conditioning or heating unit’s ability to cool or heat a space. COP Coefficient of Performance. The COP rates a heat pump’s ability to efficiently use electricity. Note that with the M1 changes, this metric is not changing, but the minimum efficiency levels are increasing from the DOE 2018 standard. DATE OF INSTALLATION Under the 2023 requirements, compliance to regional standards is based on the date of installation, as opposed to the date of manufacture for the national deadline. Refer to National / North Region and Regional Standards for more details. DATE OF MANUFACTURE Under the 2023 requirements, compliance to the national deadline is based on the equipment date of manufacture. This differs from regions that are superseded by a regional standard, where compliance is based on the date of installation. Refer to Regional Standards, Southeast Region and Southwest Region for more details. DECARBONIZATION The process of cutting our dependence on resources that produce high levels of carbon emissions and greenhouse gases. DOE Department of Energy. The DOE is a federal agency that sets the standards for efficiency throughout the HVAC industry and monitors the consumption of energy sources. EER2 The updated metric for Energy Efficiency Ratio, formerly known as EER. The ratio of the cooling capacity of the air conditioner in BTUs per hour to the total electrical input in watts. This measure is determined by comparing test units to the AHRI specifications. EFFICIENCY A general term used to describe how effectively an HVAC system converts incoming energy to outgoing energy. The higher the number, the more efficient the unit, and the lower the operating costs. EPA Environmental Protection Agency GHG Greenhouse gas. A classification for types of gas that trap heat in the atmosphere. GWP Global Warming Potential. GWP measures how much energy the emissions of 1 ton of a gas will absorb over a given period, relative to the emissions of 1 ton of carbon dioxide (CO₂). The larger the GWP, the more a given gas will warm the earth compared to CO₂ over that same time. HFC Hydrofluorocarbon. HFC refrigerants are greenhouse gases commonly used by federal agencies in a variety of applications, including HVAC. IEER Integrated Energy Efficiency Ratio. A rating that is used for split systems and measures the efficiency of the unit under a range of circumstances and temperatures. Note that with the M1 changes, this metric is not changing, but the minimum efficiency levels are increasing from the DOE 2018 standard. HP Heat pump HSPF2 The updated metric for Heating Seasonal Performance Factor, formerly known as HSPF. It measures the efficiency of the heating portion of a heat pump. HVAC Heating, Ventilating and Air Conditioning. HVAC, which can also be stylized as HVACR to include refrigerant, is used to refer to the industry at large, particularly dealers of heating and air conditioning equipment. M1 The new DOE test procedure to determine product efficiency ratings. Also referred to as Appendix M1. The M1 test method is replacing the previous Appendix M in the Code of Federal Regulations. NATE North American Technician Excellence. NATE is the nation’s largest nonprofit certification organization for HVACR technicians. NATIONAL / NORTH REGION Regarding the 2023 testing and efficiency standards, the North region adheres to national standards for split and packaged air conditioners. Compliance is based on the date of manufacture and applies nationally unless superseded by regional standards in the Southeast and Southwest. For split and packaged heat pumps, the national standards apply across all regions. PACKAGED UNIT Equipment in which all heating and cooling components are in one cabinet. It is installed either beside or on top of a home or business. R-410A A popular HFC refrigerant that is scheduled for elimination from all new systems in 2023. REFRIGERANT The liquid used to absorb and transfer heat from one part of the HVAC system to another. REFRIGERANT LINES Copper lines that transfer the refrigerant between the outdoor unit and the indoor unit. REGIONAL STANDARDS The 2023 requirements apply nationally unless superseded by a regional standard. Regional standards apply in the Southeast and Southwest, and while the national deadline is based on equipment date of manufacture, compliance to the regional standards is based on the date of installation. Refer to Date of Installation, Date of Manufacture, Southeast Region and Southwest Region for more details. SEER2 The updated metric for Seasonal Energy Efficiency Rating, formerly known as SEER. It is used to express the efficiency of an air conditioning unit or a heat pump in cooling mode. The higher the SEER2 rating, the more efficient the unit. SOUTHEAST REGION For the 2023 testing and efficiency standards, states in this region supersede the federal minimum for split air conditioners, and compliance is based on the date of installation. Applies to the following states: Alabama, Arkansas, Delaware, Florida, Georgia, Hawaii, Kentucky, Louisiana, Maryland, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, Virginia, and the District of Columbia, U.S. Territories. Refer to Regional Standards for more details. SOUTHWEST REGION For the 2023 testing and efficiency standards, states in this region supersede the federal minimum for split and packaged air conditioners, and compliance is based on the date of installation. Applies to the following states: Arizona, California, Nevada and New Mexico. Refer to Regional Standards for more details. SPLIT SYSTEM An HVAC system that uses an indoor and an outdoor component to deliver comfortable air. TON Not related to the weight of the unit, a ton is 12,000 BTUs. A typical home cooling/heating system uses heat pumps or air conditioners with a capacity of between 1.5 and 5 tons. Refer to BTU for more details. ZONE/ZONING A home may be divided into several different areas, or zones, to better control the temperature. The process of dividing a home into different zones is called zoning.