Decoding Common HVAC Terminology

September 21, 2020

The HVAC industry uses many terms that may be unfamiliar or even confusing to the layman but are important for homeowners to recognize and understand. With that in mind, let us look at a dozen of these terms that we believe are important for every HVAC industry customer to appreciate.

North American Technician Excellence

NATE stands for North American Technician Excellence. This is an important acronym because you will often see HVAC companies promote that they have NATE-certified technicians on staff. NATE is a nonprofit certification organization for the HVACR industry—the R stands for refrigeration. The value of a NATE-certification is knowing that a professional is highly skilled. To get certified, one must be trained in the latest technologies and methods, passing rigorous exams and being recertified on a regular basis.

Air Conditioning Contractors of America

HVAC companies often promote that they are members in good standing of the Air Conditioning Contractors of America. The ACCA is a trade association for the HVACR industry. It helps to establish standards and codes, including assisting state and local governments in modernize building codes. It accredits and re-accredits HVAC companies in addition to providing technician training.

Seasonal Energy Efficiency Ratio

The SEER rating is a metric established by the Air Conditioning, Heating and Refrigeration Institute. Its European counterpart is known as ESEER. SEER is a measure of how energy efficient an air conditioner is. It was established so that federal and state governments could set standards but also so consumers could easily compare one AC unit to another. The current federal SEER minimum is 13 or 14 depending on your region. Opting for a better SEER rating can provide substantial energy savings, but choosing the ideal AC unit for a home is more complex than simply opting for the highest SEER rating available.

Annual Fuel Utilization Efficiency

AFUE is a thermal efficiency metric intended to gauge real-life heating performance over a season rather than capture ideal efficiency in a lab. A furnace with an AFUE rating of 90% converts 90% of the fuel it consumes into usable heat. Although it is quite different in the specifics, you can think of AFUE as the equivalent of SEER for furnaces. The government uses it to establish standards, and you can use it to compare the energy efficiency of one furnace to another.

Energy Efficiency Ratio

EER is a rating of how efficient an AC unit is at a particular temperature. Think of it as a snapshot of a moment in time. SEER encompasses EER but extrapolates that data over an entire season. Window AC units are still rated with EER rather than SEER. This is because of how window AC units tend to be used—running over long periods—which makes EER a more accurate gauge of their performance.

Heating Seasonal Performance Factor

HSPF is the SEER equivalent for heat pumps. Conventional heat pumps often have an HPSF between seven and nine. The newer geothermal heat pumps can have a rating of 10 or higher.

Minimum Efficiency Reporting Value

Anyone who has ever purchased an air filter for home use has probably encountered the MERV rating, which measures the effectiveness of a filter media. A filter with a higher MERV can trap smaller air particles and thus restricts airflow more. Restricted airflow is the reason you should purchase filters within the MERV range for your unit. A filter with too high a MERV could actually lead to unit damage.

Relative Humidity

Relative humidity—often abbreviated RH—is a measure of how saturated air is with moisture. Warmer air can be more saturated than cooler air. The reason RH is important to home heating and cooling is that it affects how you perceive temperature. A higher humidity level can actually be beneficial during winter since it lets you keep the home at a lower temperature. However, this will not be advantageous during summer. The ideal RH in a home is about 40% to 50%. Too high can contribute to mold growth whereas too low can irritate eyes, sinuses and your skin. Most HVAC systems involve some humidity control, but homes that need more can have a whole-house humidifier or dehumidifier installed.

Programmable and Smart Thermostats

Most homeowners appreciate that a programmable or smart thermostat is more sophisticated than a basic manual or digital thermostat in that you can set a temperature schedule. This allows you, for instance, to maintain a warmer home while at work and have the temperature automatically lowered before you return in the evening. Distinguishing between the terms programmable and smart is less clear, which may be because manufacturers are not consistent in their usage of these terms. The term smart can distinguish a product from a programmable unit in two ways. It can mean that the thermostat supports machine learning and can adjust your programming based on your usage. Smart could also mean that the product supports communication with other smart devices for the purposes of a smart home.

Heat Pump

Many people associate home heating with furnaces and, to a lesser extent, boilers. The term heat pump is foreign to many homeowners, and the reason for this is that heat pumps have traditionally only been practical in certain areas of the country. This is, however, changing as geothermal heating solutions become more affordable. A gas furnace generates heat by combusting gas. An electric furnace generates heat by moving air over a heated element. A heat pump, on the other hand, does not generate heat but rather transfers heat from outside the home to inside or vice versa, which means that a heat pump can warm a home during winter but also cool it during summer.


Mini-split systems provide both heating and cooling within a single unit. They also do not require a duct network to provide conditioned air to the home, which makes them a strong option for retrofitting older homes or in any scenario where ducts are not practical. These systems involve an indoor unit—the evaporator—and an outdoor unit—the condenser. Installing is generally simple and only requires a three-inch hole in the wall to allow for the linking of the outside and indoor units. The term multi-split refers to systems where a home has multiple evaporators all connected to a single condenser.

Zoned HVAC

Traditional central air systems deliver conditioned air equally throughout a home. Zoned HVAC—also known as an HVAC zoning system—involves two or more zones within a home that can be set to different temperatures. This is made possible through a variable-speed air handler that can adjust to different pressure requirements and dampers in the duct system that can redirect air throughout a home. The most common setup is to have an upstairs zone and a downstairs zone.

Your Local HVAC Experts

C & C Heating & Air Conditioning is proud to be a leading HVAC company serving Roseville, Macomb County and beyond. Our business was established in 1948, which means we now have more than 70 years of experience meeting the heating and cooling needs of area residents. We offer a wide range of air conditioning and heating services, including installation, replacement, maintenance and repair.

Call C & C Heating & Air Conditioning today to learn more about these services and schedule an appointment.

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