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A Guide to Heating and Cooling Acronyms

Buying an air conditioner can seem intimidating at first. Most people know that cost alone cannot be used to decide because one of the biggest determining factors in cost is the size of the unit and the size needed depends on the size of the area to be covered. Once the appropriate size is determined, the challenge then becomes to determine which unit provides the best or most cost effective options. During this step, consumers may be bombarded with acronyms, but the acronyms should not cause anxiety; each one is actually a specific yet simple to understand measure that makes side by side comparison across brands easy.


SEER stands for Seasonal Energy Efficiency Ratio. It measures the unit's efficiency over an entire cooling season and is the ratio of total BTUs used to watt-hours. The higher the rating, the lower the electric bill will be. A 13 SEER rating minimum is required by law for new units in the United States a rating of 14 is required to be Energy Star certified.


EER stands for Energy Efficiency Ratio. It is calculated slightly differently, focusing more on peak operation, and measures the cooling capacity in BTU per hour for a given number of watts. A higher EER means a more energy efficient unit.


MERV stands for Minimum Efficiency Reporting Value. It measures the effectiveness of air filters and shows the minimum particle size that can be expected to be captured by a filter. Most residential HVAC units have a rating of five to eight. Hospitals typically use a filter with a rating of 13 or higher. For typical HVAC applications, there is little noticeable difference between a rating of seven and higher ratings.


AFUE stands for Annual Fuel Utilization Efficiency. It compares the heat energy output against the energy actually used by the unit to generate the heat. If the rating is 80%, 80% of energy goes towards heating and 20% is consumed by the unit's operation, leaks, chimneys, etc. Electric units are usually at or near a rating of 100%, however high electricity costs often make fossil fuel powered units a more economical choice. For fossil fuel based units, the minimum rating varies from 75% to 90% based on type and location and energy efficient units typically have ratings of 90% or better.


HSPF stands for Heating Seasonal Performance Factor. It measures the efficiency of heat pumps during heating season and is the ratio of BTUs used during the heating season to the electricity consumed in watts. A higher rating means a more energy efficient unit. The minimum rating for new units is 7.7. While a higher HSPF is better, be careful if it will require sacrificing cooling efficiency; check energy bills for heating and cooling seasons to determine how much weight to give each factor.

Energy Star

Energy Star is a program created and run by the Environmental Protection Agency to help reduce greenhouse gas emissions and allow consumers to save money at the same time. This is achieved by requiring a higher level of energy efficiency than the legal minimum for inclusion into the program. For HVAC systems, the system must be at least 10% more efficient than the minimum to receive the label. The product must also not sacrifice features in order to increase efficiency and any increase in purchase price must be recoverable in the form of lower energy bills within a reasonable period of time.

Air Conditioner vs. Heat Pump vs. Furnace

In technical terms, an air conditioner is an HVAC unit that provides cooling only. It can take many forms such as central, window, portable, or ductless. Permanently installed systems are typically found in colder climates in buildings that have separate heating systems. This is because the increased energy efficiency of a single purpose system versus a combined heating and cooling system does not outweigh the cost of installing a separate heating system in warmer areas.

A heat pump is a combined heating and cooling unit, usually either as a central, duct based system or as a ductless system. Because of its dual purpose, the installation cost is lower, but some energy efficiency is lost. These are typically installed in mild or warm climates that do not see long periods of freezing temperatures.

Furnaces are the typical method of providing heat in cold climates. They are generally fossil fuel based, usually gas. Heat is produced centrally and distributed throughout the building via water or steam in a radiator system or via air in a fan or duct system. Despite high gas prices, they are generally cheaper to operate than electric units when the weather requires the heat to be turned on for long periods of time.

Factory Authorized Dealer

A factory authorized dealer works closely with the manufacturer of the HVAC system. The dealer's employees are often directly trained by the manufacturer, ensuring they fully understand the products they are selling, can provide expert installation, and will competently perform any repairs. Factory authorized dealers, like those found on, are also held to high standards by the manufacturers who share their name with the dealer. In addition to requiring full compliance with local laws and licensing requirements, the manufacturers also monitor the customer service provided by the dealers and require that any parts used in installations or repairs are certified by the factory.

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