An air handler, or air handling unit, is the indoor part of an air-conditioning or heat pump system. Air handlers work much like furnaces in that they efficiently move air throughout the home. The main difference is that the air handlers only circulate heat when paired with a heat pump.
BRITISH THERMAL UNIT (BTU) A British Thermal Unit (Btu) is a measurement of heat energy. One Btu is the amount of heat required to raise one pound of water by one degree Fahrenheit. Btus per hour (Btuh) is the benchmark used to estimate the capacity of a heating system, such as a gas furnace. Available in heating capacities ranging from 30,000 to 135,000 Btuh. A furnace with a lower Btuh range is typically made for a small multifamily home, single family home or a single floor in a 2-story home. Higher-capacity furnaces are made for larger single family homes, large single story homes, and light commercial applications.
Central air conditioning (or central A/C) is a system in which air is cooled at a central location and distributed to and from rooms by one or more fans and ductwork. The work of the air conditioner compressor is what makes the whole process of air conditioning possible. The compression of the refrigerant gas enables it to discharge heat out of the house, which is how the cool air is created.
The evaporator and condenser coils inside a central air conditioner or heat pump make it possible for these systems to complete the heat exchange process, which is the basis of refrigerated cooling and, in the case of heat pumps, heating. The coils form a loop and, even though they’re continuous, each has a different function.
COMPRESSOR an AC or heat pump compressor is the part of an outdoor air conditioner or heat pump that compresses and pumps refrigerant to meet household cooling requirements. The compressor in the air conditioner or heat pump circulates refrigerant. Refrigerant absorbs and releases heat as it travels between the indoor and outdoor units, helping to maintain a cool and comfortable indoor temperature. Single-stage and two-stage cooling compressors can work at either a single level of operation or two stages.
CONDENSER (or AC condenser) is the outdoor portion of an air conditioner or heat pump that either releases or collects heat, depending on the time of the year. Both split air conditioner and heat pump condensers are made of the same basic parts. The condenser cabinet contains the condenser coil, a compressor, a fan, and various controls. The condenser coil can be made of copper tubing with aluminum fins or all-aluminum tubing so heat can be rapidly transferred. The condenser fan is a vital component and circulates the air across the coil to facilitate heat transfer. The compressor is the heart of the system since it compresses the refrigerant and pumps it to a coil in the form of a hot gas. In air conditioners, the refrigerant is cooled at the condenser into a warm liquid, and passes through a pipe into the evaporator coil where it expands and cools. In heat pumps, the hot gas is pumped directly to the evaporator coil to provide heat.
Cubic Feet Per Minute (CFM) is a measurement of airflow volume, determined by how many cubic feet of air pass by a stationary point in one minute. Larger homes circulate more air (since there’s more space for it to move around), so they will have a higher CFM. Why is CFM important? Having an accurate estimate of your home’s CFM is key to choosing an HVAC system with the right capacity for your space and needs. Too much or too little airflow can negatively impact your system performance and even cause damage to its components.
The U.S. Department of Energy (DOE) is a federal agency responsible for monitoring the consumption of energy sources and setting industry efficiency standards for all heating and cooling units manufactured in the U.S. Since as much as half of the energy used in your home goes to heating and cooling,* it helps to consider products with high efficiency ratings.
Ductwork refers to the system of ducts (metal or synthetic tubes) used to transport air from heating, ventilation and air-conditioning (HVAC) equipment throughout your home. Properly installed and well-maintained air ducts are a key component of indoor air quality and home comfort.
The Energy Efficiency Ratio (EER) of an HVAC cooling device is the ratio of output cooling energy (in BTU) to input electrical energy (in watts) at a given operating point. EER is normally calculated with a 95 °F outside temperature and an inside (return air) temperature of 80 °F and 50% relative humidity.
ENERGY STAR® is a program of the U.S. Environmental Protection Agency (EPA) designed to help consumers and businesses save money by choosing energy-efficient products and technologies. Heating, ventilation and air-conditioning (HVAC) equipment with the ENERGY STAR® label meets or exceeds federal guidelines for energy-efficient performance.
The U.S. Environmental Protection Agency (EPA) is a federal agency that develops and enforces federal environmental regulations and oversees the nationwide ENERGY STAR® program. Simple ways to cut home energy costs and protect the environment Heating and cooling is often a home’s largest energy expense, so choosing an energy-efficient home comfort system not only helps conserve environmental resources, it also helps lower your utility bills.
An evaporator coil is the part of an air conditioner or heat pump that absorbs the heat from the air in your house. It is located inside the air handler or attached to the furnace. The evaporator and condenser coils inside a central air conditioner or heat pump make it possible for these systems to complete the heat exchange process, which is the basis of refrigerated cooling and, in the case of heat pumps, heating. The coils form a loop and, even though they’re continuous, each has a different function. The role of the evaporator coil located inside the blower compartment or air handler, the evaporator coil holds the chilled refrigerant that the compressor moves into it. As the air from the blower fan moves over the coil, the cold refrigerant removes the heat from your home’s air. The refrigerant becomes warmer and travels to the condenser coil outdoors. With a heat pump, the process reverses in the winter and the evaporator coil expels heat from the refrigerant into your home, instead of absorbing it and taking it outdoors. Most heat pumps have auxiliary heating elements that are part of the evaporator coil components to supply heat when temperatures fall below a certain point.
A fan coil unit (FCU) is a device that uses a coil and a fan to heat or cool a room without connecting to ductwork. Indoor air moves over the coil, which heats or cools the air before pushing it back out into the room. FCUs can be less expensive to install than ducted systems, and are available in ceiling, floor-mounted and freestanding configurations.
Gas Furnaces in a natural gas or propane furnace, a pilot light ignites the source gas, igniting burners inside a combustion chamber. The generated heat then enters a heat exchanger, transferring heat to the air and raising the temperature of a space to the level set by a thermostat.
A heat exchanger is a heating component inside furnaces that transfers heat to the surrounding air, which is then distributed throughout the home.
A heat pump is an HVAC unit that heats or cools by moving heat. During the winter, a heat pump draws heat from outdoor air and circulates it through a home's air ducts. In the summer, it reverses the process and removes heat from the house and releases it outdoors. Variable operation heat pumps can work at either a single level of operation or two stages of operation. Single-stage HVAC systems are still the most common systems used. A single-stage heat pump has only one level of heat or cold output.
HVAC is an acronym for heating, ventilation and air-conditioning systems. This includes products like furnaces, air handlers, packaged units, heat pumps, air conditioners and whole-home ventilators. The ductwork connected to these pieces of equipment is another component of HVAC, as well as, thermostats and other home comfort controls. A HVAC system, also called split system HVAC or a home comfort system, can also include indoor air quality (IAQ) products with capabilities that go beyond ventilation. Air cleaners or air purifiers, humidifiers, dehumidifiers and filtration systems are all products that can help remove allergy-aggravating contaminants from a home’s air.
A heating and cooling system that uses dampers in the duct work to regulate and redirect air to specific areas of the home. This allows for the creation of customized temperature zones throughout the home for increased comfort and efficiency.
The Minimum Efficiency Reporting Value (MERV) rating is used to rank the efficiency of air filters. Every air filter has holes that allow air and particles to pass through. The smaller the holes, the fewer particles that can pass through. Higher MERV ratings indicate smaller holes, and therefore a more efficient filter.
North American Technician Excellence (NATE) conducts rigorous, independent testing verifying the real-world knowledge and application of HVAC technicians and installers.
A programmable thermostat is a thermostat with the ability to adjust home heating and cooling equipment according to a your pre-set comfort schedule. A programmable thermostat could be set to maintain a home temperature of 72 degrees throughout the day, and 65 degrees through the night.
The old standard for residential air conditioners, now being phased out by the U.S. EPA. Companies offer dry-charged units for those who still have R-22 compatible systems.
A chlorine-free refrigerant that meets the U.S. EPA's newest, most stringent environmental guidelines
A chemical that produces a cooling effect while expanding or vaporizing. Most residential air-conditioning units contain the standard R-22 refrigerant, or freon.
A heating and cooling system that includes an indoor unit, outdoor unit and a thermostat.
A thermostat is a device that monitors the indoor temperature and automatically adjusts your heating or cooling system to maintain the desired level.
Unit of measurement for determining cooling capacity. One ton equals 12,000 Btuh.
A motor that operates at a wide range of speeds to precisely control the distribution of heated and cooled air throughout the home.
A ventilator is a device that replaces the stale, recirculated air inside your home with fresh, filtered outdoor air. An energy recovery ventilator (ERV) is ideal for warm and humid climates, since it cools and dehumidifies the incoming outdoor air. A heat recovery ventilator (HRV) is more appropriate for colder climates, as it transfers heat from recirculated air to the fresh incoming air.