At Patriot Heating and Cooling, we understand that navigating the world of HVAC (Heating, Ventilation, and Air Conditioning) can be complex. Whether you’re a homeowner looking to optimize your system’s efficiency, a business owner managing climate control, or simply curious about the components that keep your environment comfortable, our comprehensive HVAC glossary is here to help. This HVAC glossary is designed to demystify the technical jargon and provide clear, concise definitions of key terms you’ll encounter in the HVAC industry.
Enjoy Our HVAC Glossary:
Air Handler Unit (AHU)
An Air Handler Unit is a central unit consisting of a blower, heating or cooling elements, filter racks or chambers, sound attenuators, and dampers. Its purpose is to condition and circulate air as part of an HVAC system. AHUs are connected to ductwork that distributes the conditioned air through the building and returns it to the AHU.
Heat Exchanger
A heat exchanger is a device that transfers heat between two or more fluids (liquids or gases) without them mixing. In HVAC systems, it is used to transfer heat from the combustion gases to the air or water that is being heated for distribution in the space. This process is crucial for efficient heating and cooling operations.
Refrigerant
Refrigerant is a substance, typically a fluid, used in air conditioning systems to absorb heat from the environment and provide cooling when it changes state from a gas to a liquid and back. Common refrigerants include R-22, R-410A, and R-134a. The choice of refrigerant can affect the efficiency and environmental impact of the HVAC system.
Thermostat
A thermostat is a device that senses the temperature of a system and regulates the system to maintain the temperature at a desired setpoint. It works by switching heating or cooling devices on or off to maintain the set temperature. Modern thermostats often include programmable and smart features for increased energy efficiency.
Ductwork
Ductwork refers to the system of ducts used to transport air from HVAC units to various parts of a building. It includes supply ducts that deliver conditioned air and return ducts that bring air back to the system for reconditioning. Properly designed and sealed ductwork is critical for efficient HVAC operation and indoor air quality.
Heat Pump
A heat pump is a device that transfers heat energy from a source to a heat sink. In HVAC applications, it can be used for both heating and cooling. In heating mode, it extracts heat from the outside air or ground and transfers it indoors. In cooling mode, it reverses the process, extracting heat from indoors and releasing it outside.
Indoor Air Quality (IAQ)
Indoor Air Quality refers to the air quality within and around buildings and structures, especially as it relates to the health and comfort of building occupants. IAQ is influenced by contaminants such as mold, bacteria, dust, and chemicals, as well as proper ventilation and filtration systems in HVAC design.
Variable Air Volume (VAV) System
A Variable Air Volume system is an HVAC system that provides variable airflow at a constant temperature. VAV systems are designed to provide precise temperature control, reduce energy consumption, and improve occupant comfort by varying the airflow to different zones or spaces within a building based on the heating or cooling load.
Chiller
A chiller is a machine that removes heat from a liquid via a vapor-compression or absorption refrigeration cycle. This liquid can then be circulated through a heat exchanger to cool air or equipment as needed. Chillers are a critical component of central air conditioning systems in large buildings and industrial processes.
Boiler
A boiler is a closed vessel in which water or another fluid is heated. The fluid does not necessarily boil; the heated or vaporized fluid exits the boiler for use in various processes or heating applications, including space heating, power generation, and water heating. Boilers can run on various energy sources, including natural gas, oil, and electricity.
Evaporator Coil
The evaporator coil is a crucial component of an air conditioning system. Located inside the air handler or attached to the furnace, it absorbs heat from the air in your home. The refrigerant in the evaporator coil changes from a liquid to a gas, effectively cooling the air that passes over the coil before it’s distributed through the home.
Condenser Coil
The condenser coil is located in the outdoor unit of an air conditioning system. It receives the high-pressure, high-temperature refrigerant from the compressor. The refrigerant releases its heat to the surrounding outdoor air as it condenses back into a liquid state. This process is essential for the continuous cycle of refrigeration and cooling.
Compressor
The compressor is the heart of an HVAC system’s refrigeration cycle. It pressurizes the refrigerant, increasing its temperature and preparing it for heat exchange in the condenser coil. The compressor’s role is vital for the refrigerant to circulate through the system efficiently, enabling the cooling or heating process.
Expansion Valve
The expansion valve is a key component in an HVAC system that regulates the flow of refrigerant into the evaporator. It allows the refrigerant to expand, lowering its pressure and temperature before it enters the evaporator coil. This process is crucial for the refrigerant to absorb heat effectively and provide cooling.
BTU (British Thermal Unit)
A British Thermal Unit is a unit of heat energy. It is defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. In HVAC terms, BTUs are used to measure the heating or cooling capacity of a system, helping to size equipment appropriately for the space it will serve.
SEER (Seasonal Energy Efficiency Ratio)
SEER is a metric used to measure the efficiency of air conditioners and heat pumps over a typical cooling season. It is calculated by dividing the cooling output (in BTUs) by the total electrical energy input (in watt-hours) over the same period. Higher SEER ratings indicate more energy-efficient systems.
HSPF (Heating Seasonal Performance Factor)
HSPF is a measure of the efficiency of heat pumps during the heating season. It is calculated by dividing the total heating output (in BTUs) by the total electrical energy input (in watt-hours). Higher HSPF values indicate greater efficiency, making it an important factor in selecting heat pumps for energy-conscious consumers.
AFUE (Annual Fuel Utilization Efficiency)
AFUE is a measure of a furnace’s efficiency in converting fuel to heat over a typical year. It is expressed as a percentage, representing the fraction of fuel energy that is converted into useful heat. Higher AFUE ratings mean greater efficiency and lower fuel costs for homeowners.
ERV (Energy Recovery Ventilator)
An Energy Recovery Ventilator is a device that improves indoor air quality and reduces energy consumption by exchanging stale indoor air with fresh outdoor air while transferring heat and moisture between the airstreams. This process helps maintain comfortable indoor humidity levels and reduces the load on the HVAC system.
HRV (Heat Recovery Ventilator)
A Heat Recovery Ventilator is similar to an ERV but focuses on transferring heat between incoming and outgoing air streams without transferring moisture. HRVs are ideal for colder climates where controlling humidity levels is less critical, and the primary goal is to recover heat to reduce energy consumption.
Split System
A split system is an HVAC setup where components are divided between an indoor unit and an outdoor unit. Typically, the indoor unit contains the evaporator coil and air handler, while the outdoor unit houses the compressor and condenser coil. Split systems are common in residential and small commercial applications.
Packaged Unit
A packaged unit is an all-in-one HVAC system that contains all components—compressor, condenser, and evaporator—in a single outdoor unit. These systems are often used in commercial buildings or homes with limited indoor space for separate air handlers and furnace units.
Zoning System
A zoning system in HVAC allows for different areas or “zones” within a building to be heated or cooled independently. This is achieved through the use of dampers in the ductwork and individual thermostats for each zone, providing customized comfort and increased energy efficiency.
Ductless Mini-Split System
A ductless mini-split system is an HVAC solution that provides heating and cooling without the need for ductwork. It consists of an outdoor unit and one or more indoor units mounted on walls or ceilings. These systems are ideal for retrofitting older homes, room additions, or spaces where ductwork is impractical.
Hydronic Heating
Hydronic heating is a system that uses water or another liquid as a heat transfer medium. The heated fluid circulates through a network of pipes to radiators, baseboard heaters, or radiant floor systems, providing consistent and efficient heating. This method is known for its comfort and energy efficiency.
Radiant Heating
A humidifier is a device that adds moisture to the air to maintain optimal indoor humidity levels. It is particularly useful in dry climates or during winter months when indoor air can become excessively dry. Humidifiers can be standalone units or integrated into HVAC systems, helping to improve comfort and health.
We hope this HVAC glossary has been a valuable resource in enhancing your understanding of heating, ventilation, and air conditioning systems. At Patriot Heating and Cooling, our mission is to ensure you have the knowledge and tools necessary to make the best decisions for your comfort and efficiency needs. Note that this HVAC glossary is not a complete reference to all terms in the industry, but we will be updating it regularly with new terms.
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