Air Handler: The portion of a central air conditioning or heat pump system that moves heated or cooled air throughout a home’s ductwork. In some systems, a furnace handles this function.
Annual Fuel Utilization Efficiency (AFUE): A measure of a gas furnace’s efficiency in converting fuel to energy the higher the rating, the more efficient the unit. For example: A rating of 90 means that approximately 90% of the fuel is used to provide warmth to your home, while the remaining 10 percent escapes as exhaust.
Balance Point: An outdoor temperature – usually between 30°F to 45°F – at which a heat pump’s output exactly equals the heating needs of the house. Below the balance point, supplementary electric resistance heat is needed to maintain indoor comfort.
British Thermal Unit (BTU): This is the quantity of heat required to raise the temperature of 1 lb. of water 1°F at 39.2°F. BTUH stands for British Thermal Unit Per Hour — this establishes a time reference to Btu input or output rates. For your home, it represents the measure of heat given off when fuel is burned for heating or the measure of heat extracted from your home for cooling.
Blower: Component of your furnace or air handler that moves conditioned air through your duct system into your home. Blower is made up of a motor, wheel and a specially designed housing.
CFM: A standard of airflow measurement. Cubic feet per minute. Refers to the volume of air. A typical system produces 400 CFM per ton of air conditioning.
Capacity: The output or producing ability of a piece of cooling or heating equipment. Cooling and heating capacities are referred to on BTUs.
Compressor: The heart of an air conditioning or heat pump system. It is part of the outdoor unit The compressor maintains adequate pressure to cause refrigerant to flow in sufficient quantities to meet the cooling requirements of the system
Condensation: Water that condenses on an object such as the evaporator coil.
Condensor Coil/Outdoor Coil: Located in the outdoor unit, the coil dissipates heat from the refrigerant, changing the refrigerant from vapor to liquid. In a heat pump system, it absorbs heat from the outdoors.
Condensing Unit: Refers to the outdoor unit of a split system.
Damper: A device that is located in ductwork to control airflow. There are basically two types of dampers: manual and motorized. A manual damper generally fits inside of a duct. By rotating a handle located outside of the duct a technician can adjust the air flow to regulate airflow of a particular area or room. A motorized damper is generally used in a zoned system to automatically deliver conditioned air to specific rooms or zones.
Defrost Cycle: A special mode for a heat pump when operating in the heating mode. During normal heating season a heat pump’s outdoor coil will form a light frost. Which at a predetermined time and temperature the heat pump will switch into a defrost cycle. This stops the outdoor fan and reverses the refrigerant flow into cooling mode using the hot discharge gas to melt away and evaporate any moisture. During this cycle the outdoor unit will bring on any heat strips to compensate for the cold blow of the cooling mode.
Dew Point: Temperature at which vapor (at 100 percent humidity) begins to condense and deposit as liquid.
Ductwork: The delivery system through which conditioned air from the equipment is brought to where it’s needed. Ductwork is made of sheet metal, fiberglass, or flexible plastic, and can be round or rectangular in shape.
Dual Fuel: When a heat pump is installed in conjunction with a fossil fuel furnace. This system takes advantage of using the most economical fuel based on the outdoor temperature and the balance point of your home. Dual fuel systems can be configured from many combination of split system equipment and some package unit models are available.
Energy Efficiency Ratio Efficiency (EER): The rate at which a furnace maximizes fuel use. This rate is numerically described as a ratio called AFUE. High efficiency furnaces will be rated 85 to 95% AFUE.
Emergency Heat: Used on most heat pump thermostats. When switched to emergency heat, thermostat disables the heat pump and operates the heat strips like a standard electric furnace. Should only be used when outdoor side of the heat pump has malfunctioned.
Evaporator Coil/Indoor Coil: The other half of your air conditioning system which is located inside your home. In the indoor unit In the evaporator, refrigerant evaporates and absorbs heat from indoor air as it passes over the coil. Coils are most commonly constructed of copper tubing with aluminum plate fins.
Gas Furnace Heat Exchanger: The heat exchanger is located in the furnace and transfers heat to the surrounding air, which is then pumped throughout your home.
Heat Strip: A component that consist of a resistant material that produces heat when electricity flows through it. Commonly used with air to air HEAT Pumps for auxiliary, supplementary or emergency heat.
HSPF: Heating Seasonal Performance Factor and measures heat pump efficiency. The higher the HSPF, the greater the energy economy.
Output: Capacity of a furnace or air conditioner in BTU’s. Example- A gas furnace might have 100,000 BTUH of gas input but only produce 80,000 BTU’s of output.
Package System/Unit: A heating and cooling system where all components are located in one unit. A package unit is typically installed either beside, on top of the home.
Pressure Drop: The decrease in pressure due to friction of a fluid or vapor as it passes through a tube or duct or/and lift.
Refrigerant: is a compound used in a heating or cooling cycle that undergoes a phase change from a gas to a liquid and back. Most residential air conditioning systems contain R-22 and R-410 refrigerant.
Refrigerant Lines: Used on any type of split air conditioning or heat pump system consisting of two copper lines connecting the outdoor unit and the indoor unit.
Relative Humidity: The percentage of water vapor present in a given quantity air compared to the amount it can hold at its temperature.
R-Value: Is the thermal resistance of a given thickness of insulating material.
Seasonal Energy Efficiency Ratio (SEER): A rating that measures the cooling efficiency of a heat pump or air conditioner. The higher the SEER, the more efficient the unit and the greater the energy economy. The minimum set by the Department of Energy is 13 SEER.
Split System: Refers to a air conditioning system configuration consisting of components in two locations. Common examples include an outside unit, such as an air conditioner or heat pump and an indoor unit, such as a furnace and coil. Split systems must be matched for optimum efficiency.
Thermostat: A temperature control device, typically found on a wall inside your home that consists of a series of sensors and relays that monitor and control the functions of a heating and cooling system. A wide selection are available from simple mercury switch to electronic programmable thermostats allow you to program different levels of comfort for different times of the day.
Ton: A unit of measurement used for determining cooling capacity. One ton is the equivalent of 12,000 BTUs per hour.
Two-stage or Speed: Commonly refers to a special type of furnace, air conditioner or heat pump that can reduce its capacity when the full capacity of the equipment is not required. By doing so it can improve comfort and reduce utility bills.
Two-stage Variable: The furnace part is the same as a Two-Stage, the difference is in the blower motor. In a Single-Stage, if you want your fan on for circulation, that fan is on high. It is the only option it has. Not only is that hard on the utility bill, but a fan on high means the warm air is moving fast, warm air moving fast is a cool breeze. In a Variable, the fan turns over slowly to maintain air circulation while being easy on the utility bill. By switching its blower fan from a/c current to d/c current, it only draws 1/10 the electricity.
Vapor Barrier: A material designed to stop or reduce the flow of moist air from an unconditioned environment to a conditioned area. Used primarily in conjunction with insulating materials to reduce infiltration. Also used in crawl spaces to stop ground moisture from escaping.
Variable Speed: Commonly refers to an ICM blower motor in an air handler. Can also describe heating or air conditioning equipment that can adjust its output capacity in small increments.
Velocity: The speed at which air travels through a duct or register. Measured in Feet Per Minute, “FPM”.
Ventilation: Outdoor air that is introduced into the conditioned space through HVAC equipment in a controlled manner. Outside air can be required to replace air used during combustion of fossil fuel appliances, dilution of odors and gases or to replace air removed by exhaust fans in kitchens, bathrooms and laundry rooms.
Zoning: A system in which living areas are divided into separate spaces and each space’s heating/air conditioning is controlled independently. This can be accomplished by using either multiple independent systems, or a single system using electronic controls and motorized dampers.
