Air Conditioning and Heating

AFUE - This is a measure of a furnaces heating efficiency. AFUE stands for Annual Fuel Utilization Efficiency. The higher the rating, the more efficient the unit. A rating of 80 would indicate that 80% of the fuel being burned would be utilized in putting warmth in your home. The other 20% would be lost as exhaust.

Air Filter - Designed to remove dust, dirt and sometimes pollen from the air before it passes through the evaporator coil. The air filter protects the evaporator coil and blower from being clogged with dirt. It is important to regularly change the air filter to help prevent expensive air conditioning repairs. Once the evaporator coil becomes dirty, air will not properly flow through the coil. Without air flow, heat cannot be transferred.

Air Handler - A unit that conditions and circulates the air in part of a heating, ventilation, and air conditioning system. Usually an air handler contains a blower and heating and/or cooling elements.

Auxiliary Drain Line - See Secondary Drain Line

Balance Point - The outdoor temperature point at which a heat pumps output equals the heating needs of the space being heated.

BTU - This is a measure of the amount of heat it takes to raise one pound of water one degree Fahrenheit. BTU stands for British Thermal Unit. For heating, when fuel is combusted, it is measured in BTU's. Burning a wooden match is approximately equal to 1 BTU. For cooling, it is a measure of heat being removed from your house. So both air conditioning and heating equipment can be measured in BTU's.

BTUH - This is a measure of BTU's per Hour.

Capacitor - An electrical circuit element used to store an electrical charge for short periods of time. A capacitor consists basically of two metallic insulated plates separated by a dielectric.

Capacity - The output of air conditioning or heating equipment. For a heating system, the capacity is expressed in BTR's. For cooling, capacity is expressed in tons. One ton of air conditioning is the ability of the equipment to move 12,000 BTU's per hour.

Carbon Monoxide - An odorless, colorless, highly poisonous gas that is formed by the incomplete combustion of a carbon based material such as natural gas or gasoline.

CFM - This is a measure of air flow. CFM stands for Cubic Feet per Minute.

Charging a System - Add refrigerant to a system. A set of gauges is used to determine the proper amount of refrigerant.

Coil - Designed to transfer heat in an air conditioning system. The evaporator coil transfers heat by a refrigerant from the house and moves it outside via the condenser coil.

Compressor - Located inside the condenser in a residential split air conditioning system, the compressor compresses gas refrigerant pushing the molecules tighter together. The resulting hotter gas is then cooled in the condenser coils where it returns to a liquid. The compressor circulates the refrigerant in a loop.

Condensation - The process by which a gas or vapor forms a liquid. Cold air cannot hold as much moisture as warm air, therefore when warm air passes through the cold evaporator coils condensation forms.

Condenser - The large unit that is located outside the house in a split air conditioning system. The condenser consists of condenser coils, a compressor, a fan and fan motor, and electrical components.

Condenser Coil - A series of coils and aluminum fins designed to transfer heat. The coils inside the condenser contain hot compressed gas refrigerant. By use of a fan, air is drawn through the coils, expelling the heat and turning the gas refrigerant back into a liquid.

Contactor - A relay or electrically controlled switch used for switching a power or control circuit. The controlling circuit of a contactor has a much lower power level than the switched circuit.

Damper - A movable plate that is installed in a duct system to control air flow. It can be used to reduce air flow in a room or balance the air flow in a duct system. A damper system is also used in zoning.

Diffuser - A device used to slow the velocity of moving air.

Digital Thermostat - Temperature changes are recorded by thermal resistors and they have no moving parts.

Digital Programmable Thermostat - A thermostat with a built in memory the can be programmed to heat or cool, at requested temperatures, at different times of the day.

Disconnect - A box typically mounted on the side of a house near the condenser which allows the power to be shut off to the unit.

Drain Line - Pipe used to drain condensation away from the evaporator.

Drip Pan - See emergency drain pan.

Ductwork - A system of ducts that channel air flow from a heating or cooling system. Duct-work includes hard pipe, flex duct, vents etc.

EER - This is a measure of how efficiently a product will perform. EER stands for Energy Efficiency Ratio. It is expressed in BTUH/watts.

Elecrtonic Air Filter - The filter used in an electronic air cleaner. An electric charge is placed on air born particles which allows the filter to collect microscopic particles such as dust, smoke, pollen and bacteria. The filters can be removed, washed and reused.

Emergency Drain - See Secondary Drain

Energy Star - A joint venture of the U.S. Department of Energy and the U.S. Environmental Protection Agency. The goal is to save money and Protect the environment through energy efficient products and services.

Evaporator Coil - A series of coils and fins, within a housing, designed to transfer heat from the house. Liquid refrigerant is dispersed within the coils, boils into a gas, and the gas carries the heat to the compressor. This heat is then expelled in the condenser coils. Moisture in the form of condensation also is removed from the air by the evaporator coil, dehumidifying the air within the house. The collected moisture is sent down a drain.

Freon - A refrigerant trade marked by Dupont Corporation. It is considered harmful to the ozone, and is be replaced by other refrigerant alternatives. Production of air conditioning equipment that used R-22 Freon ceased January 1, 2010. Production of R-22 freon will cease in 2020.

Furnace - A unit designed to produce heat by combustion within an enclosure.

Grille - A fixed covering through which air passes.

Heat Pump - Provides both air conditioning and heating by means of a reversing valve which essentially allows the air conditioner to run in reverse. Heat pumps move heat, they don't create heat. In the air conditioning mode, a heat pump moves heat out of the house to cool the house. In the heat mode, heat pumps move heat from the outside air to inside the house. The is heat in air down to absolute zero which is 460 degrees F.

Heat Strips - Electric heating coils located inside the air handler.

High Limit Switch - A safety device that monitors the temperature inside a furnace. A "high limit switch" will turn off the furnace if the temperature gets too high.

Hot Surface Ignitor - Used in modern furnaces to light the gas. Electricity passes through a "hot surface ignitor" causing it to glow red.

HSPF - This is a measure of a heat pumps heating efficiency. HSPF stands for Heating Seasonal Performance Factor.

Humidifier - A humidifier adds water vapor to the air. In the cold of winter, higher humidity makes a house more comfortable because water holds heat and also slows the bodies natural cooling abilities.

Humidistat - A device that controls relative humidity. It measures humidity and can control either humidifying or dehumidifying equipment.

HVAC - Heating, ventilation, and air conditioning.

Indoor Coil - See evaporator coil.

Intermittent Pilot Ignition - An electronic system which uses an electrode to ignite the pilot gas. It is termed intermittent because the pilot is only lit when the main burner is operating. Designed to save fuel.

Liquid Line - The smaller of the two refrigerant lines which carries liquid refrigerant from the condenser to the inside unit (evaporator coil).

Mechanical Thermostat - Old style thermostats commonly using two coils of metat and a vial of mercury.

MERV - This is a measure of air filter efficiency. MERV stands for Minimum Efficiency Reporting Value. The higher the MERV value the more efficient the filter. The MERV scale ranges from 1 to 16.

Outside Unit - See condenser.

Overcharged - There is too much refrigerant in the air conditioning system.

Package Unit - The air conditioning and heating components are located outside in one piece of equipment. They are "packaged" together. Most commonly used in commercial businesses, they usually are located on the roof. or on the ground beside the building.

Pad - The condenser commonly sits on a pad, which is concrete slab or a slab built with light weight materials.

Payback analysis - Determines the number of years required for the energy savings to pay back the cost of the equipment.

Puron - This is a brand name for the refrigerant 410A, which is considered to be an environmentally sound alternative to the ozone depleting refrigerant Freon, (R-22). Puron was developed by Allied Signal and in 1996 Carrier Corp was the first to manufacture air conditioning equipment that used it. Puron contains no Chlorine.

R-22 Refrigerant - See Freon.

Reciprocating Compressor - A type of air conditioning compressor that compresses refrigerant using a piston.

Refrigerant - A liquid capable of vaporizing at a low temperature used in mechanical refrigeration.

Refrigerant Lines - The copper lines that connect the outside unit (condenser) to the inside unit (evaporator coil). The lines are termed suction and liquid lines.

Register - A grille equipped with a damper.

Scroll Compressor - A type of compressor that compresses refrigerant using a circular or spiraling motion. A scroll compressor is generally quieter and more energy efficient.

Secondary Drain Line - Emergency drain line that goes from the emergency drain pan (drip pan) to the outside. When water is seen coming out the secondary drain line there is a problem that needs attention. Secondary drain lines are commonly PVC that extends out of a roof eve.

SEER - This is a measure of an air conditioners cooling efficiency. SEER stands for Seasonal Energy Efficiency Rating. The higher the number, the more efficient the equipment.

Split System - Components are located both outside and inside the house. The condenser is the large unit outside the house. The air handler(electric) or evaporator coil and furnace(gas) would be located inside the house. Split systems are most commonly used in residential air conditioning.

Suction line - The larger of the two refrigerant lines which carries refrigerant in a gaseous state from the inside unit (evaporator coil) to the outside air conditioning unit (condenser). The gas refrigerant enters the compressor where it is compressed tightly together. It is then pumped through the condenser coils where it turns back to a liquid.

Supplemental Heat - Emergency or auxiliary heat that supplements a heat pump. Activated when needed to keep a heat pump heating at above its balance point.

Thermostat - A device that monitors temperatures and activates HVAC equipment to maintain a desired preset temperature.

Thermostatic Expansion Valve - A metering device that controls the amount of liquid refrigerant that enters the evaporator. Commonly called a TXV.

Ton - This is a measure used to determine cooling capacity. One ton equals 12,000 BTU's per hour.

Undercharged - There is not enough refrigerant in the air conditioning system.

Whip - The high voltage electrical connection used typically between the "disconnect box" and the condenser.

Zoning - A energy efficient way to cool and heat a home by using dampers to control air flow in specified zones of a house. The equipment is controlled by programmable thermostats.