AIR CONDITIONING:

To add heat or remove temperature and humidity in the form of condensation and promote clean air in a building.

B.T.U:

British Thermal Unit, the quantity of heat required to raise one pound of water one degree in Fahrenheit.

BOILER: A piece of heating equipment which is used to heat water to a hot water condition or a steam condition, depending on the type of system. This hot water or steam then circulates throughout a building into baseboards or radiators.

BAROMETRIC DRAFT REGULATOR:

A part of the flue in an oil furnace used to control the "STACK" temperature of the flue. It is usually a weighted device which allows air into the flue as the need is required.

BURNER:

A part in the furnace where gas is injected into the heat exchanger along with the correct amount of combustion air for proper ignition and burning of the gases. Yearly service of this part should be done by a professional service technician.

CAPACITOR:

An electric device consisting of two or more conducting plates separated from one another by an insulating material and used to store an electrical charge. There are RUN capacitors and START capacitors.

CIRCUIT BOARD:

A laminated electrical board, usually fitted with electronic components used in furnaces, boilers, air handlers and condensers to control most of the functions of the equipment. Some of these boards also have relays on them. To see a board click here See a Printed Circuit Board

COMBUSTION AIR:

The air that must be fed to the burners of a gas or oil fired furnace or package heat unit for safe combustion of the fuel. As an example: most basements will need combustion air "PIPES" to bring and return the correct amount of outside air into the furnace. Direct vent furnaces usually don't require this however. 
To see a combustion air duct installation click here.

COMPRESSOR:

A "PUMP" used in air conditioning systems and usually located in the CONDENSER to move a refrigerant through an EVAPORATOR and back to a CONDENSER. This compressor changes the temperature and state of the refrigerant if it is operating correctly. Located in the CONDENSER. This is the most expensive part of an air conditioning system to replace and should be checked yearly by a professional service technician.

CONDENSER:

The piece of equipment used to remove the heat that has already been removed from a building. Usually located at ground level, but can be mounted on a roof, but is almost always outdoors. There are some mostly older systems that have the condenser indoors and "DUCT" the unwanted heat outdoors.

CONDENSER COIL:

A series of aluminum or copper tubes with aluminum plates or spinney fins attached to them used to dissipate heat which the COMPRESSOR has removed from the building. Located in the CONDENSER.

CONDENSER MOTOR:

The motor which turns the condenser fan blade or wheel in the CONDENSER which removes heat from the CONDENSER COIL.

CONDENSATE PUMP:

A small pump used to pump the condensate water which was removed by the EVAPORATOR COIL.

CONTACTOR:

An electrical relay which controls the flow of electricity to different components in the system.

DISCONNECT BOX:

An electrical box used to shut off equipment for servicing. Some of these have fuses or circuit breakers in them.

DUCT BOARD:

A fiberglass sheet, usually used to to build plenums, trunks drops and sometimes ducts themselves in a typical building duct system.

DUCT TAPE:

Tape used to seal any air leaks in a system. They can be fabric or metal depending on the application.

DUCT WRAP:

An insulating fiberglass blanket wrapped around ductwork used to prevent the loss or gain of heat from or into the duct.

DUCTWORK:

A system used to move heated or cooled , filtered air through a building consisting of plenums, metal or flexible pipes. These are connected to such things as grilles, registers, boots and return drops. Plenums, trunks and drops may be constructed of sheet metal and or fiberglass duct board material.

EVAPORATOR COIL:

A series of aluminum or copper tubes usually covered with aluminum plates, used to remove heat and humidity as condensation in a cooling system. This part is usually mounted above or below the blower in a furnace or air handler and is an integral part of a package unit. There is a condensate drain attached to the coil and run to a floor drain, directly outdoors or to a condensate pump.

FAN CENTER:

An electrical control box consisting of a transformer and a relay used to be a connection point of the thermostat wires and to the furnace and condenser. It has the function of telling the various components within the system to open or close their operation. Primarily used on older furnaces as this function is now controlled from the CIRCUIT BOARD in newer furnaces.

FLUE:

A pipe or series of pipes used on a gas or oil furnace, fireplace or any other fossil fuel burning piece of heating equipment. This flue is connected to the heat exchanger and must be kept clean and in good condition.

GAS VALVE:

An electro/mechanical device used in a gas furnace or package heating unit. This device opens and closes on command of the building thermostat to inject gas into the heat exchanger through the burners.

IGNITION CONTROL:

The control in a gas or oil fired piece of equipment used to start the actual ignition within the gas furnace heat exchanger or oil furnace fire box.

INDOOR AIR BLOWER:

A motor driven wheel used to circulate or move air through a duct system.

INDUCER BLOWER:

A motor driven small wheel used to move air and gases through a heat exchanger.

HEAT EXCHANGER:

The metal enclosure in a gas furnace or oil furnace or package heating system where the gas or oil is burned. The air from the building is circulated around this enclosure and picks up heat to be sent to the occupied space through ductwork. In NO WAY can there be a connection between these gases that are burned and the air being delivered to the occupied space as carbon monoxide poisoning and death can be the result. A yearly check of your heating system should be done by a professional service technician. 

To see pictures of a  furnace heat exchanger being removed A Cracked Heat Exchanger.

HEATING:

To raise the temperature in a building by burning fossil fuels such as liquefied petroleum, natural gas, refrigeration, or with electricity using gas furnaces, boilers, heat pumps, and package air conditioning.

HEAT PUMP:

A heating and air conditioning piece of equipment used to both HEAT and COOL a building. This really is a "Reverse Acting Air Conditioner". It is capable of reversing the flow of refrigerant in a cooling system, therefore, extracting heat from outdoors which is then brought to the indoor coil in the AIR HANDLER and distributed to the building through ductwork. Additional ELECTRIC HEAT STRIPS are added to the AIR HANDLER to help heat the building if the outdoor temperature is extremely low.

HOT SURFACE IGNITOR:

This is a ceramic/carbon element which glows red and is used to ignite the gas and air mixture coming out of the burners in a gas furnace. This device replaces the old "PILOT" which had to continually be burning gas to operate. Much more efficient!

HOT WATER HEATING:

To raise the temperature of domestic hot water usually through the use of a gas water heater , an electric water heater or a boiler.

LIMIT SWITCH:

The safety control used in a gas or oil furnace or an air handler to limit the "HIGH" temperature.

LINE SET:

The copper tubing connecting the EVAPORATOR COIL to the CONDENSER. Also called the refrigerant lines.

PACKAGE HEAT:

A self contained piece of equipment used to heat a building usually mounted on a roof of a commercial building or at ground level to which ductwork is connected and run to various parts of the building for heating purposes.

PRESSURE SWITCH:

A switch usually used within a gas or oil furnace which "Senses" low combustion or improper drafting of the flue gases and will shut the furnace down on safety.

PILOT:

A part in a gas furnace which has a small orifice and burns a small amount of gas used to ignite the burners in a gas furnace on a call for heat.

PRINTED CIRCUIT BOARD:

An electronic control which sends signals to all operations of a furnace, air handler, oil burner or air conditioning condenser. To see a board click here See a Printed Circuit Board

SET BACK THERMOSTAT:

Also called an ELECTRONIC THERMOSTAT: A device used to monitor and adjust the building temperature and has set points which can be "PROGRAMMED" by the building owner to lower or raise the building temperature at given times. A great energy saver.

SWAMP COOLER:

Equipment which uses water sprayed over "pads" which then brings outside air into the building by means of ductwork or simply blown in through one central location. As the hot outside air passes over the wet pads the temperature of the air is reduced. No dehumidification takes place however.

THERMOCOUPLE:

A small tube filled with a material which generates a small amount of electricity and acts as a safety control within a gas furnace , gas water heater, gas boiler or a gas clothes dryer. This device is placed in the path of a burning pilot flame to sense that there is actually a pilot burning before the gas valve will allow gas to be sent to the burners.

THERMOSTAT:

An electric or electronic device used to regulate a control through the measurement of temperature.

We will be discussing a basic warm air heating and cooling SPLIT system here as would be found in an average home.

The FURNACE will be usually set in a crawl space under the house, in the attic, in a utility room or in a basement. There are also PACKAGE heating and cooling systems which incorporate the FURNACE, EVAPORATOR COIL and CONDENSING UNIT into one unit which sits outdoors. We will cover PACKAGE UNITS in another article. We will only discuss the FURNACE in this article.

Furnaces can be fired using natural gas, liquefied petroleum ( propane ), or oil. There are also HEAT PUMPS which use AIR HANDLERS in the place of a fuel fired FURNACE. ELECTRIC FURNACES are actually AIR HANDLERS and will be discussed in another article.

The furnace is equipped with a number of gas burners, a gas manifold, a gas valve, and an incoming gas line from the natural gas meter or propane tank outside the home. The burners are in a HEAT EXCHANGER which is where the gas is burned. Attached to the heat exchanger is a flue ( the pipe which exits the home usually through the roof ). This flue pipe carries the burned gases which has carbon monoxide in it as well as other harmful gases. On the newer furnaces there is also an inducer motor which aids in removing these gases and increases the efficiency of the furnace. It is extremely important that the HEAT EXCHANGER, FLUE, BURNERS and all related electrical valves, and safety controls be checked at least at the beginning of the heating season for safety as well as proper operation. A crack or rust hole in the HEAT EXCHANGER can prove deadly from carbon monoxide entering the living space. In the case of an OIL FURNACE the HEAT EXCHANGER is actually a FIRE BOX but serves the same purpose for this article. The burners are replaced with an oil pump and an oil GUN which sprays a mixture of oil and air into the fire box to be burned.

• A blower motor and blower wheel to distribute the heated or cooled air through an AIR FILTER and ductwork running to the different rooms in the building. Sometimes a belt connects the blower motor to the blower wheel.

• A high temperature limit control which will shut the furnace down should it overheat.

• A blower control which starts and stops the blower.

• A gas valve which works along with the thermostat mounted within the building.

• An inducer motor, pressure switch, flame roll out switch and other controls are used on the newer furnaces.

• Other parts are transformers, related wiring, regulators, gas shut offs, service disconnect switches and a host of others depending on the manufacturers design.

• OIL FURNACES also have different parts and controls, a few are: a much larger transformer, electrodes that fire the air/oil mixture, a flame eye, and an ignition control box, and a barometric draft regulator which is mounted in the flue pipe.

There are many different furnace efficiency ratings you can buy. The highest ratings are in the 90% and higher area.

We will discuss these efficiency ratings at length, in another article.

Some other aftermarket high efficiency air filters will go much longer between service, some have pleated paper elements which will need changing between 3 and 6 months. If you aren't sure of which kind you have, call your Heating and Air Conditioning Contractor, they are there to help you.