Facts

• Using electricity as its energy source, heat pumps are used for either the heating or cooling of your home by transferring heat between two reservoirs.
• In the warmer months, the heat pump acts like an air conditioner, removing heat from the air inside your home and transferring it outside.
• During colder months, heat from outdoor air is extracted and transferred to the interior of your home. Believe it or not, even a 32° Fahrenheit day produces enough heat to warm a home using a heat pump.

Benefits

• Year-round, energy-efficient indoor comfort for moderate climates –  A central heat pump helps maintain comfortable temperatures inside your home and reduces humidity levels year-round. Homes located in regions with severely cold temperatures may either require supplemental heating or be better served with an air conditioner/furnace combination.
• Cleaner air – As your heat pump system draws air out of various rooms in the house through return air ducts, the air is pulled through an air filter, which removes airborne particles such as dust and lint. Sophisticated filters may remove microscopic pollutants, as well. The filtered air is then routed to air supply duct-work that carries it back to rooms. Whenever the air conditioner is running, this cycle repeats continually, constantly filtering and cleaning the air in your home.
• Quieter operation – Because the compressor-bearing unit of the typical central heat pump system is located outside the home, the indoor noise level from its operation is much lower than that of a free-standing air conditioning unit.

How Central Air Conditioning Systems Work

Facts

• The typical central air conditioning system is a split system, with an outdoor air conditioning, or “compressor bearing unit” and an indoor coil, which is usually installed on top of the furnace in the home.
• Using electricity as its power source, the compressor pumps refrigerant through the system to gather heat and moisture from indoors and remove it from the home.
• Heat and moisture are removed from the home when warm air from inside the home is blown over the cooled indoor coil. The heat in the air transfers to the coil, thereby “cooling” the air.
• The heat that has transferred to the coil is then “pumped” to the exterior of the home, while the cooled air is pumped back inside, helping to maintain a comfortable indoor temperature.
• Central air conditioning can also be provided through a package unit or a heat pump.

Benefits

• Indoor comfort during warm weather – Central air conditioning helps keep your home cool and reduces humidity levels.
• Cleaner air – As your central air conditioning system draws air out of various rooms in the house through return air ducts, the air is pulled through an air filter, which removes airborne particles such as dust and lint. Sophisticated filters may remove microscopic pollutants, as well. The filtered air is then routed to air supply duct-work that carries it back to rooms.
• Quieter operation – Because the compressor bearing unit is located outside the home, the indoor noise level from its operation is much lower than that of a free-standing air conditioning unit.

How Central Heating Systems Work

Facts

• A furnace works to keep a home warm in the winter and plays a critical part in the operation of an air conditioning system.
• Furnaces produce heat through the combustion of natural gas in the furnace’s burner. The heat produced from this process then passes through a heat exchanger. Air from your home’s return air ducts is blown over the heat exchanger, thus warming the air.
• The furnace’s blower then blows the warmed air into the duct-work, which carries and disperses the warmed air throughout the home.
• During warmer months, the blower inside a furnace continues to circulate return air throughout the home–only this time, the return air has been cooled by being blown over the indoor coil portion of the home’s split-system air conditioning system. The condensing coil is typically installed on top of the furnace.

Benefits

• Indoor warmth any time it is required.
• Energy efficiency – The efficiency of a furnace can be determined by its AFUE – or Annual Fuel Utilization Efficiency. The minimum efficiency level for furnaces currently manufactured in the U.S. is 80% AFUE. A rating of “80% AFUE” means that for every dollar you spend heating your home; 80 cents are actually applied to the generation of warmth. Compared to many of the 60% AFUE furnaces in older homes, 80% AFUE furnaces are a significant improvement. However, for enhanced energy efficiency, you may wish to consider a 95+% AFUE furnace, such as a variable speed, 2 stage 96% AFUE Furnaces.
• Cleaner air – As your HVAC system draws air out of various rooms in the house through return air ducts, the air is pulled through an air filter, which removes airborne particles such as dust and lint. Sophisticated filters may remove microscopic pollutants, as well. The filtered air is then routed to air supply duct-work that carries it back to rooms. Whenever the HVAC system is running, this cycle repeats continually, constantly filtering and cleaning the air in your home.
• This cleaning process improves with the installation of a variable-speed furnace. Variable-speed furnaces use variable-speed blowers, which shift between several speeds. These furnaces will run longer at a low speed, which causes them to filter the indoor air more frequently.
• And remember – because the furnace plays an important role in the operation of the air conditioner, its variable-speed blower helps maintain both a consistent indoor temperature and improved air quality year-round.
• Possible Tax Credit – As part of the Energy Policy Act of 2005, the U.S. government has made a provision for tax credits of up to $200 for homeowners who install furnaces with an efficiency of 95% or greater until Dec. 31, 2011. Consumers should discuss these tax credits with a tax professional to see if they qualify.

AFUE:
Annual Fuel Utilization Efficiency. A measure of a furnace’s heating efficiency. The higher the AFUE%, the more efficient the product. The government’s established minimum AFUE rating for furnaces is 78%.

Air Handler:
In a cooling only or heat pump system, an air handler (also called a fan coil depending on installation application) takes the place of an evaporator coil and the variable speed fan from a gas powered furnace. Air handlers extract heat from the air with refrigerant supplied by the air conditioner (or heat pump) in the summer, and move heated air from the heat pump through the home’s ductwork during colder weather.

Balance Point:
An outdoor temperature, usually between 30° F and 45° F, at which a heat pump’s output exactly equals the heating needs of the home. Below the balance point, supplementary electric resistance heat is needed to maintain indoor comfort.

BTU:
British thermal unit. The amount of heat required to raise the temperature of one pound of water (about one pint) by one degree F.

Condensing Unit:
Normally referred to as an air conditioner or heat pump, a condensing unit functions as a heat transfer point. The heated refrigerant returned from the evaporator coil (or air handler/fan coil) located inside the home is sent outside to the air conditioner/heat pump where it is pressurized and sent through the condensing coil. Under high pressure the refrigerant gives up the heat which is dispelled into the outside air, thus cooling the refrigerant to then be sent back inside to the evaporator coil or air handler to repeat the process.

Evaporator Coil:
The portion of a central air conditioning system that is located in the home and connected to the furnace. It functions as the heat transfer point for cooling indoor air. An evaporator coil is comprised of a series of coils filled with refrigerant. As the warm/hot air from the home is returned to the HVAC system it blows through the evaporator coil where the refrigerant filled tubes extract both heat and extra moisture, thus cooling the air. When heating with a heat pump, this processed is reversed to provide heat.

Fan Coil:
(See Air Handler)

Heat Pump:
A heat pump is an all electric unit that cools like an air conditioner using refrigerant. The primary difference is that a heat pump can also provide heat by reversing the cooling process. Heat pumps extract heat from the air as even in cold weather, heat exists in the outside air. They then send the heated refrigerant inside to the coil to heat the indoor air. Heat pumps operate efficiently typically at temperatures of 40° F and above while a gas furnace is more efficient below 40° F.

Heat Source:
A body of air or liquid from which heat is collected. With heat pumps, the air outside the home is used as the heat source during the heating cycle. For geothermal heat pumps (also referred to as ground or water source) heat is removed from the earth or body of water.

HSPF:
Heating Seasonal Performance Factor. A measure of a heat pump’s heating efficiency. The higher the HSPF, the more efficient the product. There is no government established minimum HSPF rating for heat pumps.

MERV:
The Minimum Efficiency Reporting Value is the standard comparison of the efficiency of an air filter/air cleaner. The MERV scale ranges from 1 (least efficient) to 16 (most efficient), and measures a filter’s ability remove particles from 3 to 10 microns in size.

Packaged System:
A year-round heating and air conditioning system that has all of the components of a normal split system completely encased in one unit. These are located outside the home either on the roof or concrete slab in the yard. Packaged systems can come as cooling only, cooling and gas furnace, heat pump (all electric) or hybrid (electric cooling with dual fuel source heating).

Refrigerant:
A chemical that produces a refrigerating effect while expanding and vaporizing. Most residential air conditioning systems contain R-410A or R22 refrigerant. R-410A is the new government mandate for air conditioners and heat pumps since R-22 has been proven to be dangerous to the environment.

SEER:
Seasonal Energy Efficiency Ratio. A measure of the amount of energy an air conditioner or heat pump requires to cool a certain space. The higher the SEER, the more efficient the product. The government’s established minimum SEER rating for air conditioners manufactured after January 2006 is 13.

Split System:
An air conditioning and heating system with components located both inside and outside the home. This is the most common design for home use.

Supplementary Heat:
The auxiliary or emergency heat, usually electrical resistance heat, provided at temperatures below a heat pump’s balance point.

Ventilator (Air Exchanger):
Part of a complete indoor air quality solution, a ventilator exchanges stale indoor air with fresh air from outside with minimal energy loss regardless of the temperature/humidity level outside.

UV Lamp (UVC):
Part of a complete indoor air quality solution, UV lamps are often mounted in the evaporator coil to kill mold for the purpose of purifying the air and maintaining efficient operation of the coils.

Zoning:
A method of dividing a home into different comfort zones, so each zone can be independently controlled, depending on use and need.

Next, the system should be run through a full heating cycle to ensure that it has plenty of combustion air and chimney draft. Finally, cleaning the burner and heat exchanger to remove soot and other gunk will prevent such buildup from impeding smooth operation. For the burner, efficiency hinges on adjusting the flame to the right size and color, adjusting the flow of gas or changing the fuel filter in an oil-fired system. A check of the heat pump should include an inspection of the compressor, fan, indoor and outdoor coils and refrigerant lines. Indoor and outdoor coils should be cleaned, and the refrigerant pressure should be checked.

Blower
Tuning up the distribution side of a forced-air system starts with the blower. The axle should be lubricated, blades cleaned and blower motor checked to insure the unit isn’t being overloaded. The fan belt should be adjusted so it deflects no more than an inch when pressed. Every accessible joint in the ductwork should be sealed with mastic or UL-approved duct tapes. Any ducts that run outside the heated space should be insulated. On a hot-water system, the expansion tank should be drained, the circulating pump cleaned and lubricated and air bled out of the radiators.

Thermostat
While thermostats rarely fail outright, they can degrade over time as mechanical parts stick or lose their calibration. Older units will send faulty signals if they’ve been knocked out of level or have dirty switches. To recalibrate an older unit, use a wrench to adjust the nut on the back of the mercury switch until it turns the system on and, using a room thermometer, set it to the correct temperature. Modern electronic thermostats, sealed at the factory to keep out dust and grime, rarely need adjusting. However, whether your thermostat is old or young, the hole where the thermostat wire comes through the wall needs to be caulked, or a draft could trick it into thinking the room is warmer or colder than it really is.

Humidifier
A neglected in-duct humidifier can breed mildew and bacteria, not to mention add too much moisture to a house. A common mistake with humidifiers is leaving them on after the heating season ends. Change the water pad every year. Clean the drain out and test operation.

Filters
Most houses with forced-air furnaces have a standard furnace filter made from loosely woven spun-glass fibers designed to keep it and its ductwork clean. Unfortunately, they don’t improve indoor air quality. That takes a media filter, which sits in between the main return duct and the blower cabinet. Made of a deeply pleated, paper-like material, media filters are at least seven times better than a standard filter at removing dust and other particles. An upgrade to a pleated media filter will cleanse the air of everything from insecticide dust to flu viruses. Compressed, media filters are usually no wider than six inches, but the pleated material can cover up to 75 square feet when stretched out. This increased area of filtration accounts for the filter’s long life, which can exceed two years. The only drawback to a media filter is its tight weave, which can restrict a furnace’s ability to blow air through the house. To insure a steady, strong airflow through the house, choose a filter that matches your blower’s capacity.

Duct Cleaning
A maze of heating and air conditioning ducts runs inside the walls and floors of 80 percent of American homes. As the supply ducts blow air into the rooms, return ducts inhale airborne dust and suck it back into the blower. Add moisture to this mixture and you’ve got a breeding ground for allergy-inducing molds, mites and bacteria. Many filters commonly used today can’t keep dust and debris from streaming into the air and over time sizable accumulations can form — think dust bunnies, but bigger.

To find out if your ducts need cleaning, pull off some supply and return registers and take a look. If a new furnace is being installed, you should probably invest in a duct cleaning at the same time, because chances are the new blower will be more powerful than the old one and will stir up a lot of dust.

Professional duct cleaners tout such benefits as cleaner indoor air, longer equipment life and lower energy costs. Clean HVAC systems can also perform more efficiently, which may decrease energy costs, and last longer, reducing the need for costly replacement or repairs. Cleaning has little effect on air quality, primarily because most indoor dust drifts in from the outdoors. But it does get rid of the stuff that mold and bacteria grow on, and that means less of it gets airborne, a boon to allergy sufferers.