AFUE
Annual Fuel Utilization Efficiency. Refers to the ratio of annual output of
useful energy to the annual energy input to the furnace. The higher the AFUE,
the more efficient the furnace.
Balancing
The process of adjusting the flow of air in duct systems, or water flow in hot-water
heating systems. Proper balancing is performed using accurate instrumentation
to deliver the right amount of heating or cooling to each area or room of the
home.
BTU
British Thermal Unit. The quantity of heat required to raise the temperature
of 1 lb. of water 1° F.
Central Forced-Air Heating System
A piece of equipment that produces heat in a centralized area, then distributes
it throughout the home through a duct system.
Configuration
The orientation of the furnace and the direction of airflow through it. A furnace
may have an upflow, downflow or crossflow (horizontal) configuration.
Damper
A device that is located in ductwork to adjust air flow. There are basically
two types of dampers: manual and motorized. A manual damper generally consists
of a sheet metal (or similar material) flap, shaped to fit the inside of a round
or rectangular duct. By rotating a handle located outside of the duct, a technician
can adjust air flow to match the needs of a particular area or room (see Balancing).
A motorized damper is generally used in a zoned system to automatically deliver
conditioned air to specific rooms or zones (see Zone Control).
DSM
Demand-side Management (DSM) encourages customers to control their electricity usage. It includes opportunities
for conservation, energy efficiency, load shifting and peak-shaving activities.
Ductwork
The delivery system through which conditioned air is sent throughout the home
and returned to the heating and cooling system. Ductwork is made of sheet metal,
fiberglass, or flexible plastic, and can be round or rectangular in shape.
Efficiency
The rate at which a furnace maximizes fuel use. This rate is numerically described
as a ratio called AFUE (see AFUE). As of January, 1992, no furnaces can be manufactured
with efficiencies lower than 78 percent AFUE. High-efficiency furnaces will
be rated 88 to 97 percent AFUE. See also SEER and HSPF for efficiency ratings
for heat pump systems.
Electronic Ignition
A device that eliminates the need for a continuously burning pilot. These and
many other features let the mid-efficiency furnace satisfy your heating needs
with less energy than your existing furnace.
Forced Air
A type of heating system that uses a blower motor to move air through the furnace,
into the ductwork, and into the living area.
Heat Exchanger
Enables furnaces to safely transfer heat from combustion into breathable air.
The primary heat exchanger transfers heat from combustion gases to the air blowing
through the ductwork, never allowing combustion gas into the air stream. The
primary heat exchanger handles the hottest gases. In high-efficiency furnaces,
secondary heat exchangers recover heat that used to be vented up the chimney
with the exhaust gases. By recovering this heat, the furnace becomes more efficient.
HSPF (Heating Seasonal Performance Factor) HSPF is one of two energy efficiency ratings for heat pump systems (SEER
is the other). The HSPF rating measures operating efficiency during the heating
season. The higher the HSPF rating, the more efficiently the system will perform.
Hydronic Heating
System that delivers heat from water heated by a boiler to baseboard fintube
or to another style of water-to-air heat exchanger.
R-Value R-value is a measure of how well insulation will resist the flow of heat.
Higher R-values mean greater insulating ability, which means greater household
energy savings and greater cost savings.
SEER (Seasonal Energy Efficiency Rating) SEER is the other energy efficiency rating for heat pump systems (HSPF
is the other). The SEER rating measures operating efficiency during the cooling
season. The higher the SEER rating, the more efficiently the system will perform.
SEER is also used to rate central air-conditioning systems.
Sizing
The procedure a heating contractor uses to determine the proper system size
needed to heat and/or cool a home efficiently. For instance, a system that is
sized too small won't deliver enough heat, while a system sized too large increases
energy costs and can have an adverse effect on comfort. Sizing depends on the
square-footage of the home, the amount of ceiling and wall insulation, the window
area, use of storm doors, storm windows, and more.
Therm
Another measurement of heat. One therm equals 100,000 BTUs.
TOU
The Time-of-Use rate (TOU) is designed to reward customers who are willing
to reduce their energy consumption during on-peak hours. TOU complements Demand-side
Management (DSM).
Zone Control
A system in which living areas are divided into separate spaces and the 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 (see Damper).
