Though your definitions of “comfort”
may be different than your neighbor’s, knowing
these terms can help make your search for improved
comfort and efficiency much less confusing and much
more effective.
A-coil:
a heat exchanger consisting of two diagonal coils
that are joined together in the shape of
the letter A.
Access fitting: a valve that provides
a port or creates an opening to a sealed system.
Acid condition: the presence of
corrosive substances in a sealed refrigeration system.
ACR tubing: copper tubing that
is specially sized and sealed for use in air conditioning
and
refrigeration systems.
AFUE: Annual Fuel Utilization
Efficiency. 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 percent
of the fuel is used to provide
warmth to your home, while the remaining 10 percent
escapes as exhaust.
Air conditioner: a device that
modifies the temperature, humidity, cleanliness,
or general quality
of air.
Air conditioning: the science of
controlling the temperature, humidity, cleanliness
or general quality
of air. Abbreviated: ac.
Air diffuser: an air supply outlet
that delivers air in a specific pattern.
Air handler: air moving and/or
mixing unit; may include blower, filters, dampers,
etc.
Ambient temperature: the temperature
of the immediately surrounding air or area.
Amperage: the rate of electrical
current flow in a circuit.
Anticipator: a thermostat component
that compensates for the control's thermal lag.
Bearing:
a surface or roller designed to minimize friction
between moving parts.
Belt drive: a means of transferring
rotating force from a prime mover (such as a motor)
to a pump
or compressor.
Blower: an air-moving device; a
fan.
Boiler: a sealed chamber in which
water is converted to steam or is heated for circulation
in a
hydronic heating system.
Boot: a fitting that connects round
to rectangular sheet metal ducts.
BTU: British thermal unit.
the amount of heat that will raise or lower the
temperature of one pound
of water one degree Fahrenheit.
Bulb sensing: a fluid-filled bulb
that responds to a temperature remote from its control.
Burner: a device that utilizes
fuel to support combustion.
BUTH: BTU per hour. A measurement
used to size HVACR equipment.
Bypass: a piping detour around
a component; to circumvent any part of a circuit.
Calibrate:
to adjust a control or device in order to maintain
its accuracy.
Cap: a fitting that seals off the
end of a tube or pipe.
Capacity: The output or producing
ability of a piece of cooling or heating equipment.
Cooling and
heating capacities are referred to on BTUs.
Capillary tube: a small diameter
tubing used in pressure sensing devices or as a
metering device
in refrigeration systems. Also called a cap tube.
Carbon monoxide: CO; a poisonous
gas produced by incomplete combustion.
Celsius (centigrade): the metric
temperature scale in which water freezes at 0 deg.
And boils at
100 degrees.
Central system: an air conditioning
system controlled from or having all its main components
located
at a single point.
CFC chlorofluorocarbon: An ozone-depleting
refrigerant that is being phased out.
CFM: Cubic Feet Per Minute.
A standard measurement of airflow. A typical system
requires 400
CFM per ton of air conditioning.
Check valve: a control fitting
that permits the flow of fluid in one direction
only.
Chiller: 1. a cooler that refrigerates
a secondary refrigerant, such as water or brine,
for circulation
elsewhere. 2. Any machine that lowers the temperature
of a fluid.
Chimney or flue: a vent for the
products of combustion.
Circuit: 1. a path for electrical
flow. 2. A complete, closed loop for fluid circulation.
Circuit
breaker: a resettable switch that opens an electrical
circuit in case of an excessive
current flow.
Circulator: a pump used to push
water through a hydronic system.
Coil: 1. a section of more than
one length of pipe or tubing used to transfer heat.
2. a
wire winding or loop.
Combustion: burning; the rapid
oxidation that results from combining fuel, heat,
and air.
Compressor: The heart of an air
conditioning or heat pump system. It is part of
the outdoor unit
and pumps refrigerant in order to meet the cooling
requirements of the system.
Condensate/condensation: water
vapor that liquefies due to the lowering of its
temperature to
the saturation point.
Condensate pump: a water pump that
disposes of or recirculates collected condensate.
Condenser: a heat exchanger in
which compressed refrigerant vapor is cooled until
it becomes
a liquid.
Condenser fan: the fan that circulates
air over and air cooled condenser. (usually located
outside)
Condensing unit: the components
that intake low-temperature/pressure refrigerant
and convert
it to a liquid suitable for the absorption of more
heat; the compressor,
condenser, receiver and their controls.
Contactor: a switch that can repeatedly
cycle, making and breaking an electrical circuit.
When
sufficient current flows through a coil built into
the contactor, the resulting magnetic
field causes the contacts to be pulled in.
Coupling: a straight fitting for
two lengths of pipe or tubing.
Damper:
Found in ductwork, this movable plate opens and
closes to control airflow. Dampers can
be used to balance airflow in a duct system. They
are also used in zoning to regulate
airflow to certain rooms.
Damper motor: a motor which, through
mechanical linkage, opens or closes a damper automatically.
Data plate: an equipment identification
label; usually lists model and serial numbers and
various
unit ratings.
Degree day: the difference between
indoor design temperature and each day's average
outdoor
temperature. Abbreviated: DD.
Dehumidifier: an air conditioner
that removes moisture from air by cooling it.
Demand meter: an instrument that
measures electrical power consumption, usually in
kilowatt-hours.
Dew point: the temperature at which
water vapor begins to condense out of humid air.
Diffuser: a grille over an air
supply duct with vanes to distribute the discharging
air in a specific
pattern or direction.
Disconnect: a switch box that cuts
off electrical power to a machine being serviced.
Door switch: a circuit control
that is made and broken by the opening and closing
of the equipment's
door or lid.
Downflow furnace: a furnace that
intakes air at its top and discharges it near its
bottom.
Draft diverter: a fitting on the
furnace flue that draws in room air to dilute the
exhaust gases. It
also minimizes the effect of downdrafts and extreme
updrafts in the flue.
Drier: an accessory that removes
moisture from a refrigeration system.
Drip pan: a pan used to collect
evaporator condensate.
Duct: a pipe or conduit through
which air is delivered.
Duct heater: an electric-resistance
or hot water heater mounted inside an air-delivery
duct to provide
supplementary heat to the delivered air.
Ductwork: pipes or channels that
carry air throughout your home. In a home comfort
system, ductwork
is critical to performance, in fact, it's as critical
as the equipment.
Economizer:
a system of controls and dampers on an air conditioning
system that mixes varying
volumes of outdoor air with air in the conditioned
space. This saves money
by using outdoor air for cooling whenever it is
cold enough.
EER - energy efficiency ratio:
the number of BTU produced per watt of electrical
power consumed
by an air conditioner.
Efficiency: the amount of usable
energy produced by a machine, divided by the amount
of energy
supplied to it.
Elbow: any fitting that produces
a bend in the duct or piping run it connects.
Electric heat: a heating system
in which the energy source is electricity and the
heat is produced
by resistance elements.
Electronic leak detector: a test
instrument that detects the presence of halide refrigerants
in
small air samples.
Electrostatic filter or precipitator:
an air cleaning device that electrically charges
foreign particles
in the air and then collects them on positively
charges
plates.
Evacuate: to remove, through the
use of a vacuum pump, all moisture and noncondensables
from
a system.
Evaporator coil or Indoor coil:
The other half of your air conditioning system located
inside your
home in the indoor unit. This is where the refrigerant
evaporates
as it absorbs heat from the air that passes over
the
coil.
Fahrenheit:
the temperature scale on which water freezes at
32 deg. And boils at 212 deg.
Fan coil: a heating and/or cooling
unit consisting of a finned-tube coil and fan in
a package.
Filter: a device that removes impurities
from a fluid through a mechanical straining process.
FLA - full load amperage:
the current draw of a motor under full load, the
current flow in a circuit
when the load is at its rated peak.
Flexible duct: a duct that can
be gradually bent to go around obstacles.
Flue: a vent that carries the products
of combustion from a boiler or furnace.
Furnace: that part of the heating
system in which combustion and heat transfer occur.
Fuse: a metal strip in an electrical
circuit that melts and breaks the circuit when excessive
current flows through it.
Gas
Furnace Heat Exchanger: Located in the
furnace, the heat exchanger transfers heat to the
surrounding air, which is then pumped throughout
your home.
Gas valve: a valve that controls
fuel flow to the burner in a gas-fired furnace or
heater.
Grille: a cage-like panel that
covers the end of a duct, permitting the passage
of air but not foreign
objects.
HCFC:
hydrochlorofluorocarbon, a refrigerant. Sometimes
abbreviated to HFC.
Head pressure: high-side pressure
in a refrigeration system; pressure from the compressor
discharge
to the metering device.
Heat exchanger: any device that
transfers heat from one substance to another substance.
Heat pump: a mechanical-compression
cycle refrigeration system that can be reversed
to either
heat or cool a conditioned space.
High-efficiency gas furnace: a
furnace that recycles combustion gases to obtain
efficiencies
of 85% to 95%.
Horizontal furnace: a short furnace
with intake at one end and discharge out the other.
HSPF - Heating Seasonal Performance
Factor: ratio of the total seasonal heating
requirements
(BTU), including supplemental electric heat, during
annual usage period for
heating, divided by the total electric power consumption
in watts during the same period.
(measurement for rating heat pump efficiency)
Humidifier: a machine that adds
water vapor to air to increase its relative humidity.
Humidistat: a humidity-sensing
control that cycles the humidifier on and off.
IAQ:
indoor air quality; an HVACR field that deals with
developing and maintaining a building's
indoor air system so that it is clean, healthful
and comfortable for the occupants of the building.
Intelligent building: a structure
in which all aspects of air quality and operation
are monitored
and controlled by digital computers.
Liquid
line: the refrigerant tubing extending
from the condenser outlet to the metering device.
Usually
the small warm line.
Locked rotor amperage (LRA): the
current drawn by a motor at start-up, before the
rotor starts
turning.
Low ambient control: a device for
maintaining high-side pressure when the temperatures
around an air-cooled condenser are abnormally low.
OEM:
original equipment manufacturer.
Overcharge: to fill a system with
refrigerant beyond its design capacity.
Package
unit: a system with all the major components
contained in a single cabinet or installed
in a single location, as opposed to a split system
with remote components.
Preventative maintenance: the scheduled
inspection and replacement of short-lived components
in order to avoid untimely and expensive emergency
repairs.
Pump down: to use the compressor
to pump all of the system's refrigerant into the
receiver and/or
condenser prior to opening the system for service.
This is also used in commercial
systems to prevent refrigerant migration in the
off cycle.
Refrigerant:
A chemical that produces a refrigerating effect
while expanding and vaporizing. Most
residential air conditioning systems contain R-22
refrigerant. R-22 is regulated
by international controls under the Montreal Protocol
and in the United States
by the Environmental Protection Agency. It is scheduled
to be in production
until the year 2020. It's used in approximately
95 percent of air conditioning
equipment manufactured in the U.S. today.
Refrigerant reclaim: the process
of returning recovered refrigerant to new product
specifications.
This is usually performed at a reprocessing facility.
Refrigerant recovery: the process
of removing refrigerant from a system and placing
it in a container.
Refrigerant recycling: the process
of cleaning recovered refrigerant by reducing contaminant
levels with filters, on site.
Register: a grille with adjustable
louvers or dampers for controlling the direction
of discharge air.
Relay: an electrical switch controlled
by the flow of current in a separate or parallel
circuit.
Retrofit: the process of changing
the design or equipment to incorporate modern features
or later
improvements.
Return intake: an opening through
which air is exhausted from a conditioned space.
Reversing valve: an electrical,
four-way valve in a heat pump that diverts refrigerant
flow according
to whether cooling or heating is needed; also called
a four-way valve.
SEER
- Seasonal Energy Efficiency Ratio: A measure
of cooling efficiency for air conditioners and
heat pumps. The higher the seer, the more energy
efficient the unit. The government's
minimum SEER rating is 10. (It's similar to comparing
miles per gallon in
automobiles.)
Short cycling: continual starting
and stopping of a system over a shorter-than-normal
time period,
due to a malfunction.
Single-phasing: the dropping out
of a leg in a three-phase circuit. The motor continues
to run
as a single-phase motor, causing the motor to overheat
and burn out.
Split system: The combination of
an outdoor unit (air conditioner or heat pump) with
an indoor unit
(furnace or air handler). Split systems must be
matched for optimum efficiency.
Squirrel cage: the wheel of a centrifugal
fan, so called due to its resemblance to rotary
exercise
wheels.
Subbase: a thermostat mounting
plate that incorporates operating circuitry into
its construction.
Suction line: the refrigerant piping
from the evaporator outlet to the compressor inlet.
(It is the
larger, cold insulated refrigerant line.)
Thermocouple:
two dissimilar metal conductors welded together.
When their junction is
heated, a voltage is produced. It is used as a safety
device in a gas burner
system.
Thermostat: A thermostat consists
of a series of sensors and relays that monitor and
control the
functions of a heating and cooling system.
Ton: A unit of measurement used
for determining cooling capacity. One ton is the
equivalent of
12,000 BTUs per hour.
Transformer: a set of coils that
increases or decreases voltage by induction.
TXV - thermostatic expansion
valve: a valve that controls the flow of refrigerant.
It is operated by
evaporator temperature and pressure.
Undercharged:
a refrigeration system that is short of refrigerant.
Universal replacement part: a part
that can be used as a replacement part for many
different
models, including equipment of different manufacturers.
Upflow furnace: a heater in which
air is drawn in through the sides or bottom and
discharged
out the top.
Vacuum:
any pressure below atmospheric pressure.
Vacuum pump: a vapor pump capable
of creating the degree of vacuum necessary to evaporate
moisture near room temperature.
Zoning:
A method of dividing a home into different comfort
zones so each zone can be independently
controlled depending on use and need.
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