Air Conditioner:
Device used to control temperature, humidity, cleanliness and movement of air
in a confined space.
Air Conditioning:
Control of the temperature, humidity, air movement and cleaning of air in a
confined space.
BTU (British Thermal Unit):
The amount of heat that will raise or lower one pound of water 1
degree F. at 39.2 degrees F. One BTU is the equivalent of the heat given off by a single wooden
kitchen match. The British Thermal Unit is a standard of measure for cooling and heating
capacities. This is how the capacity of air conditioning is measured. A standard measure of heat
energy in the U.S., commonly used to measure the energy content of various fuels and steam. It
takes one Btu to raise the temperature of one pound of water by one degree Fahrenheit at sea
level. For example, it takes about 2,000 Btus to make a pot of coffee. One Btu is equivalent to 252
calories, 778 foot-pounds, 1055 joules, and 0.293 watt-hours. Note: In the abbreviation, only the
B is capitalized. For your home, it represents the measure of heat givens off when fuel is burned
for heating or the measure of heat extracted from your home for cooling.
Chiller:
A device that produces chilled water to provide air conditioning for large buildings or
cooling for process applications. A device that cools water, usually to between 40 and 50 degrees
Fahrenheit for eventual use in cooling air
Compressor:
The heart of an air conditioning or heat pump system. The large (usually black) part
in the condenser (outdoor unit) that pumps refrigerant. The pump of a refrigerating mechanism
which draws a low pressure on cooling side of refrigerant cycle and squeezes or compresses the
gas into the high pressure or condensing side of the cycle. The compressor maintains adequate
pressure to cause refrigerant to flow in sufficient quantities to meet the cooling requirements of
the system.
Condenser:
This is the unit that will sit outside and is part of a split system, it contains the
compressor which is the heart of your air conditioner or Heat Pump, it pumps the refrigerant
through your system. Some people call the condenser the compressor, but the compressor is a
component of the condenser along with the fan motor and condenser coil. Coil or outdoor coil
dissipates heat from the refrigerant, changing the refrigerant from vapor to liquid.
ACH:
Air Changes Per Hour. The number of times that air in a house is completely replaced with
outdoor air in one hour.
Actuator:
That portion of a regulating valve which converts mechanical fluid, thermal energy or
electrical energy into mechanical motion to open or close the valve seats
AHU (Air Handler Unit):
The inside part of the A/C system that contains the blower, cooling
(evaporator) coil, and heater. The part of an HVAC system responsible for moving air, which may
also clean, heat, or cool the air. This refers to equipment used to provide conditioned air to a
space. The air handler unit generally includes a blower or fan, heating and/or cooling coils, and
related equipment such as controls, condensate drain pans, and air filters. Does not include
ductwork, registers or grilles, or boilers and chillers.
Air Change:
The amount of air required to completely replace the air in a room or building; not to
be confused with recirculated air.
Air Diffuser:
An air distribution outlet or grille designed to direct airflow into desired patterns.
Supply air terminal device, designed to direct airflow into desired patterns, usually placed in the
ceiling, generally of circular, square or rectangular shape, and composed of divergent deflecting
members.
Air Handler:
an-blower, filter and housing parts of a system. Fan-blower, filter, heat transfer coil,
and housing parts of a system. Also known as the blower section and part of the split system, this
unit is commonly in your home or attic and blows the air through your house. This has to be
matched with the condenser properly to assure maximum efficiency. This will contain your heating
and evaporator coil.
Air Infiltration:
Leakage of air into rooms through cracks, windows doors and other openings.
Dampers:
Controls that vary airflow through an air outlet, inlet, or duct. A damper position may
be immovable, manually adjustable or part of an automated control system.
Dehumidification:
The reduction of water vapor in air by cooling the air below the dew point;
removal of water vapor from air by chemical means, refrigeration, etc.
Dewpoint:
Is the temperature at which air becomes saturated with water and begins to condense
- forming a dew. Therefore at 100 % RH the ambient or process temperature equals the dewpoint
temperature. The more negative the dewpoint temperature is from the ambient temperature the
less the risk of condensation and the drier the gas or air stream.
Direct Expansion:
(Refrigeration) Any system that, in operation between an environment where
heat is absorbed (heat source), and an environment into which unwanted heat is directed (heat
sink) at two different temperatures, is able to absorb heat from the heat source at the lower
temperature and reject heat to the heat sink at the higher temperature. The cooling effect is
obtained directly from a fluid called a refrigerant that absorbs heat at a low temperature and
pressure, and transfers heat at a higher temperature and higher pressure.
Dry Bulb Temperature:
(DB) The temperature measured by a standard thermometer. A measure
of the sensible temperature of air.
Economizer, Air:
A ducting arrangement and automatic control system that allows a heating,
ventilation and air conditioning (HVAC) system to supply up to 100 percent outside air to satisfy
cooling demands, even if additional mechanical cooling is required.
Economizer,
Water: A system which uses either direct evaporative cooling, or a secondary
evaporatively cooled water loop and cooling coil to satisfy cooling loads, even if additional
mechanical cooling is required.
EER: -
(Energy Efficiency Ratio) A ratio calculated by dividing the cooling capacity in Btu's per
hour (Btuh) by the power input in watts at any given set of rating conditions, expressed in Btuh
per watt (Btuh/watt). EER & SEER can not be compared equally. Air source equipment is rated by
SEER and geothermal equipment is rated by EER. EER changes with the inside and outside
conditions, falling as the temperature difference between inside and outside gets larger.
Electrostatic air cleaner:
A device that uses an electrical charge to trap particles traveling in the
air stream.
ERV:
(Energy Recovery Ventilator) This device preheats incoming outside air during the winter
and pre-cools incoming air during the summer to reduce the impact of heating and or cooling the
indoor air. This means that smaller capacity heating and cooling systems can be used in homes,
which results in lower installation costs, lower peak demand for energy, and lower operating costs.
Exhaust:
Air removed deliberately from a space, by a fan or other means, usually to remove
contaminants from a location near their source. The air flow leaving the treated space. Exhaust
may be accomplished by one or more of the following methods:
Package Unit or Package System:
A self-contained unit or system that has the Air Handler &
Condenser in same unit. Normally placed outside the home and connected to a duct system by a
penetration through the homes foundation. Except for geothermal which is a self-contained indoor
unit that is place in a closet, attached garage, basement, or mechanical room.
Positive Pressure:
Condition that exists when more air is supplied to a space than is exhausted,
so the air pressure within that space is greater than that in surrounding areas. Under this
condition, if an opening exists, air will flow from the positively pressurized space, outward to
surrounding areas.
VFD:
(Variable Frequency Drive) Electronic speed control for motors.
Wet-bulb Temperature:
When a wet wick is placed over a standard thermometer and air is
blown across the surface, the water evaporates and cools the thermometer below the dry-bulb
temperature. This cooler temperature (called the wet-bulb temperature) depends on how much
moisture is in the air.
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