HVAC Systems Vocabulary

Vocabulary flashcards related to Heating, Ventilation, and Air Conditioning (HVAC) Systems.

Air Conditioning

The simultaneous control of air temperature, humidity, motion, and air purity in a confined space.

Air Conditioner

A device which provides air-conditioning.

Heat

A form of energy that is transformed by temperature difference.

Enthalpy

Quantity of heat BTU/min., whether in fluid or gas.

Condenser

A heat-exchange device in a refrigeration system in which refrigerant vapor is liquefied by the removal of heat.

Compressor

A machine for drawing refrigerant from the evaporator at a relatively low pressure, compressing it before discharging it into the condenser.

Evaporator

The part of a refrigeration system in which refrigerant is vaporized, thereby taking up external heat and producing cooling.

Convection

Heat transmission, either natural or forced, by currents resulting from differences in density due to temperature difference in the heated space.

Humidity

Water vapor within a confined space or environment.

Relative Humidity

Ratio of weight of water vapor actually found in humid air to the maximum possible weight of water vapor that air could contain at the same temperature.

Humidity Ratio

Weight of water vapor in a mixture per pound of dry air.

Humidistat/Hygrostat

A regulatory device actuated by changes in humidity.

Thermostat

A device that responds to changes in temperature, directly or indirectly.

Adiabatic Saturation

The introduction of water into unsaturated air to increase humidity ratio but without transfer of heat to or from an outside source.

Dew Point

Temperature at which air-water vapor mixture will become saturated and begin to yield drops of condensed water.

Latent Heat

The amount of heat which is absorbed or evolved in changing the state of the substance without changing its temperature.

Latent Heat of Fusion

One where the change is from a liquid to a solid state.

Latent Heat of Vaporization

One where the change is from a liquid to a gaseous state.

Sensible Heat

Heat in BTU absorbed by a substance in changing its temperature without changing its state.

Wet Bulb Temperature

Temperature shown by a thermometer with a wetted bulb rotated rapidly in the air to cause evaporation of its moisture.

Dry Bulb Temperature

Temperature of air-water vapor mixture as measured in the normal way with a °F thermometer.

Desiccant

An absorber which could be liquid or solid that can remove water vapor from a material.

Damper

A device used to vary the volume of air passing through an air outlet, inlet, or duct.

Duct/Air-Conditioning Duct/Air Duct

A passageway usually fabricated of metal, fiberglass, concrete, or cement and asbestos fibers; used to transfer air from one location to another.

Filter

A device used to separate solids such as dirt, dust, and other particles from air.

Refrigerant

A substance which produces the refrigerating effect by absorbing heat while expanding or evaporating.

Freon

A synthetic chemical refrigerant.

Ventilation

Process of supplying or removing air by natural methods or mechanical means to or from any space.

Ton of Refrigeration

The useful refrigerating effect equal to 211 KJ/min or 288,000 BTU/24hrs, or 12,000 BTU/hr.

Condensing Unit

A specific refrigerating machine combination for a given refrigerant.

Expansion Coil

An evaporator constructed with a pipe or tubing.

Generator

Any device equipped with a heating element used in the refrigerating system to increase the pressure of the refrigerant.

Air Conditioning Machinery

Equipment including any or all of the following: compressor, condenser, generator, evaporator, absorber, receiver, connecting pipe, air handling units, dehumidifier, heat exchanger.

Unit Air Conditioner

A type of system used for small installations such as residences and small offices.

Split-type Air Conditioner

A unit comprised of two separate sections, one installed inside the room with another installed outside the building.

Centralized Air Conditioner

A type of air-conditioning system used for large installations with the use of ducts.

Cooling Tower

A structure usually located on the roof of a building over which water is circulated so as to cool it evaporatively in contact with air.

AFUE (Annual Fuel Utilization Efficiency)

The ratio of annual fuel output energy to annual input energy.

COP (Coefficient of Performance)

For Cooling – the ratio of the heat removal to the rate of energy input, for Heating – the ratio of the heat delivered to the rate of energy input.

EER (Energy Efficiency Ratio)

Ratio of net equipment cooling capacity in BTU/hr to the total rate of electric input in watts.

IPLV (Integrated Part Load Value)

A single-number figure of merit based on part-load EER or COP.

SEER (Seasonal Energy Efficiency Ratio)

The total cooling output of an air-conditioner during its normal annual usage, in BTU/hr, divided by the total energy input during the same period in watt-hours.

Conduction

Transfer of heat from one place of higher temperature to a place of lower temperature of the same body to another which it is in contact with.

Convection

The transfer of hear by motion of the particles of the heated substance.

Radiation

The process of transmitting rays of heat through the air.

Cooling and dehumidifying

A system involved in air conditioning, removes moisture from the air and lowers its temperature

Heating and humidifying of air

A system involved in air conditioning, adds heat and moisture to the air.

Cleaning of air (filtration)

A system involved in air conditioning, removes dust, pollen, and other particles from the air.

Circulation of air

A system involved in air conditioning, distributes air throughout the space.

Air-conditioning Standards

Standards that must be taken into account in providing satisfactory conditions for spaces intended for human usage and occupancy, including heating and dehumidifying, cooling and dehumidifying, air flow and air supply.

Refrigeration and Air-Conditioning Standards

According to mechanical regulations – NBC, the temperature and humidity of air to be used for comfortable cooling shall be maintained at 68 – 74°F effective temperature at an air movement or 4.57 – 7.60 mpm within the living zone.

Summer Air Conditioning

Consists of cooling and dehumidifying by passing air through sprays of cold water, passing air through a combination of cold water sprays and cooling coils, or passing air through refrigeration coils.

Mechanical Refrigeration

Based upon the alternate liquefying and evaporating of a volatile liquid refrigerant with a low boiling point.

Cooling by Absorption

Heat absorption is one form of cooling that uses evaporation and absorption to cool an area by dissolving up a coolant such that it turns into vapor, before mixing it into a solution with another coolant and then heating the result to restore the first coolant to its original state.

Thermoelectric Cooling

A direct current passes through the circuit of a thermocouple, then heat is given off at one junction and absorbed at the other.

Design Considerations for Air Conditioning

Include: type, usage, and hours of occupancy of building or structure, number of occupants and types(s) of activity, area and volume of materials in conditioned space, building orientation, types of shade and glass exterior cladding, ventilation requirements, amount and type of artificial light and hours of use.

Heat Gains in Building

Heat lost during cold seasons must be made up for by the heating system; in summer, heat gained through conduction, convection, and radiation must be removed through the air-conditioning system.

Heat Sources in Buildings

Heat transmitted through walls, roofs, floors, partitions, ceilings, and glass, owing to differences between indoor and outdoor temperature differences, Heat from solar radiation striking upon the exterior surfaces of walls and glass, absorbed by them and conducted through the interior, Heat carried in by infiltrating or outside air, Heat given off from occupants, Heat given off by lights, cooking devices, motors, fans, and industrial processes within the conditioned space.

Cooling Load Calculation Factors

Include Internal loads: From lights, occupants, equipment, and the like. Thermal transmission loads: Heat transferring from walls, doors, floors, ceilings, etc. Infiltration and ventilation load: Entry of outside air into the space to be conditioned; outside air affects both temperature and humidity levels in the space to be conditioned. Solar load: Heat gained due to the heat energy incident on the surface. Depends upon the characteristics of the surface.

Unitary/Room Air-Conditioner

A self-contained unit which houses all the necessary air-conditioning components, such as the compressor, condenser, and evaporator, in the same cabinet.

Split-type Air-Conditioner

A type of air-conditioning system composed of two separate sections, one installed inside the room (the fan coil unit), while the other is mounted outside the building (air-cooled condensing unit).

Package/Cabinet-type Air Conditioning System

A type of split-type air-conditioning unit secured within a bigger housing. Often used in public establishments in need of constant air-conditioning.

Centralized Air Conditioning System

A type of integrated air-conditioning system used for building installation using ducts.

Compressor (Air-Conditioning System Component)

A Unitary-type component

Condenser coil (Air-Conditioning System Component)

A Unitary-type component

Evaporator coil (Air-Conditioning System Component)

A Unitary-type component

Expansion valve (Air-Conditioning System Component)

A Unitary-type component

Thermostat (Air-Conditioning System Component)

A Unitary-type component

Controls (Air-Conditioning System Component)

A Unitary-type component

Fan/blower (Air-Conditioning System Component)

A Unitary-type component

Filter (Air-Conditioning System Component)

A Unitary-type component

Fan (FCU)

A component of Fan Coil Unit (FCU)

Coil (FCU)

A component of Fan Coil Unit (FCU)

Filter (FCU)

A component of Fan Coil Unit (FCU)

Fan Coil units (FCU)

Can be placed in horizontal or vertical positions.

Coil cooling for FCU

Can be cooled either by use of chilled water or by direct expansion refrigeration.

Unitary (room) – type air-conditioner

The unit is the indoor portion

Air Purity

Component of air conditioning, removal of contaminants.

Air Motion

Component of air conditioning, ensuring proper circulation.

Heat Transmission

Movement of thermal energy.

Heating System

Compensates for heat lost during cold seasons.

Air Flow

Important consideration for air-conditioning standards.

Air Supply

Important consideration for air-conditioning standards.

Volatile Refrigerant

Used in mechanical refrigeration with low boiling point.

Water Chiller

The absorption machine is one form.

Heat Transfer

A factor in cooling load calculations from walls, doors, etc.

Outside Air

Affects temperature and humidity levels in cooling load calculations.

Surface Characteristics

Impacts solar load in cooling load calculations.

Integrated Air-Conditioning

A centralized air conditioning system is a type utilized for building installations using ducts.

Effective Temperature

Maintained range for comfortable cooling is 68 - 74°F.

Occupant Activity

A design consideration in air conditioning.

Building Orientation

A design consideration in air conditioning.

Equipment

Internal loads from this must be considered in cooling load calculation.

Infiltration

Entry of outside air into a conditioned space.

Solar Radiation

Heat load from this striking exterior surfaces.

Indoor Comfort

Regulation of environmental factors to provide.

Coolant Vapor

Created during the evaporation stage of absorption cooling.

Artificial Light

Source of heat gain in conditioned spaces.

Human Occupancy

Essential consideration in air conditioning standards

Thermal Energy

Another name used to describe Heat.