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A
The ACCA Connection (see: HVAC Designs)
Right-J8 and Right-JD are recognized by ACCA as their official software versions of the Manual J and Manual D calculation and sizing methods.
What is ACCA? (see: HVAC Designs)
The Air Conditioning Contractors of America (ACCA) is a nonprofit trade association of HVACR contractors with national headquarters located in Washington D.C. With over 3,400 members and more than 50 local chapters across the country, ACCA’s membership includes manufacturers of HVAC equipment, utilities, equipment wholesalers and distributors, vocational and technical schools and others.
ACCA represents and serves contractors who design, install, service and repair air conditioning, heating, refrigeration, humidification, dehumidification, air purification and ventilation systems. ACCA is dedicated to providing its members with the tools and information for managing quality in their business operations through numerous education programs, publications, and technical and management reference libraries.
In addition, ACCA vigorously promoted the interests and concerns of its members to the US Congress and federal agencies and encourages input and participation from members in the association’s goal to influence public policy to improve the HAVC business climate.
Air change
The amount of outdoor air required to completely replace the air in a room or building with outdoor air, by air leakage (infiltration) and/or through an engineered ventilation system.
Air changes per hour
The number of times per hour the total volume of indoor air contained in a room or building is replaced with outdoor air by infiltration or mechanical ventilation.
Air conditioner
An assembly of equipment for the simultaneous control of air temperature, relative humidity, purity and motion.
Air Conditioning System (see: HVAC Designs)
A system that consists of air exchangers, blowers, filters, supply and return-air systems, and shall include any apparatus installed in connection therewith.
Air Conditioning Contractors of America (ACCA) (see: HVAC Designs)
A nonprofit trade association of HVACR contractors. (See the end of this Glossary)
Airflow
The movement of air, usually within boundaries such as ducts.
Air outlet
A device or opening through which air is withdrawn from or discharged into a conditions space.
Air Volumetric Flow (AVF)
Refers to the air flow rate through an HVAC unit or duct system. Measured in cubic feet per minute (cfm).
Annual fuel consumption
The amount of fuel used in one year.
Annual fuel utilization efficiency (AFUE) (see: HVAC Designs)
An annual fuel efficiency rating similar to mileage ratings for cars. The higher the ARUE for a furnace, the more efficient the furnace. All furnace models are tested using U.S. Department of Energy procedures to assign their AFUE rating.
Ambient Air
The air surrounding an object (usually outdoor air or the air in an enclosure under study). American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). An international organization that is organized for the sole purpose of advancing the arts and sciences of heating, ventilation, air conditioning and refrigeration for the public’s benefit through research, standards writing, continuing education and publications. Boiler (Residential) – A self contained appliance from which water is heated by any number of fuels. The heated water is circulated for heating purposes and then returned to the boiler, and which operates at water pressure not exceeding 30 pounds per square inch and water temperatures not exceeding 250.
B
Boiler (see: HVAC Designs)
A container or vessel in which a liquid is heated using any heat source.
Building Thermal Envelope
The basement walls, exterior walls, floor, roof, and any other building element that enclose conditioned spaces.
C
Ceiling Height - level and flat
Measurement from floor to ceiling. Cathedral – measurement from floor to lowest point and floor to highest point.
Chimney
A primarily vertical structure containing one or more flues, for the purpose of carrying gaseous products of combustion and air from a fuel-burning appliance to the outside atmosphere.
Chimney Connector
A pipe that connects a fuel-burning appliance to a chimney. Also called a vent.
Chimney Types
Residential-type appliance. An approved chimney for removing the products of combustion from fuel-burning, residential-type appliances producing combustion gases not in excess of 1,000_F under normal operating conditions, but capable of producing combustion gases of 1,400_F during intermittent forced firing for periods up to 1 hour. All temperatures shall be measured at the appliance flue outlet. Residential-type appliance chimneys include masonry and factory-built types.
Cooling
The process for reducing the temperature of a space of system below a specified level.
Cooling load temperature difference
Used to calculate the heat gain for walls, ceilings, floors and opaque doors. A CLTD represents the effective air temperature difference across the structural panel. This temperature difference accounts for the air-to-air temperature difference across the panel, the heating effect of the sun striking the outdoor surface of the panel and the thermal mass of the panel.
Cooling in side dry-bulb
The temperature used to set the thermostat during the cooling season.
Cold Wall
Any wall that faces an unconditioned area but is not an outside wall. Example: an unconditioned garage.
Combustion Air
The air provided to fuel-burning equipment including air for fuel combustion, draft hood dilution and ventilation of the equipment enclosure.
Condensate
The liquid that separates from a gas due to a reduction in temperature, e.g., water that condenses from flue gases and water that condenses from air circulating through the cooling coil in air conditioning equipment.
Condensing Appliance
An appliance that condenses water generated by the burning of fuels.
Conditioned Area
That area within a building provided with heating and/or cooling systems or appliances capable of maintaining, through design or heat loss/gain, a comfortable environment during the heating/cooling season and/or has a fixed opening directly adjacent to a conditioned area.
Conditioned Area
An area which is either heated or cooled by mechanical means.
Conditioned Floor Area
The horizontal projection of the floor associated with the conditioned space.
Condition Floor Space
For energy purposes, space within a building that is provided with heating and/or cooling equipment or systems capable of maintaining, through design or heat loss/gain, 50_F during the heating season and 85_ during the cooling season, or communicates directly with a conditioned space. For mechanical purposes, an area, room or space being heated or cooled by any equipment or appliance.
Construction Documents Design
Written, graphic and pictorial documents prepared or assembled for describing the design, location and physical characteristics of the elements of a project necessary for obtaining a building permit or calculating a heat loss/gain. Construction drawings shall be drawn to an appropriate scale.
Control, Limit
An automatic control responsive to changes in liquid flow or level, pressure, or temperature for limiting the operation of an appliance.
Control, Primary Safety
A safety control responsive directly to flame properties that senses the presence or absence of flame and, in event of ignition failure or unintentional flame extinguishments, automatically causes shutdown of mechanical equipment.
Convector (see: HVAC Designs)
A system incorporating heating elements in an enclosure in which air enters an opening below the heating element, is heated and leaves the enclosure through an opening located above the heating element. Example: copper fin-tube baseboard heat
Cubic feet per minute (cfm) (see: HVAC Designs)
The volume of air that can be heated or cooled by heating or cooling equipment per minute.
D
Damper, Volume
A device that will restrict, retard or direct the flow of air in any duct, or the products of combustion of heat-producing equipment, vent connector, vent or chimney.
Design (see: HVAC Designs)
As provided by “"air comfort designs"” (also known in the technical field as a heat loss/gain)– A document assembled for the purpose of determining the correct size of heating and/or air conditioning equipment and/or the correct amount of distribution piping or ductwork to condition a structure. The “design” is calculated using Right-J8 and Right-D which is recognized by ACCA (The Air Conditioning Contractors of America) as their official software versions of the Manual J and Manual D calculation and sizing methods. The “design” would list each room of the structure showing the amount of BTU’s and related output means to properly condition a room and collectively the structure. The necessary information such as window and door sizes, room sizes, ceiling heights, outside wall dimensions, insulation effectiveness and quantities, climate, direction that walls face, interior design temperature, type of heat and type of fuel are used to attain this calculation. The “design” is primarily used as a sizing tool for any new, additional, supplemental or replacement heating or air conditioning project. A “design” is also required in many municipalities of the country to acquire a permit before proceeding with a new project.
Design/Layout (see: HVAC Designs)
A “design” with the addition of a scaled floor plan showing the complete single or multiple story structure with the heating/air conditioning equipment. All main supply and return ductwork and branches are shown sized to scale and color coded. A complete material list is supplied with an option for pricing. A “design/layout” is compiled as a presentation ready for a customer or installer to review (Contractor, HVAC Distributor), ready for a contractor to estimate from (Homeowner) or ready for a trip to the supply house (DIY).
Design airflow
The required airflow when the system is operating under assumed maximum conditions of design.
Design conditions
The specified environmental conditions, such as temperature and humidity, required to be produced and maintained by a system.
Design Professional
An individual who is registered, licensed or certified to practice their respective design profession as defined by the requirements of the registration laws of the state, city, or jurisdiction.
Design swing
The temperature rise allowed above the inside design temperature.
Direct-Vent Appliance
A fuel-burning appliance with a sealed combustion system that draws all air for combustion from the outside atmosphere and discharges all flue gases to the outside atmosphere.
Draft
The pressure difference existing between the appliance or any component part and the atmosphere that causes a continuous flow of air and products of combustion through the gas passages of the appliance to the atmosphere.
- Induced draft
The pressure difference created by the action of a fan, blower or ejector that is located between the appliance and the chimney or vent termination.
- Natural draft
The pressure difference created by a vent or chimney because of its height, and the temperature difference between the flue gases and the atmosphere.
Dry-bulb temperature
Air temperature measured by an ordinary thermometer when there is no solar heating effect or evaporative cooling effect.
Duct sizing (see: HVAC Designs)
The calculation of dimensions of ducting for a given air distribution system
Duct System (see: HVAC Designs)
A continuous passageway for the transmission of air, which, in addition to ducts, includes duct fittings, dampers, plenums, fans and accessory air-handling equipment and appliances.
E
Efficiency
The ratio of useful output energy of a piece of equipment to input energy.
Energy-efficiency ratio (EER)
The ratio of net cooling capacity in Btuh to the total rate of electric input in watts, under designated operating conditions.
Equipment
All piping, ducts, vents, control devices and other components of systems other than appliances that are permanently installed and integrated to provide control of the environmental conditions for buildings.
Equipment sizing load
Also called design heating or cooling load.
Equivalent length
A method of expressing the friction loss of duct firings by equating the firing loss to straight duct friction loss.
Exterior Wall
An above-grade wall enclosing conditioned space. Includes between floor joists, peripheral edges of floors, roof and basement knee walls, dormer walls, gable end walls, walls enclosing a mansard roof, and basement walls with an average below grade wall area that is less than 50 percent of the total opaque and non opaque area of the enclosing side.
F
Fahrenheit temperature (F)
The temperature scale on which at standard atmospheric pressure, the boiling point of water is 212 _F and its freezing point is 32_F: absolute zero is –459.69_F.
Fenestration
Skylights, roof windows, vertical windows (whether fixed or moveable); opaque doors; glazed doors; glass block; and combination opaque/glazed doors.
Fireplace
An assembly consisting of hearth and fire chamber of noncombustible material and provided with a chimney, for use with solid fuels.
Factory-built fireplace
A listed and labeled fireplace and chimney system composed of factory-made components, and assembled in the field in accordance with manufacturer’s instructions and the conditions of the listing.
Forced air (see: HVAC Designs)
A distribution system in which a fan circulates air from a heating or cooling unit to rooms through a network of ducts.
Forced-draft venting system
A portion of a venting system using a fan or other mechanical means to cause the removal of flue or vent gases under positive static pressure.
Fireplace Stove
A freestanding, chimney-connected solid-fuel burning heater designed to be operated with the fire chamber doors in either open or closed position.
Floor Furnace
A self-contained furnace suspended from the floor of the space being heated, taking air for combustion from outside such space, and with means for lighting the appliance from such space.
Floor plan (see: HVAC Designs)
The drawing of a structure with the view from overhead looking down. The drawing would include exterior and interior walls, windows, doors, skylights, and staircases. “air comfort designs” floor plan also shows colored lines depicting a furnace, ductwork, registers and related equipment or a boiler and related piping and heat.
Flue Gases
Products of combustion plus excess air in appliance flues or heat exchangers.
Friction rate
The pressure loss that occurs between two points in duct system.
Fuel-Piping System
All piping, tubing, valves and fittings used to connect fuel utilization equipment to the point of fuel delivery.
Furnace
A vented heating appliance designed or arranged to discharge heated air into a conditioned space or through a duct or ducts.
G
Gas Appliance Manufactures Association
A national trade association whose members manufacture appliances, components and related products used in connection with space heating water, water heating and commercial food service. In addition to gas-fired appliances, GAMA’s scope includes certain oil-fired and electrical appliances. GAMA’s principal purpose is to serve and represent its members and the industries, which they comprise
Ground-Source Heat Pump Loop System
Piping buried in horizontal or vertical excavations or placed in a body of water for the purpose of transporting heat transfer liquid to and from a heat pump. Included in this definition are closed loop systems in which the liquid is re circulated through open loop systems in which the liquid is drawn from a well or other source.
H
Habitable Space
A space in a building for living, sleeping, eating or cooking. Bathrooms, toilet rooms, closets, halls, storage or utility spaces and similar areas are not considered habitable spaces.
Heat gain (see: HVAC Designs)
The amount of heat gained and measured in BTU’s from a space to be conditioned, at the summer outdoor design temperature and a specified indoor design condition.
Heat flow
The passage of heat from one point to another or one space to another by one or more of the three modes (conduction, convection and radiation).
Heat loss (see: HVAC Designs)
The amount of heat lost and measured in BTU’s from a space to be conditioned, at the winter outdoor design temperature and a specified indoor design condition.
Heat Pump (see: HVAC Designs)
An appliance having heating or heating/cooling capability and that uses refrigerants to extract heat from air, liquid or other sources.
Heat transfer multiplier (HTM) – The amount of heat that flows through one square foot of a building component at a given temperature difference. HTM values differ for various wall constructions. Heating HTM’s for doors, walls, etc. are determined by multiplying the transmission coefficient (U) by the winter design temperature difference. Cooling HTM’s for doors, walls, etc. are determined by multiplying the transmission coefficient (U) by the summer equivalent temperature difference.
Heating
The process of adding heat energy causing a raise in temperature, or a transfer of sensible heat into latent heat.
Heating inside dry-bulb
The temperature used to set the thermostat during the heating season.
Heating load
The heating rate required to replace heat loss from the space being controlled.
Heating seasonal performance factor
The ratio of the total heat delivered over the heating seasons (not to exceed 12 months) to the total energy input over the heating season, in consistent units.
Heating, Ventilation and Air Conditioning (HVAC)
Heating, Ventilation, Air Conditioning and Refrigeration (HVACR)
Hour
One of the points on a timepiece marking off 12 or 24 successive intervals of 60 minutes, from midnight to noon and noon to midnight to midnight.
Humidity ratio
The ratio of the mass of water vapor to the mass of dry air.
Hydronic
Commonly called hot water or steam heat. Hot water heating uses a boiler to heat water with any fuel. The heated water is then circulated throughout a distribution piping system using either gravity or a circulator and released into the conditioned area though radiation or convection. Hot water is common in residential and commercial buildings. Steam heat uses a boiler to heat water with any fuel. The water is heated to produce steam in the boiler and pressure pushes the steam from the boiler through distribution piping to the final release point. Steam heat is commonly used in commercial and industrial applications.
K
Kilowatt hour (kWh) (see: HVAC Designs)
The energy unit used in marketing electrical power (the SI unit for energy is the joule (J))
L
Latent gain
The additional load caused by humidity reduction. Affected by the relative humidity.
Latent heat
Energy (heat) associated with a change of state, as of liquid to vapor or vice versa, expressed a Btu/lb. In HVAC usage, the energy associated with the moisture in the air.
Latent infiltration Load
The heat gain or latent load from moisture brought in with the air leakage.
Latent ventilation Load
The latent gain caused by mechanical ventilation equipment.
Length
A measure used as a unit to estimate dimensions.
Linear foot
A unit of length in the U.S. Customary and British Imperial systems equal to 12 inches (0.3048 meter).
Listed And Listing
Terms referring to equipment that is shown in a list published by an approved testing agency qualified and equipped for experimental testing and maintaining and adequate periodic inspection of current productions and whose listing states that the equipment complies with nationally recognized standards when installed in accordance with the manufacturer’s installation instructions.
Living Space
Space within a dwelling unit utilized for living, sleeping, eating, cooking, bathing, washing, and sanitation purposes.
Load calculation (see: HVAC Designs)
Determines how much energy (Btu) is required to maintain cooling, heating, and ventilation.
M
Masonry chimney
A field-constructed chimney comprised of solid masonry units, bricks, stones or concrete.
Masonry fireplace
A field-constructed fireplace composed solid masonry units, bricks, stones or concrete.
Manual D (see: HVAC Designs)
ACCA’s method for sizing residential ductwork. Right-Suite Residential is the computerized version of Manual D.
Manual J (see: HVAC Designs)
ACCA’s method for sizing residential load calculations. Right-Suite Residential is the computerized version of Manual J.
Mechanical System
A system specifically addressed and regulated by code and composed of components, devices, appliances and equipment.
Mechanical Draft System
A venting system designed to remove flue or vent gases by mechanical means to cause the removal of flue or spent gases under non positive static vent pressure.
Multi zone (or multiple zone) system (see: HVAC Designs)
For dwellings, a comfort-conditioning system designed to serve two or more rooms or areas having different or unsynchronized heating and cooling requirements. In some cases a zone is required to satisfy a special humidification, filtration or ventilation requirement.
N
Natural Draft System
A venting system designed to remove flue or vent gases under non positive static vent pressure entirely by natural draft.
Non conditioned Space
A Space that does not have insulated walls, floors or ceilings and has no means for heating or cooling.
O
Outdoor air
The air outside a building or taken from outdoors and not previously circulated through the system.
Outside air
External air; atmosphere exterior to refrigerated or conditioned space; ambient, surrounding air.
Outside Wall
Any wall that directly faces the outdoors.
P
Power venting system
A portion of a venting system using a fan or other mechanical means to cause the removal of flue or vent gases under positive vent pressure.
R
R-value (see: HVAC Designs)
Thermal resistance value of an insulator. Higher R-values mean better insulation and lower heat flow. R-values are expressed in ft_. U/Btuh.
Radiation gain
Heating increases due to the radiation effects from the sun. Surfaces transfer heat.
Radiant heat (see: HVAC Designs)
Heat that passes through the air, heating solid objects that in turn heat the surrounding area.
Refrigerant Compressor
A specific machine, with or without accessories, for compressing a given refrigerant vapor.
Relative humidity
Approximately, the ratio of the density of the water vapor in the air to the saturation density of water vapor at the same temperature swing and equipment rating conditions
Return Air (see: HVAC Designs)
Air removed from an approved conditioned space or location and re circulated through the heating or cooling appliance.
Room Heater
A freestanding heating appliance installed in the space being heated and not connected to ducts.
S
Seasonal Energy efficiency ratio (SEER) (see: HVAC Designs)
The total cooling output of an air conditioner during its normal annual usage period for cooling, in Btuh divided by the total electric energy input during the some period, in watt-hours.
Sensible gain
The increase in temperature where moisture is not involved.
Solar gain
Heat gain into a building form the solar radiation through glass of different types and interior shading. Also called “radiation gain”.
Static pressure
The force per unit area, perpendicular to the direction of flow in a duct.
Story Above Grade
Any story having its finished floor surface entirely above grade, except that a basement shall be considered as a story above grade where the finished surface of the floor above the basement is:
- More than 6 feet above grade plan.
- More than 6 feet above the finished ground level for more than 50% of the total building perimeter.
- More than 12 feet above the finished ground level at any point.
Supply Air (see: HVAC Designs)
Air delivered to a conditioned space through ducts or plenums from the heat exchanger of a heating, cooling or ventilating system.
T
Temperature difference
The variation between the inside and outside air temperature. For cooling temperature difference, solar gain data is considered.
Thermal Resistance, R-Value (see: HVAC Designs)
The inverse of the time rate of heat flow through a body from one of its bounding surfaces to the other for a unit temperature difference between the two surfaces, under steady state conditions, per unit area.
Thermal Transmittance, U-Factor (see: HVAC Designs)
The coefficient of heat transmission through a building envelope component or assembly, equal to the time rate of rate flow per unit. Temperature difference between the warm side and cold side air films.
Ton (see: HVAC Designs)
A time-rate of cooling equal to 12,000Btuh (approximately 3517 W).
Total latent load (see: HVAC Designs)
The sum of the following latent loads: internal gains, ventilation, and infiltration.
Total sensible gain (see: HVAC Designs)
The total of all sensible gains for a room, including internal gains. Infiltration and duct gains.
Transmission loss
Heating or cooling loss through a solid surface, such as a wall. (This differs from infiltration loss, which is the heating or cooling loss through the air).
U
U-value (or U Factor) (see: HVAC Designs)
Combines the effect of the thermal resistance of the wall, ceiling/roof, or glass, and the effects of convection at the same inside and outside surfaces. U values are expressed in Btuh/sq ft F
Unconditioned Area
An area, which is protected from the outdoor elements by the building envelope but has no mechanical means of heating or cooling.
Unusually Tight Construction
Construction in which:
- Walls and ceilings comprising the building thermal envelope have a continuous water vapor retarder with a rating of 1 perm or less with openings therein gasket ed or sealed.
- Storm windows or weather-stripping is applied around the threshold and jambs of opaque doors and open able windows.
- Caulking or sealants are applied to areas such as joints around window and doorframes between sole plates and floors, between wall-ceiling joints, between wall panels, at penetrations for plumbing, electrical and gas lines, and at other openings.
V
Ventilation
The natural or mechanical process of supplying conditioned or unconditioned air to or removing such air from, any space.
Venting
Removal of combustion products to the outdoors.
Venting System
A continuous open passageway from the flue collar of an appliance to the outside atmosphere for the purpose of removing flue or vent gases. A venting system is usually composed of a vent or a chimney and vent connector, if used, assembled to form the open passageway.
W
Wet-bulb temperature
The temperature indicated by a wet-bulb psychrometer. It is a good indicator of the amount of moisture on the air. When the wet-bulb temperature is equal to the dry-bulb temperature, the relative humidity is 100%.
Z
Zone (see: HVAC Designs)
An area in a building that is isolated by a full partition. A building can have several zones. You can adjust the temperature in one zone independently of the other zones. The number of zones in a house is equal to the number of thermostats in the house.
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