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AIR CONDITIONING & HEAT PUMP SYSTEMS

A/C - HEAT PUMP CONTROLS & SWITCHES
A/C DATA TAGS
A/C - HEAT PUMP CRITICAL DEFECTS
A/C DIAGNOSTIC FAQs
A/C REFRIGERANTS
A/C TYPES, ENERGY SOURCES

AGE of AIR CONDITIONERS & HEAT PUMPS
AGE of HEATERS, BOILERS, FURNACES
AGE of WATER HEATERS
AIR CONDITIONER BTU CHART
AIR CONDITIONER COMPONENT PARTS
AIR CONDITIONER TYPES, ENERGY SOURCES
AIR CONDITIONER NOT WORKING

AIR FILTERS for HVAC SYSTEMS

AIR HANDLER / BLOWER UNITS
ANIMAL ALLERGENS / PET DANDER
ANIMAL ENTRY POINTS in buildings
ANIMAL ODORS IN buildings
APPLIANCE EFFICIENCY RATINGS
ASBESTOS IDENTIFICATION IN buildings

BACKUP HEAT for HEAT PUMPS

BLOWER DOORS & AIR INFILTRATION
BLOWER FAN CONTINUOUS OPERATION
BLOWER FAN OPERATION & TESTING

BOOKSTORE - Air Conditioning "How To" Books

CAPACITORS for HARD STARTING MOTORS
CAPILLARY TUBES
CLEANING & Legionella BACTERIA
CHINESE DRYWALL HAZARDS
COMBUSTION GASES & PARTICLE HAZARDS

COMPRESSOR & CONDENSING COIL, A/C

CONDENSATE HANDLING, A/C
CLEANING & Legionella BACTERIA
DUCT SYSTEM & DUCT DEFECTS
  AIR FILTERS for HVAC SYSTEMS
  ALLOY SYSTEMS FLEXDUCT
  ASBESTOS HVAC DUCTS
  ASBESTOS PAPER on DUCTWORK
  ASBESTOS TRANSITE DUCTWORK
  BALANCING AIR DUCT FLOW
  DUCT & AIR HANDLER ODORS
  DUCT DAMAGE, MECHANICAL
  DUCT INSULATION - Asbestos Paper
  DUCT ROUTING & SUPPORT
  DUST CONTAMINATION FROM HVAC?
  FIBERGLASS DUCT, RIGID CONSTRUCTION
  FIBERGLASS HVAC DUCTS
  FIRE DAMPERS in DUCTWORK
  FLOOD DAMAGE in DUCT WORK
  GOODMAN GRAY FLEXDUCT
  INCREASING RETURN AIR
  LEAKY DUCT CONNECTIONS
  LOCATION OF REGISTERS & DUCTS
  MOLD in AIR HANDLERS & DUCT WORK
  NOISES in DUCT SYSTEM
  ODORS in AIR HANDLERS & DUCT WORK
  OWENS CORNING FLEXDUCT
  OWL FLEXDUCT
  RETURN AIR REGISTERS & DUCTS
  SOUNDPROOFING for DUCTWORK
  SUPPLY DUCTS & REGISTERS
  TRANSITE PIPE AIR DUCTS
  UNDERSIZED RETURN DUCTS
  UNSAFE DUCT OPENINGS
  VIBRATION DAMPENERS
  WATER & ICE IN DUCT WORK
  WET CORRODED DUCT WORK
  ZONE DAMPER CONTROLS

DUST CONTAMINATION FROM HVAC?

EDUCATION, HVAC SCHOOLS
ELECTRIC MOTOR DIAGNOSTIC GUIDE
ELECTRIC MOTOR OVERLOAD RESET SWITCH
ELECTRICAL POWER SWITCH FOR HEAT

ENERGY SAVINGS in buildings
EVAPORATIVE COOLING SYSTEMS
EVAPORATOR COIL or COOLING COIL
EXPANSION VALVES, REFRIGERANT

FAN, AIR HANDLER BLOWER UNIT
FAN AUTO ON Thermostat Switch
FAN CONVECTOR HEATERS - HYDRONIC COILS
FAN LIMIT SWITCH
FAN NOISES

FURNACES WARM AIR HEATING SYSTEMS

GASES, EXPOSURE, TESTING
  Carbon Dioxide - CO2
  Carbon Monoxide - CO
  METHANE GAS SOURCES
GAS MEASUREMENT TOOLS
GAUGE, REFRIGERATION PRESSURE TEST

HEAT LOSS (or GAIN) in buildings
HEAT LOSS (or GAIN) INDICATORS
HEAT LOSS R U & K VALUE CALCULATION

HEAT PUMPS
HEATING SMALL LOADS
HOUSEWRAP AIR & VAPOR BARRIERS

HUMIDITY LEVEL TARGET

INDOOR AIR QUALITY IMPROVEMENT GUIDE

INSPECTION CHECKLIST - OUTDOOR UNIT
INSPECTION LIMITATIONS
LEED GREEN BUILDING CERTIFICATION

LOST COOLING CAPACITY

MANUALS & PARTS GUIDES - HVAC
MOTOR OVERLOAD RESET SWITCH
MOLD in AIR HANDLERS & DUCT WORK

ODORS in AIR HANDLERS & DUCT WORK
OPERATING COST
OPERATING DEFECTS
OPERATING TEMPERATURES

NOISY AIR CONDITIONER / HEAT PUMP
NOISE / SOUND DIAGNOSIS & CURE
  Air Leak Noises
  AIR CONDITIONING & HEAT PUMP NOISES

PORTABLE ROOM AIR CONDITIONERS
PRESSURE READINGS, REFRIGERANT

REPAIR GUIDE, AIR CONDITIONERS / HEAT PUMPS
REPAIR & DIAGNOSTIC FAQs for A/C

REFRIGERANTS
RETROFIT SIZING for A/C or HEAT PUMPS

SEER RATINGS & OTHER DEFINITIONS
  SEER RATING HISTORY

SOLAR ENERGY SYSTEMS

SPLIT SYSTEM AIR CONDITIONERS & HEAT PUMPS
SWAMP COOLERS
SYSTEM OPERATION
  OPERATING CONTROLS
  SAFETY CONTROLS

THERMOSTATS, HEATING / COOLING
THERMOSTATIC EXPANSION VALVES

WATER COOLED AIR CONDITIONERS

More Information

Photograph of commercial air conditioning system ceiling plenum with debris

Guide to Balancing Heating & Air Conditioning Air Flow in buildings
InspectAPedia®  -         

  • Heating & Air Conditioning Air Flow Balancing Advice
  • Questions & Answers about balancing air delivery or air supply in duct systems for heating and air conditioning
  • Air Conditioning (or Heating) Duct Defects

This HVAC ductwork diagnosis and repair article describes proper (and improper) balancing of heating & air Conditioning duct air flow in residential buildings and in commercial office space including high-rise buildings.

InspectAPedia offers impartial, unbiased advice without conflicts of interest. We will block advertisements which we discover or readers inform us are associated with bad business practices, false-advertising, or junk science. Our contact info is at InspectAPedia.com/Contact.htm.

© Copyright 2012 InspectAPedia.com, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use page top links to major topics or use links at the left of each page to navigate within topics and documents at this website. Green links show where you are in a document series or at this website.

Balancing Air Ducts for Proper Warm or Cool Air Delivery

Look for indications that the system has not been balanced for optimum air flow:

  • Uneven temperatures throughout the air conditioned space, room to room, or within rooms, when the system is operating
  • All registers are open but airflow varies widely from register to register

You may want your service person to review air flow in different rooms, to add manual balancing dampers in the duct system (and show you where they are located and mark on the duct just where the balancing damper levers are normally set.

Air conditioning cool air balancing in offices & commercial spaces

Location of Air Supply and Air Return Registers in Commercial buildings

Photograph of commercial air conditioning duct system registers Photograph of lifted ceiling tile subverting air conditioning system air flow

The photographs above show both supply and return ceiling registers in a commercial office space. In this case they are located too close together. The second photograph shows that a ceiling tile has been removed from a suspended ceiling over an office which uses the ceiling cavity as a common return air plenum. While this may produce more airflow in the office where this suspended ceiling tile was removed, it has unbalanced the entire air conditioning system for the rest of the offices in the building.

Many commercial spaces and offices are cooled (and sometimes heated as well) by an air handler which delivers supply air to each office area by flex duct connected to ceiling registers.

Return air is passed back to the air handler through the large common space above a suspended ceiling over the occupied space. Special vents either around the supply registers or placed separately are intended to pass return air to the common ceiling space, and their location and adjustment are important to provide balanced airflow in the work space.

Debris & Contaminants in Ceilings

Photograph of commercial air conditioning system ceiling plenum with debris

This photograph shows a common ceiling plenum over a commercial office space in a Manhattan high rise building. Notice the considerable amount of debris atop the ceiling tiles?

All of the office conditioned air moves through this area, risking additional levels of irritating or harmful particles, particularly if the debris contains asbestos fragments or lead paint chips. (In this particular case tests showed that this was not the case.)

Here are some common concerns or defects in commercial installations that use this design:

  • Missing ceiling tiles: People in individual offices subvert the system by seeking more or less cool air by removing suspended ceiling tiles. These un-planned openings make it impossible for the system to be properly balanced.
  • Common return air plenum Use of the ceiling space as a giant return plenum above the work area means that any debris, mold (perhaps from roof leaks), fiberglass, asbestos, or other problematic particles that are in this space are readily circulated through the building air

Photograph of commercial air conditioning system ceiling plenum with debris Photograph of commercial air conditioning system ceiling plenum with debris

These photos show a common ceiling return air plenum over commercial offices. In the first or left hand photo, notice that rectangular opening in the distance? The second photo is a closeup. Openings had been left open between the office space and the top floor hallway and also between the hallway and other office spaces in the building, so that particles, leak-related mold, or other irritating particles developing over any office will be shared among all of the tenants on this building floor.

  • Missing or incomplete ceiling partitioning in large commercial buildings may mix air (and odors or contaminants) from multiple offices or building use areas, redistributing these un-wanted odors or particles to other building areas. One of our clients who maintained a law office in a strip mall complained of chemical odors which were traced to a beauty parlor located at the extreme other end of the building.
Photograph of commercial air conditioning system subverted by open window

 

Open windows, especially in a tall office building such as shown by this photograph, cause a tremendous up-draft through the building, moving particles, gases, or other potential IAQ concerns up through the building.

In this instance the office occupants on the 18th floor of this Manhattan office opened their windows and also their office entry door to try to cool off their offices because they were unable to turn off the building heating radiators.

Questions & Answers regarding this article

Questions & Answers about balancing air delivery or air supply in duct systems for heating and air conditioning

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Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

AIR CONDITIONING & HEAT PUMP SYSTEMS
AIR CONDITIONER COMPONENT PARTS
A/C - HEAT PUMP CONTROLS & SWITCHES
A/C - HEAT PUMP CRITICAL DEFECTS
A/C DIAGNOSTIC FAQs
A/C TYPES, ENERGY SOURCES
A/C REFRIGERANTS

AIR CONDITIONER BTU CHART
SEER RATINGS & OTHER DEFINITIONS
OPERATING COST
SYSTEM OPERATION
OPERATING TEMPERATURES
OPERATING DEFECTS
LOST COOLING CAPACITY
CHINESE DRYWALL HAZARDS
COMBUSTION GASES & PARTICLE HAZARDS
CONDENSATE HANDLING, A/C
CONDENSATION or SWEATING PIPES, TANKS
COMPRESSOR & CONDENSING COIL, A/C
AIR FILTERS for HVAC SYSTEMS

AIR HANDLER / BLOWER UNITS
ANIMAL ALLERGENS / PET DANDER
ANIMAL ENTRY POINTS in buildings
ANIMAL ODORS IN buildings
APPLIANCE EFFICIENCY RATINGS
ASBESTOS IDENTIFICATION IN buildings

BACKUP HEAT for HEAT PUMPS

BLOWER DOORS & AIR INFILTRATION
BLOWER FAN CONTINUOUS OPERATION
BLOWER FAN OPERATION & TESTING

BOOKSTORE - Air Conditioning "How To" Books

CAPACITORS for HARD STARTING MOTORS
CAPILLARY TUBES
CLEANING & Legionella BACTERIA
CHINESE DRYWALL HAZARDS
COMBUSTION GASES & PARTICLE HAZARDS

COMPRESSOR & CONDENSING COIL, A/C

CONDENSATE HANDLING, A/C
BACKUP HEAT for HEAT PUMPS

BLOWER DOORS & AIR INFILTRATION
BLOWER FAN CONTINUOUS OPERATION
BLOWER FAN OPERATION & TESTING

BOOKSTORE - Air Conditioning "How To" Books

CAPACITORS for HARD STARTING MOTORS
CAPILLARY TUBES
CLEANING & Legionella BACTERIA
DUCT SYSTEM & DUCT DEFECTS
  AIR FILTERS for HVAC SYSTEMS
  ALLOY SYSTEMS FLEXDUCT
  ASBESTOS HVAC DUCTS
  ASBESTOS PAPER on DUCTWORK
  ASBESTOS TRANSITE DUCTWORK
  BALANCING AIR DUCT FLOW
  DUCT & AIR HANDLER ODORS
  DUCT DAMAGE, MECHANICAL
  DUCT INSULATION - Asbestos Paper
  DUCT ROUTING & SUPPORT
  DUST CONTAMINATION FROM HVAC?
  BALANCING AIR DUCT FLOW
  FIBERGLASS DUCT, RIGID CONSTRUCTION
  FIBERGLASS HVAC DUCTS
  FIRE DAMPERS in DUCTWORK
  FLOOD DAMAGE in DUCT WORK
  GOODMAN GRAY FLEXDUCT
  INCREASING RETURN AIR
  LEAKY DUCT CONNECTIONS
  LOCATION OF REGISTERS & DUCTS
  MOLD in AIR HANDLERS & DUCT WORK
  NOISES in DUCT SYSTEM
  ODORS in AIR HANDLERS & DUCT WORK
  OWENS CORNING FLEXDUCT
  OWL FLEXDUCT
  RETURN AIR REGISTERS & DUCTS
  SOUNDPROOFING for DUCTWORK
  SUPPLY DUCTS & REGISTERS
  TRANSITE PIPE AIR DUCTS
  UNDERSIZED RETURN DUCTS
  UNSAFE DUCT OPENINGS
  VIBRATION DAMPENERS
  WATER & ICE IN DUCT WORK
  WET CORRODED DUCT WORK
  ZONE DAMPER CONTROLS

ENERGY SAVINGS in buildings
EVAPORATOR COIL or COOLING COIL
EVAPORATIVE COOLING SYSTEMS
EVAPORATOR COIL or COOLING COIL
EXPANSION VALVES, REFRIGERANT

FAN, AIR HANDLER BLOWER UNIT
FAN AUTO ON Thermostat Switch
A/C REFRIGERANTS
A/C - HEAT PUMP CRITICAL DEFECTS
A/C DIAGNOSTIC FAQs
INSPECTION CHECKLIST - OUTDOOR UNIT
INSPECTION LIMITATIONS

FURNACES WARM AIR HEATING SYSTEMS
INDOOR AIR QUALITY IMPROVEMENT GUIDE

  • Thanks to Mark Cramer, Tampa Florida, for assistance in technical review of the "Critical Defects" section and for the photograph of the deteriorating gray Owens Corning flex duct in a hot attic. Mr. Cramer is a Florida home inspector and home inspection educator.
  • Thanks to Jon Bolton, an ASHI, FABI, and otherwise certified Florida home inspector who provided photos of failing Goodman gray flex duct in a hot attic.
  • Air Diffusion Council, 1901 N. Roselle Road, Suite 800, Schaumburg, Illinois 60195, Tel: (847) 706-6750, Fax: (847) 706-6751 - info@flexibleduct.org - www.flexibleduct.org/ -
    "The ADC has produced the 4th Edition of the Flexible Duct Performance & Installation Standards (a 28-page manual) for use and reference by designers, architects, engineers, contractors, installers and users for evaluating, selecting, specifying and properly installing flexible duct in heating and air conditioning systems.
    Features covered in depth include: descriptions of typical styles, characteristics and requirements, testing, listing, reporting, certifying, packaging and product marking.
    Guidelines for proper installation are treated and illustrated in depth, featuring connections, splices and proper support methods for flexible duct. A single and uniform method of making end connections and splices is graphically presented for both non-metallic and metallic with plain ends."
    The printed manual is available in English only. Downloadable PDF is available in English and Spanish. 
  • Owens Corning Duct Solutions - www.owenscorning.com/ductsolutions/ - provides current HVAC ductwork and duct insulating product descriptions and a dealer locator. Owens Corning Insulating Systems, LLC, One Owens Corning Parkway, Toledo, OH 43659 1-800-GET-PINK™
  • "Flexible Duct Media Fiberglas™ Insulation, Product Data Sheet", Owens Corning - see owenscorning.com/quietzone/pdfs/QZFlexible_DataSheet.pdf
    "Owens Corning Flexible Duct Media Insulation is a lightweight, flexible, resilient thermal and acoustical insulation made of inorganic glass fibers bonded with a thermosetting resin."

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

  • Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
  • Complete List of Air Conditioning & Heat Pump Design, Inspection, Repair Books at the InspectAPedia Bookstore.
  • Home Reference Book - Carson Dunlop The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 2010, $69.00 U.S., is available from Carson Dunlop. The Home Reference Book is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. InspectAPedia.com ® author/editor Daniel Friedman is a contributing author. Field inspection worksheets are included at the back of the volume.
  • Modern Refrigeration and Air Conditioning, A. D. Althouse, C.H. Turnquist, A. Bracciano, Goodheart-Willcox Co., 1982
  • Principles of Refrigeration, R. Warren Marsh, C. Thomas Olivo, Delmar Publishers, 1979
  • "Air Conditioning & Refrigeration I & II", BOCES Education, Warren Hilliard (instructor), Poughkeepsie, New York, May - July 1982, [classroom notes from air conditioning and refrigeration maintenance and repair course attended by the website author]
  • Refrigeration and Air Conditioning Technology, 5th Ed., William C. Whitman, William M. Johnson, John Tomczyk, Cengage Learning, 2005, ISBN 1401837654, 9781401837655 1324 pages
  • Carson Dunlop, Associates, Toronto, have provided us with (and we recommend) Carson Dunlop Weldon & Associates' Technical Reference Guide to manufacturer's model and serial number information for heating and cooling equipment ($69.00 U.S.).
  • Air Conditioning Inspection, Diagnosis, Repair, Efficiency all the basics for home owners, inspectors, new repairmen
  • NewAir Conditioning SEER - New DOE Air Conditioner and Heat Pump Efficiency Standard
  • Asbestos HVAC Ducts and Flues field identification photos and guide
  • Fiberglass: Indoor Air Quality Investigations: Fiberglass in Indoor Air, HVAC ducts, and Building Insulation
  • ...
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