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 Mobile ViewAIR 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 Leaky or Missing Air Ducts Hidden Missing Air Conditioner Duct Duct Retrofit Leaks Rooftop Duct Leaks RETURN DUCT AIR LEAKS SUPPLY DUCT AIR LEAKS 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 GAUGE, REFRIGERATION PRESSURE TEST REFRIGERANT CHARGING PROCEDURE REFRIGERANT DRIERS & FILTERS REFRIGERANT LEAK DETECTION REFRIGERANT LEAK REPAIR REFRIGERANT METERING DEVICES TEVs REFRIGERANT METERING CAPILLARY TUBES REFRIGERANT PIPING & DISTANCES REFRIGERANT PRESSURE READINGS 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 |
This article describes the effects of and how to find & repair blocked, clogged, crimped, loose or leaky air conditioning or heating ducts, leaky air duct connections, defective heating or cooling ductwork. The photo at page top shows what happens when cooling ducts are poorly connected through a crawl space. The crawl space was nice and cool but no cool air was being delivered to the living space. in addition, the air blowing around in the crawl space stirred up fiberglass and debris, including mold which increased the movement of these particles into the occupied space. For diagnosing poor air flow from an air conditioning or heating system also see RETURN AIR REGISTERS & DUCTS and SUPPLY DUCTS & REGISTERS. We also provide a checklist of more air duct troubleshooting suggestions at RETURN DUCT AIR LEAKS or at SUPPLY DUCT AIR LEAKS. And at UNSAFE DUCT OPENINGS we discuss certain air duct leaks and openings that are downright dangerous. © 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. This chapter continues discussion of common defects found in air conditioning duct work such as loose or leaky duct connections and their effect on the air conditioning or heating system. The master document, of which this is a chapter, describes the inspection of residential air conditioning systems (A/C systems) to inform home buyers, owners, and home inspectors of common cooling system defects.HVAC Duct Connection Leaks - Poor duct work connectionsMost-common Types of Air Duct Leaks
Disconnected Cool Air Supply Duct Hidden in Crawl AreaA client who lived in an apartment in New York City engaged our company to find why her city apartment could not get cool even though she had a new air conditioning system installed. We found that the ducts had become disconnected in the attic crawl space where the air handler was placed. It was wonderfully cool in the attic. The apartment was quite hot. So were the electric bills. Below at Soffit Cool Air Blast we describe a more egregious case of duct work that was missing entirely. These photographs show the two most-common air conditioning or heating duct leaks, at a loose falling metal duct connection (left photo) and at a poorly-secured flex-duct connection (right photo). Leaking supply air at these connections means less cool air (or warm if it's heat) delivered to the occupied space. If the air conditioning system output at the registers is poor, especially if it is working in some building areas but not others, one of the first things to check is the condition of the duct work. Look for and seal leaks like these. Also review the other duct and supply adequacy defects described at articles linked-to from the left of these pages.
In addition to making a mechanically sound connection beween duct sections (sheet metal screws, mechanical fasteners, nylon tie strips), we use metal foil tape to complete the seal on connected metal duct sections. The flex-duct connection was re-made and a tighter plastic band used to secure the flex duct in place. Watch out: don't rely just on duct tape to secure air ducts. But the cost of air duct leaks can be significant if the leak persists over a long time or in a location where blowing air or loss of dehumidification lead to mold or other indoor air quality concerns. Leaky air ducts can significantly increase building heating or cooling costs and can lead to other building or even health worries. The Florida air duct leak field report case just below illustrates this problem. Soffit Cool Air Blast Traced to Hidden Missing Air Conditioner Duct - Mistake by Builder
Cooling or Heating Duct Retrofit Leaks in Old buildings
These photographs show what can happen when existing registers and in-wall ducts are re-used when installing updated air conditioning or heating ducts in a building. The photo with my hand shows us feeling an up-draft from the basement below this first floor bath even though the air conditioning system was not running. The second photograph shows the problem as seen from the basement. The duct installer had simply pushed smaller-diameter new oval ducts up into the existing duct riser from the basement, leaving more than an inch of opening between the old rising duct and the new inserted duct. The result was leakage of cool air backwards into the basement when the central air conditioning system was running, and leakage of (moldy, smelly) basement air up into the living space through the same opening (by convection) when the air conditioning system was off. The cure for this duct leak was to use some spray foam insulation to make a better seal at the basement ceiling as well as around the register in upper floor. Rooftop Duct System Leaks & Water, Mold, and Pathogens
These photographs show what happens when a rooftop packaged-terminal air-conditioning airhandler Water ponded on the old, concave sections of air conditioning ducts on the roof of this commercial office space. As water leaked into the duct system it saturated fiberglass duct liner which in turn, had its normal coating of organic dust and debris from the building, risking an indoor mold or pathogen problem for some of the occupants. The cure for these duct leaks was costly: it was determined that it was less costly to completely replace the rooftop ducts with new metal ducts using outside insulation than it would have been to remove the contaminated fiberglass liner, clean the existing ducts, repair the leaks, and insulate their exterior. The work was combined with other building HVAC cleaning and repairs. More detailed suggestions of things to check in the duct system to improve airflow are at RETURN DUCT AIR LEAKS or at SUPPLY DUCT AIR LEAKS. Also see UNSAFE OPENINGS Questions & Answers regarding this article. Ask a Question or Search InspectAPediaHTML Comment Box is loading comments...
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