What are Flex Duct Installation Defects?

March 10, 2023

Flexible duct or Flex duct is often used in the installation of residential Heating Ventilation and Air Conditioning (HVAC) systems to distribute treated air throughout your house.  Flex duct, as opposed to rigid duct, was introduced into the residential construction market as a cost saving measure in central heating and air conditioning systems.  Flex duct is easier to install than rigid duct saving time and money during the construction process.  However, for efficient function of a flex duct system, proper installation practices must be installed to provide efficient fuction of the duct system.  Efficient installation of the duct system requires long, smooth runs of the duct, long sweeps or curves in the duct when needed, properly supported duct systems to minimize restrictions in the duct, and properly installed and functioning insulation on the duct to minimize heat (or cool) transfer.  Properly installed duct systems allow optimum air flow in the HVAC system and allows the HVAC to work as designed.  Regrettably, the duct system may be carelessly installed creating tremendous inefficiencies in the system.  

Let us look at some installation defects in flex ducts.   

 Bends and/or improper support in the intake line creating air flow restrictions. This condition restricts air flow reducing the efficiency of performance. 



A pinched or partially folded supply duct. This condition also drastically reduces air flow reducing the delivery of treated air to parts of your house – like bedrooms, the living room, kitchen, and dining room.



Long, unsupported duct.  These long, unsupported runs create inefficiencies by requiring longer duct runs, which reduce efficiency in the function of the system.  This condition also allows for more heat (or cooling) loss in the line. 


So, what do we do about these problems?  Most of the time, simply adjusting the ducts to create longer sweeps or bends and providing the correct supports to manage bending in the ducts is all that is needed.  Managing this problem is not hard, it simply takes patience and a little common sense.  A proficient homeowner or handyman is usually capable of managing this problem.  Commercially available straps are made to support the ducts and may be available for purchase at your local hardware store or lumber supply.  If some of the rooms in your house feel warmer or cooler than others, inspect the duct installation of your HVAC system for proper installation.  You may be surprised how helpful this repair could be in solving that problem!

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