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Ductwork Performance Testing

A/C Running Non-Stop When It’s Quite Hot? (Part 3 of 4)

what is duct work and what can go wrong

Is Your Ductwork Performance What It Should Be?

Ductwork Performance is reduced (sometimes dramatically) if ductwork is installed incorrectly.  Ductwork Performance can also be reduced due to problems which have developed over the years. Reduced air flow causes the HVAC to run longer, decreasing HVAC System efficiency, shorting HVAC System lifespan, and increasing operating costs.  If your HVAC System fails the Ductwork Performance test (with clean filter and cooling-coil) you need corrective work performed on your ductwork.

An HVAC Airflow Pressure-Test Will Tell About Ductwork Performance:

  • If cooled / heated air is escaping into the attic.
  • If air-flow is restricted somewhere.

Ductwork Problems Which Cause Ductwork To Fail The Pressure Test

gaps in ductwork Ductwork could be leaking cooled & heated air into the attic.


Ductwork could need its connections resealed.

ductwork sealed with duct tape ductwork sealed with mastic ductwork sealed with mastic

Duct tape fails very quickly, causing leaks.               Mastic to seal Ductwork                          Ductwork sealed with mastic

This YouTube Video Shows Sealing Ductwork With Mastic:  YouTube Video — Sealing Ductwork With Mastic


poorly installed flexible ductwork Flexible Ductwork can be kinked or compressed.


What Flexible Ductwork Looks Like When It Was Correctly Installed — And When It Was Not…

correctly installed flexible ductwork

Correctly Installed Flexible Ductwork

Here is how you can tell:

  • The ductwork has supports close enough together that it does not sag much between the supports
  • The bends are not sharp.  Sharp bends kick flexible ductwork over time.  When a kink is present air-flow is dramatically reduced.
  • There are no areas where the ductwork is compressed, typically to make it fit in a location where it does not belong.

Incorrectly Installed Flexible Ductwork:

hanger compressing ductwork poorly installed flexible ductwork poorly installed flexible ductwork poorly installed flexible ductwork

These photos show damaged flexible ductwork.  This could have happened during or after it was installed:

flex-duct-crushed-no-air-flow ductwork -- damaged 1

Photo-Diagram Showing All Components Within Flexible Ductwork.    

photo of flexible ductwork with all components identified




This article gives insight into why a/c runs all the time during quite hot weather.  Discussed here are ductwork issues which cause an a/c (which is working properly) to run non-stop when it’s quite hot outside.

Al’s Plumbing, Heating and A/C performs ductwork pressure-testing and provides ductwork repairs or modifications if needed.  This ensures you are not wasting money with an HVAC system running longer than it would be if operating correctly and at its peak efficiency.

Al’s also provides Maintenance, Repair, and Replacement services for HVAC Systems.  Al’s can ensure your HVAC is operating at its peak capacity and efficiency.  This will minimize energy costs and increase your home’s comfort-level year round.

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