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HVAC School - For Techs, By Techs

Aug 10, 2023

Joey Henderson joins the podcast to talk about airflow and how we can get air where it needs to go.

Duct design is one of the subjects that fuel Joey's passion for HVAC. In many cases, people focus too heavily on the equipment when diagnosing airflow problems; sometimes, the equipment simply can't perform as it should due to a poorly designed duct system. In residential HVAC, many duct systems aren't adequately planned out, and the airflow can't overcome restrictions like filters. We also need to keep in mind that flex ducts need to be as straight and tight as possible, and it's usually best if we slightly upsize them (compared to sheet metal).

Even though balancing dampers aim to solve airflow problems, they often lead to other issues when installed and used incorrectly. In many cases, proper duct design would solve problems without the need for balancing dampers. Bypass dampers are also commonly misapplied.

Some technicians also aren't properly trained to position their static pressure probes appropriately to measure total external static pressure, which leads to faulty readings and misinformed diagnoses. We can start by looking at things that can improve system performance at the equipment, like filtration; we can think of the equipment as the heart and the duct system as arteries (with static pressure as blood pressure), and the equipment also has the biggest pressure drop.

Joey and Bryan also discuss:

  • Joey's HVAC beginnings in the Navy and current work in education
  • Educators' unique communication styles
  • Learning from other educators as an educator
  • Plenum boxes and turbulence
  • Using wye fittings
  • Laminar flow
  • Modifying existing duct systems
  • Motors and amp draw
  • Building duct transitions
  • Clients and money limitations
  • Communicating with customers about airflow issues
  • Ethics around duct design
  • Unique duct challenges with inverter-driven systems


Check out Joey's training, social media, and contact information at

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