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HVAC School - For Techs, By Techs

Nov 23, 2023

Bryan Orr hosted a live podcast discussion all about 90% efficient furnaces with HVAC professionals Ty Branaman, Adam Mufich, and Matthew Bruner. They covered the basics of how 90% furnaces work compared to traditional 80% furnaces, troubleshooting tips, and best practices for installation and service.

A key difference with 90% furnaces is the addition of a secondary heat exchanger that extracts more heat from the exhaust gases before they go out the flue. This allows the furnace to achieve at least 90% efficiency. The condensing of water vapor in the exhaust also releases latent heat. However, the acidic condensate must be properly drained, and pipes must be corrosion-resistant. Proper airflow is also critical.

The experts emphasized starting any service job by carefully looking over the furnace and venting. Check for any signs of problems like leaks, debris buildup, or animals/pests blocking vents. Verify gas supply and use combustion analysis to optimize performance. When troubleshooting, methodically trace through the sequence of operations. Pressure switches, flame sensors, and airflow issues are common culprits.

The podcast concludes with a reminder that extensive training content on HVAC topics like this is available through HVAC School and other industry experts. Continuing education and an open, collaborative mindset are important for professional growth.

Key topics covered:

  • How 90% furnaces achieve higher efficiency with a secondary heat exchanger
  • Water condensation and corrosion concerns - importance of drainage and pipe material
  • Verifying gas supply, venting, airflow, and using combustion analysis
  • Troubleshooting tips - visually inspecting, tracing sequence of operations, checking pressure switches and flame sensor
  • Proper installation positioning and intake/exhaust vent sizing per manufacturer specifications


View the entire livestream with Ty on our YouTube channel HERE.

Learn more about the 5th Annual HVACR Training Symposium at

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