This episode featured Bryan Orr interviewing Sam Myers, the building science consultant at Retrotec. Retrotec manufactures products like blower doors and duct testers for measuring air tightness and leakage in buildings.

Sam discussed his role at Retrotec, which involves training contractors on using their tools properly, product design, software testing, presenting at conferences, and running trade show booths. He talked about the demanding travel schedule this requires but also the rewards of educating the industry.

The main topic was duct leakage testing - why it's important, how it's done, interpreting the results, and investigating and fixing duct leaks when problems are found. Sam explained that while a duct leakage test provides a number, that number alone doesn't indicate if the leakage is acceptable or problematic. However, it points technicians in the right direction for further investigating issues like comfort problems, indoor air quality concerns, or high energy bills.

He provided tips on using tools like smoke tests and thermal cameras to visually identify leaks, checking common leak areas like connections and return duct penetrations, and the value of testing before and after making repairs to verify the work. Sam also discussed using low-cost manometers for other tests, like checking room pressure imbalances caused by duct leaks.

Topics covered included:

• Sam's role and work at Retrotec
• The importance of duct leakage testing
• How duct leakage tests are performed
• Interpreting duct leakage test results
• Common duct leak sources like connections and return penetrations
• Methods for pinpointing and verifying duct leaks
• Using manometers for other diagnostic tests
• Tips for contractors getting started with duct testing

Learn more about Retrotec's resources at https://retrotec.com/.

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool.

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In this short Q&A podcast episode, Bryan answers Jeremy's question about checking the charge on rooftop units, and he gives some RTU tips.

Rooftop units often come in sets, so you can use a thermal camera to look at all of the RTUs and compare them. A thermal imaging camera may even show you where subcooling begins in the condenser, which can be a useful diagnostic hack. Try to avoid hooking up gauges each time you check the charge on a rooftop; RTUs have a fixed factory charge, and losses from your gauges can add up over time. Your senses will also come in handy; check for odd sights, sounds, and smells.

Checking suction pressure and superheat is less risky and imperfect, but it'll give you some diagnostic data. You can also check discharge temperatures to check for signs of compressor overheating (remember: 225 stay alive).

Here are some tips for RTUs:

• Get familiar with the service manual and wiring diagrams; these items will help you with the job and help you build on your knowledge of RTUs in general.
• Make sure you have all of your materials at the ready, including extra screws.
• Make sure you have access to the BAS system, if necessary.
• Safety is critical on rooftop units, especially when it comes to ladders, lockout/tagout, and ensuring that you have safe access to the unit (this burden is often on the client).
• Pay attention to specialized equipment, including ERVs and economizers.
• Be mindful of curb installation, transformer taps, and phase monitoring, as those items may not be set up properly.
• Build up a basic working knowledge of variable frequency drives or VFDs (or know where to find information about them; THIS livestream is a good start),
• Keep systems clean to prevent overheating.
• Prevent oil logging whenever you have to replace a compressor.

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool.

Purchase your virtual tickets for the 5th Annual HVACR Training Symposium at https://hvacrschool.com/Symposium24.

Subscribe to our podcast on your iPhone or Android.

Subscribe to our YouTube channel.

Check out our handy calculators here or on the HVAC School Mobile App for Apple and Android.