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Tech Tips:

The “Approach” Method of Charging and Condenser Efficiency

We have discussed many methods for checking a refrigerant charge without connecting gauges over the last few years. Recently, I've been thinking about the “approach” method of charging that many Lennox systems require. What is the Approach Method? The “approach” simply refers to the temperature difference between the liquid line leaving the condenser and the […]

Is it too cold to set the charge?

I've heard the phrase, “It's too cold to set the charge!” for as long as I've been in the trade. I've also heard some variations of, “We need to come back and set the charge,” or, “We need to come back to do XYZ [some other thing].” Granted, there are cases where you do actually […]

Charging Systems with Accumulators

In air conditioning service, we don't always see systems with accumulators. In fact, they are pretty uncommon unless you work on a lot of heat pumps. However, as heat pumps gain popularity, charging systems with accumulators will be a good skill to have in your tool bag. We are Carrier dealers in Florida, so we […]

Flash Gas

When we say that there is “flash gas” at a particular point in the system, it can either be a bad thing or a good thing, depending on where it is occurring. Flash gas is just another term for boiling. It is perfectly normal (and required) that refrigerant “flashes” or begins boiling directly after the […]

Is It OK To Top Off With R410a?

I am consistently surprised by how much false information still circulates out in the field, and one of the ones I hear often is the idea that you cannot or should not “top-off” or recharge R410a systems on top of an existing charge of R410a when the system is low. So, to be clear, before […]

Checking the Charge on a Heat Pump in the Winter

When you ask many people nowadays how to check the charge on a heat pump during low outdoor temps, they will say that you need to “weigh in and weigh out” the charge. While this may be an effective method, it isn't always practical. Now, if you are making a refrigerant circuit repair, weighing out […]

Know the Limits of Subcooling

This article was written by RSES CM and excellent market refrigeration tech Jeremy Smith. Thanks, Jeremy! I frequently see techs online struggling with charging or troubleshooting refrigeration equipment and using subcooling as a diagnostic or charging method. Please don't do this unless you understand it fully. Many times, trying to charge a refrigeration system to […]

The “5 Pillars” of Residential A/C Refrigerant Circuit Diagnosis

Suction pressure, head pressure, subcooling, superheat, delta T. Taking all five of these calculations into account on every service call is critical. Even if you must do further diagnostic tests to pinpoint the problem, these five factors are the groundwork before more effective diagnostics can be done. I would also add static pressure as an […]

Testing, Recovery, and Charging a Sealed System

There are many appliances with compression refrigeration circuits that do not have ports installed for testing, recovery, charging, and evacuation. These can include window units, PTACs, fountains, refrigerators, and much more. This fact presents a challenge any time you suspect or know there is a refrigerant circuit issue. How can you diagnose and repair when […]

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HVAC School – For Techs, By Techs

Real training for HVAC ( Heating, Ventilation, Air Conditioning and Refrigeration) Technicians. Including recorded tech training, interviews, diagnostics and general conversations about the trade.

In this episode from the 6th Annual HVACR Training Symposium, Brynn Cooksey, a home performance contractor from Michigan and technical training business owner, reveals how indoor air quality (IAQ) testing transformed his contracting business from a commodity service into a profitable specialty. Cooksey shares his proven methodology for turning IAQ into an “instant profit center” by implementing systematic testing on every service call.

Cooksey opens with a striking reality check: according to the EPA, Americans spend 90% of their time indoors, yet indoor air quality is 2-5 times worse than outdoor air. This presents a massive opportunity for HVAC contractors, as he explains that consumers are already spending $10 billion annually on air quality products at big box stores – but they’re treating symptoms rather than addressing root causes. His approach involves educating contractors on how to position themselves as the solution providers rather than letting customers self-diagnose with retail products.

The presentation dives deep into six critical IAQ parameters that every contractor should measure: particles (especially dangerous PM 2.5), volatile organic compounds (VOCs), carbon dioxide, carbon monoxide, humidity, and temperature. Cooksey emphasizes his “test in, implement solution, test out” methodology, demonstrating how this systematic approach not only ensures customer satisfaction but also provides concrete proof of value delivered. He shares real-world examples, including a dramatic case where routine IAQ testing during a water heater service call revealed a cracked heat exchanger that could have been life-threatening.

The episode concludes with extensive coverage of ventilation strategies, which Cooksey calls the “silver bullet” for IAQ improvement. He walks through the differences between supply-only, exhaust-only, and balanced ventilation systems, strongly advocating for Energy Recovery Ventilators (ERVs) as the optimal solution. His practical approach includes using DOE’s free REDCalc tool for proper ventilation sizing and emphasizes the importance of controlled ventilation over relying on natural air leakage – debunking the myth that “houses need to breathe.”

Topics Covered

The IAQ Business Case: How testing indoor air quality on every service call creates new revenue streams and differentiates contractors in a commoditized market
Six Critical IAQ Parameters: Detailed explanation of particles (PM 2.5), VOCs, carbon dioxide, carbon monoxide, humidity, and temperature – what they are, how to measure them, and health impacts
Systematic Testing Methodology: The “test in, implement solution, test out” approach that provides measurable results and customer proof of value
Particle Control Strategies: Source control, enhanced filtration (MERV 13-16), duct cleaning benefits, and duct sealing with Aeroseal technology
Chemical and VOC Management: Understanding formaldehyde and benzene sources, proper storage techniques, and why PCO devices aren’t recommended
Carbon Monoxide Detection: The life-saving importance of testing every home, understanding chronic vs. acute exposure, and why standard CO detectors aren’t sufficient
Ventilation as the Silver Bullet: Comprehensive coverage of supply-only, exhaust-only, and balanced ventilation strategies, with strong emphasis on ERV systems
Practical Implementation Tools: Using DOE’s REDCalc tool for ventilation sizing, integrating IAQ testing into service calls, and customer communication strategies
Real-World Case Studies: Multiple examples of IAQ testing uncovering dangerous conditions, from cracked heat exchangers to improper combustion appliance installation
Building Science Integration: How IAQ testing leads to broader building performance improvements, including duct sealing, insulation, and equipment sizing corrections

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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IAQ for the HVAC Technician w/ Brynn Cooksey

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