In this episode, Bryan welcomes back Louise Kellar of UEi Test Instruments for a deep dive into getting more out of a digital clamp meter than the basic volts, amps, and ohms most techs rely on every day. The tool in the spotlight is UEi's High Accuracy Clamp Meter (HAC), which is accurate when dealing with the low current draws common on modern condenser fan and blower motors and is critical for reliable wattage and capacitor-under-load testing.

The podcast also walks through a series of lesser-used but valuable meter functions, including microamp measurement for flame rectification testing, diode testing for diagnosing boards on mini-splits, the Low Z setting for eliminating ghost voltage readings and safely bleeding capacitors, and the safety-locking temperature toggle that prevents technicians from accidentally crossing voltage and thermocouple leads.

Bryan and Louise also cover common mistakes, such as not knowing when to use continuity or resistance and auto-ranging mistakes, as well as some crucial takeaways about true RMS measurements, temperature settings, and CAT safety ratings.

This episode contains embedded sponsor messages from Refrigeration Technologies, Carrier, NAVAC, and Filtrete.

Resources

• UEi products, manuals, and resources
• HVAC Multimeter Skills: Continuity vs. Resistance & Diode Testing (video)
• CAT Ratings on Electrical Multimeters (tech tip)
• HVAC School calculators
• Submit a podcast question
• Learn about the GRIT Foundation

Purchase your tickets or learn more about the 8th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

In this short podcast, Bryan and Roman discuss premature coil failure in ductless mini-splits and VRF equipment.

These coils are susceptible to a few different types of corrosion. Warmer coil saturation temperatures and shorter runtimes result in lower latent capacity; whatever moisture is on the coil dries on the coil instead of draining out. Minerals and chemicals (including chlorides from bleach or cleaners) interact with the coil and may cause corrosion, including formicary ("ant's nest") corrosion. Leaks and corrosion may be environmental rather than entirely attributable to manufacturer defects.

Technicians can use proper cleaners with correct dilution ratios and rinse the coils. In situations where the environment contributes to coil corrosion, such as with substances off-gassing or dealing with coastal air, we will need to dilute the pollutants by ensuring proper ventilation. Dilution needs to be intentional, especially in hot-humid climates, and ventilating dehumidifiers with good filtration may be a good move. Source control and filtration are also good mitigation strategies, and clear, open client communication can help clients understand the problem and make informed decisions about their HVAC system.

This episode contains embedded sponsor messages from Refrigeration Technologies, Carrier, NAVAC, and Fieldpiece.

Resources

• Coil Corrosion w/ Kevin Hart and Bryan Orr
• Living in a World of Acids (and why HVAC coils are secretly crying for help)
• HVAC School calculators
• Submit a podcast question
• Learn about the GRIT Foundation

Purchase your tickets or learn more about the 8th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

In this live episode, Bryan sits down with Jim Bergmann of measureQuick and NAVAC trainers Zane and Jesse Stewart for a deep, technician-focused conversation about advanced refrigerant recovery. The group covers diverse system types and environments, including low-ambient recovery.

Recovery machines cannot pump straight liquid, which we need to be mindful of during service. That said, vapor-only recovery works fine for small charges, but push-pull recovery becomes worthwhile once a system holds more than roughly ten pounds of refrigerant. Refrigerant and tank contamination, as well as general safety (including tank fill limitations), are a couple of other field challenges worth considering in our recovery best practices.

Some best practices to take away from this episode include attaching to the vapor side of the tank (and inverting it), pulling Schrader cores, using large hoses instead of manifold gauges, and keeping the recovery tank cool to eliminate restrictions.

This episode contains embedded sponsor messages from Refrigeration Technologies, Carrier, Copeland, Santa Fe Dehumidifiers, and TruTech Tools.

Resources:

• Don't Overfill Recovery Tank Cylinders the Easy Way
• Recovery Tank Safety
• Recovery Tank Capacity
• Push-Pull Recovery
• Recovery Best Practices w/ NAVAC
• HVAC School calculators
• Submit a podcast question
• Learn about the GRIT Foundation

Purchase your tickets or learn more about the 8th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

In this short podcast episode, Bryan and Roman talk about the A2L & refrigerant transition again, particularly sensors on R-454B and R-32 equipment.

Since the beginning of the A2L transition, we have seen the equipment evolve and begin requiring accessories, including refrigerant sensors and blower recirculation systems (BRS) or dissipation boards. In a BRS, the blower turns on and dilutes the refrigerant in the space to keep the refrigerant concentration below the lower flammability limit (LFL) and prevent ignition. Some systems may also have isolation valves and pump themselves down whenever the A2L sensor trips. These sensors use MOS technology, which measures gas changes by tracking electrical connectivity shifts; they have limited lifespans and can become corrupted over time.

In the field, you may notice a running fan without the outdoor unit running. Some diagnostic boards might give you error codes, but if you don't and don't have 24V when you troubleshoot the issue, you may want to check the sensor. The sensors could be wet, tripped by VOCs, or even have been cut out.

This episode contains embedded sponsor messages from Refrigeration Technologies, Carrier, TruTech Tools, Fieldpiece, and Filtrete.

Resources

• A2L Dissipation Boards and Leak Sensors
• HVAC School calculators
• Submit a podcast question
• Learn about the GRIT Foundation

Purchase your tickets or learn more about the 8th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

In this episode, Bryan sits down with Mike Pastorello, owner of Refrigeration Technologies, and Ashley Lynds, director of education and brand management for Viper, to talk about the company's roots, its newest product launches, and where the brand is headed next. This podcast focuses on "The Lab" and how it integrates field technicians with product development.

Refrigeration Technologies was built on a "for techs by techs" philosophy after John, an HVAC technician with a chemistry background, began inventing products to solve his own field problems. Now, technicians are using their field problems to inspire innovation in the Refrigeration Technologies lab, and the Easy Dose is the first product that was developed, tested, and distributed via the "Lab" initiative.

The team also discusses chemical safety in their approach to products and what's really inside products like the Viper Pan & Drain Treatment and Nylog.

This episode contains embedded sponsor messages from Refrigeration Technologies, Carrier, NAVAC, Fieldpiece, and AHR Expo 2027.

Resources:

• Refrigeration Technologies
• AHR Expo
• Careful With Cleaners
• HeatShield Demo
• HVAC School calculators
• Submit a podcast question
• Learn about the GRIT Foundation

Purchase your tickets or learn more about the 8th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

In this short podcast episode, Bryan and Roman talk about the ethics of IAQ, particularly in terms of microbial growth testing vs. remediation conflicts, based on Roman's recent experience hiring a mold assessor and then a remediation expert in his home. Remediation is governed by S520 of the IICRC.

Microbial growth is tricky because it is often hidden and has real health effects, but there is a history of fraud in its assessment and remediation. To help combat that fraud, in Florida, assessment and remediation are two separate practices with two separate licenses. Roman got to see the differences in action by working with different assessment and remediation professionals and witnessing how the two practices depend on each other but differ.

First, an assessor came to Roman's house with testing equipment and a means of collecting lab samples; this assessment started outdoors and continued indoors, and the assessor produced a thorough 87-page report with the tool findings, lab findings, and pictures. As with HVAC, the results are based on science and data, and reputable assessors are licensed, independent, and have the tools and training to carry out the job without using scare tactics on homeowners.

After the assessment, remediation must be done separately. In Roman's home, all equipment was isolated, and the house was brought under negative pressure with HEPA filtration. There was also surface cleaning and HEPA vacuuming. Then, after remediation, there is a post-remediation verification (PRV). The PRV is carried out by a mold assessor, not a remediator, and determines whether the remediator did their job (and in some states, like Florida, there are criminal penalties for referral payments between assessors and remediators). A PRV consists of IAQ tests and lab measurements, and the results should reveal lower numbers than the original assessment and the outdoor air.

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

Purchase your tickets or learn more about the 8th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

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.

400 CFM per ton is useful—until it isn't.

In this episode, Bryan and Ty take on one of the trade's favorite rules of thumb. It can be a reasonable starting point for many systems under moderate, near-sea-level conditions, but it is not a universal target. Proper airflow depends on actual delivered capacity, sensible and latent load, air density, climate, manufacturer data, and what the system is supposed to accomplish—not just the tonnage stamped on the cabinet.

They explain why dry-climate and high-altitude applications may require more volume airflow, why humid applications often use less coil airflow to improve moisture removal, and why mass flow matters more than volume alone. They also cover nominal versus actual capacity, suction-line pressure drop, equipment-specific performance at 208 V, Manual S and expanded performance data, and field verification with measureQuick and the TrueFlow® Grid.

The takeaway is simple: use the rule as scaffolding, then measure the system and follow the equipment data.

This episode contains embedded sponsor messages from Refrigeration Technologies, Carrier, NAVAC, and Filtrete.

Resources:

• Not All CFM Are Created Equal
• Impacts of Decreasing Evaporator Airflow
• Troubleshooting With DTD
• AHRI Data vs. Manufacturer Expanded Performance Data
• Bypass Dehumidification Airflow Design
• HVAC School calculators
• Submit a podcast question
• Learn about the GRIT Foundation

Purchase your tickets or learn more about the 8th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

In this short podcast episode, Bryan and Roman Baugh talk about indoor air quality and microbial control, specifically MERV 15 filter physics and how it all works when bringing in outdoor air.

We filter indoor air to keep dust and particles off the equipment and keep them from circulating through the air. However, we also need to filter fresh air. While indoor air has several pollutants, including dust and VOCs, that make outdoor air dilution a sensible solution, outdoor air also has spores and other pollutants we want to filter out, and its quality can be hard to evaluate. Roman had an ERV that fed his VRF system, and it had significant microbial growth inside; he had some MERV 6 filtration on it, but that didn't capture particles effectively enough. MERV ratings measure the ability to filter particles out, and we use a unit called microns to measure particle size; higher ratings indicate a greater filter surface area and a better ability to filter out smaller particles.

ASHRAE 52.2 divides particles into three categories: E1 (ultra-fine particles between 0.3 and 1 micron in diameter), E2 (fine particles between 1 and 3 microns), and E3 (coarse particles between 3 and 10 microns in diameter). MERV 15 filters have a 90% capture rate of E2 particles and a 90%+ capture rate of E3 particles. Fungal spores tend to fall in the E2 or E3 category, and filtration can keep those from coming into the home with fresh air; bringing in fresh air to dilute indoor pollutants is good, but we need a nuanced approach, and good filtration (without bypass) is part of that equation. Filters can also capture much smaller particles due to the way those particles move. Smaller particles move via Brownian motion, which makes them move erratically and more likely to collide with filter media.

However, filter use and design, as well as fresh air intake location, can also affect filter efficacy. Filters that don't fit well in the slot enable bypass, and some filters might be restrictive. Exhaust ventilation outlets also play a role, as wind can bring those pollutants back to fresh air intakes.

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

Purchase your tickets or learn more about the 8th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

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.

In this episode, Bryan Orr sits down with Ty Branaman for a wide-ranging conversation about what it really takes to be a good on-call technician. They open by reminiscing about how dispatch technology has evolved over their careers — from pagers, radio codes, and outdated paper map books to MapQuest, early GPS units, and today's 24-hour dispatch systems. That trip down memory lane sets up the episode's central theme: while the tools have changed, the mindset needed to succeed on call has not. Both hosts agree that being on call can be genuinely enjoyable when a technician learns to embrace the autonomy, the bigger paychecks, and the quieter, less stressful roads that come with nights and weekends.

A major thread running through the discussion is self-discipline and long-term thinking. Bryan and Ty encourage younger techs to treat on-call money as an opportunity rather than spending cash — saving and investing overtime pay instead of financing trucks, boats, or other lifestyle upgrades. They share stories about the financial traps of seasonal trade work, the value of staying in a consistent routine even at 2 a.m., and how cutting corners under fatigue is often what leads to injuries or callbacks. Ty compares a disciplined on-call tech to a pilot running through a pre-flight checklist: the process matters just as much in the middle of the night as it does at noon.

The conversation also digs into customer relationships and judgment calls in the field. They talk candidly about the difference between genuine emergencies and entitled or overblown complaints, and how companies that over-market "24/7 service" can create unrealistic customer expectations. Bryan shares a story about temporarily misting a struggling condenser to get an elderly client through a brutal heat wave, using it to illustrate the kind of judgment-based, get-them-by fix that defines old-school on-call work — as opposed to always pushing for a full sale. Safety boundaries, cutting corners responsibly, and the excitement of solving unpredictable problems on the fly are all discussed as part of what makes the work rewarding despite its challenges.

Finally, Bryan and Ty turn to advice for company owners and service managers. They emphasize building fair, well-communicated on-call rotations, respecting technicians' personal time, and charging appropriately for after-hours work so that both customers and technicians value it. Ty argues that the industry needs to reframe HVAC work as a skilled trade rather than commodity labor, and that companies should be careful not to chase more emergency calls than their technician pool can sustainably handle. The episode closes with reflections on career growth, mentorship, and the kindness that comes from helping teammates cover on-call shifts for one another.

Topics Covered

• The evolution of dispatch: pagers, radio 10-codes, paper map books, and early GPS
• Why on-call work can be enjoyable: autonomy, higher pay, and quieter roads
• The hardest part of on-call: getting called back out after coming home
• Customer expectations, entitlement, and the impact of "24/7 service" marketing
• Saving and investing on-call earnings instead of overspending on trucks and boats
• Staying in routine and following checklists even late at night to avoid callbacks
• Sleep, hydration, and avoiding excess caffeine while working on-call shifts
• Judgment calls and temporary fixes to get customers through emergencies safely
• Knowing your personal safety and ethical limits when cutting corners
• Career paths with less on-call demand: maintenance roles, installation, stationary engineering
• Reframing HVAC service as a skilled trade rather than commodity labor
• Building fair, well-communicated on-call rotations to prevent technician burnout
• Mentorship, teamwork, and covering shifts for coworkers with families

Subscribe to Ty's YouTube channel, @love2hvac.

Learn more about the work we're doing with Ty at the GRIT Foundation at https://www.thegritfoundation.com/.

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

Purchase your tickets or learn more about the 8th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

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.

In this short podcast episode, Bryan and Roman talk about Florida law and how it relates to the "M-word" (mold) and the legal boundaries our techs must respect when they communicate with customers. HVAC School and Kalos are NOT mold experts, but we have experience as HVAC professionals who encounter suspicious microbial growth in our market (and cannot diagnose or remediate mold).

We cannot use the word "mold" because "mold" MUST be diagnosed by a certified mold assessor via laboratory testing according to Florida law. A guess based on sight does NOT qualify as a diagnosis; it is the equivalent of diagnosing a compressor failure as acid contamination without a test that proves the presence of acid. Residential property owners, however, are allowed to identify, remediate, and speak freely about mold in their own homes (which Roman can do because he hired mold assessors and remediators in his home).

Florida limits HVAC contractors from diagnosing mold (or removing more than 10 contiguous square feet while removing, maintaining, or installing equipment) to prevent scare tactics in sales, such as by diagnosing "toxic mold" in a drain, or to sweep larger problems under the rug. There are also many different mold types that have specific characteristics that can only be identified by an assessor; HVAC contractors are not trained to recognize those. However, mold is part of our work whenever we clean coils, HVAC units distribute air (which contains mold spores from outside), and we manage moisture (which contributes to fungal growth).

Mold assessors also have specific diagnostic tools and send lab samples. HVAC contractors don't have those resources, training, or certification. As HVAC contractors, need to be educated on mold, but we also need to understand our limitations; we can't diagnose it or make decisions for customers.

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

Purchase your tickets or learn more about the 8th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

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.