HVAC School - For Techs, By Techs

• Delta T Talk w/ JD Kelly

  Bryan from HVAC School interviews JD Kelly, known as "student of HVAC" on Instagram, about Delta T measurements in HVAC systems. This episode dives into the fundamentals of Delta T, common misconceptions, and proper measurement techniques. JD explains that Delta T is simply a temperature difference between two points of the same medium, which is often misunderstood in the industry. Many technicians are taught to measure between return grills and supply registers, but this approach can lead to inaccurate readings due to external factors like duct leakage or heat gain from attics. The proper measurement should be taken directly at the equipment to evaluate how the evaporator coil is performing. Humidity plays a significant role in Delta T measurements, which JD discovered when researching the fundamentals. Bryan elaborates on this point, explaining that in high-humidity environments (like Florida), more energy goes toward removing moisture (latent heat) rather than cooling the air (sensible heat), resulting in lower Delta T readings. This is why a newly repaired unit in a humid house might initially show lower readings but improve as the home dries out. The discussion highlights why the common "20-degree Delta T" rule of thumb isn't universally applicable and requires context. Key Topics Covered: Definition of Delta T: Temperature difference between two points of the same medium Difference between Delta T and TD (temperature difference) Proper probe placement for accurate Delta T readings Impact of humidity on Delta T measurements How regional differences affect expected Delta T values Relationship between CFM (airflow) per ton and Delta T readings Common mistakes: Adjusting equipment based solely on Delta T readings Challenges of applying Delta T in heat pump heating mode How temperature dead spots can affect readings Why Delta T readings must be considered alongside other diagnostic tests The danger of making unnecessary adjustments to HVAC systems Why high Delta T isn't always good and low Delta T isn't always bad   JD's Delta T tech tip: https://hvacrschool.com/solving-delta-t/  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 6th 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

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• Fire Sprinklers - Short #239

  In this short podcast episode, Bryan talks about fire sprinklers and how to avoid setting them off on job sites. Fire sprinklers have an element in the center that expands when exposed to heat (like a TXV sensing bulb) and breaks the glass. When the glass breaks, the fire sprinkler starts pouring out water. In some cases, fire sprinklers are linked to a larger fire suppression system in which several may go off at once, but most of the time, only a single fire sprinkler will go off if bumped or exposed to heat. If you're using torches or doing any form of hot work in a closet or other location with a fire sprinkler, make sure to keep torches away from the heat-sensitive bulb or at least cover the sprinkler with a wet rag (and follow your company's guidelines). Blunt force is another possible issue, so we want to avoid hitting the sprinklers with lifts, ladders, or building materials like studs. Keep clearances in mind, and watch out for your colleagues. You can get some specialty-built cages to protect the sprinklers, but awareness is one of the best ways to protect fire sprinklers. If possible, make sure signage is posted or that you alert other people in the area about the fire sprinklers. If the fire sprinkler does go off, make sure you can quickly reach the person(s) who can access the fire shutoff or direct you to the fire shutoff. While fire sprinklers won't pose much of a personal safety hazard, property damage is a major concern. Training and awareness are the keys to preventing property damage due to fire sprinklers.   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 6th 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

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• The PATH to High Performance HVAC w/ David Richardson

  In this engaging session, David Richardson breaks down the concept of high-performance HVAC, offering a clear roadmap for industry professionals looking to elevate their craft. Richardson argues that the HVAC industry has long been focused on equipment rather than complete systems, leading to widespread inefficiencies. The average system delivers only about 57% of its rated capacity into buildings, while even code-approved systems barely reach 63%. By implementing high-performance HVAC principles, contractors can achieve up to 88% efficiency while improving safety, health, comfort, and energy performance. Richardson presents a practical framework using the acronym "PATH" - Pressure, Airflow, Temperature, and Heat (BTUs) - as a step-by-step approach to implementing high-performance HVAC. He emphasizes starting with static pressure testing, which he calls "the foundation of airflow" and one of the most misunderstood principles in the industry. Just as doctors check blood pressure as a vital sign during every visit, Richardson advocates for measuring static pressure on every call, or at minimum, when encountering "red flag" issues like repeated equipment failures. From there, professionals can progress to measuring airflow, temperature, and finally BTU delivery to create complete system diagnostics. The presentation offers a journey-based approach, acknowledging that implementation takes time and requires breaking old habits. Richardson introduces the "one degree principle," suggesting that change happens incrementally, with small improvements eventually leading to breakthrough moments. He urges contractors to apply this methodology not just to equipment, but to extend testing into duct systems and even the building envelope. By making these changes visible through measurement, contractors can prove value to themselves, their teams, and ultimately their customers, transforming the way HVAC work is perceived and delivered. Key Topics Covered: The definition of high-performance HVAC: getting back to craftsmanship, challenging the status quo, and confirming work through measurement The industry problem: focusing on equipment instead of complete systems, resulting in just 57% of rated BTU capacity reaching conditioned spaces The PATH framework: Pressure, Airflow, Temperature, and Heat as building blocks for system diagnostics How to implement static pressure testing as the foundation for airflow diagnostics The importance of measuring at both equipment and register/grille locations Breaking down implementation into three areas: equipment, ducts, and building envelope STEPS approach: Show, Teach, Equip, Promote, with application to yourself, your team, and your customers The "one degree principle" for making incremental changes that lead to breakthrough results Common obstacles to implementation and how to overcome resistance to change How measurements make your work transparent and lead to better performance   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 6th 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

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• Estimating Tips and Software

  In this episode of the HVAC School Podcast, host Bryan sits down with Phil, the executive electrical team leader at Kalos who has transitioned into the world of estimating. Phil shares his extensive background in electrical work dating back to 1994, from his high school electrical elective to running his own business for eight years before joining Kalos and eventually establishing their estimation department. The conversation delves deep into the fundamentals of estimating in the trades, contrasting traditional qualitative approaches with more rigorous quantitative methods. Phil emphasizes that good estimating is about "finding the truth" - understanding the actual costs of materials and labor for a project. They discuss how traditional estimating often relies on heuristics and past experiences with similar jobs, while more detailed estimating involves comprehensive takeoffs and assembly-based counting. The pair explores how estimation isn't just about producing a final number but should provide valuable information that transfers to the production phase. A highlight of the episode is Phil's introduction of his self-developed estimating software called Unity Build. He explains how his interest in AI technologies led him to learn programming and eventually create this cloud-based solution that integrates AI assistance while maintaining the fundamental tools needed for thorough estimating. The software allows for collaboration between team members, is entirely browser-based, requiring no downloads, and is priced at $125 per month per seat. Bryan emphasizes that this is Phil's own business venture that he's taken an interest in, and they both stress that potential users should buy it for what it currently offers, not future promises, though they are committed to continuous improvement. Topics Covered: Phil's 30+ year journey in electrical work and how he learned estimating The difference between qualitative (heuristic-based) and quantitative (detailed takeoff) estimating approaches Unit pricing vs. assembly-based takeoffs in estimating How good estimating transfers value to the production phase The workflow of detailed estimating from information gathering to closeout Labor factoring and how it affects cost calculations Phil's development of Unity Build estimation software using AI integration Cloud-based advantages of the new software, including collaboration capabilities How Unity Build facilitates handoff from estimating to production Pricing model ($125/month per seat) and target customers (small to mid-sized contractors) The importance of estimating honesty and finding the "truth" in project costs   Check out Unity Build Estimation at https://unitybuildestimation.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 6th 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

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• Nylog, Oil? Where does it go? - Short #238

  In this short podcast, Bryan answers a listener-submitted question about Nylog, oil, and where you put them when you're making flares. Nylog is a thickened refrigerant oil (which is either POE for Nylog Blue or mineral oil for Nylog Red), and it's miscible with the refrigerant and moves with it through the circuit. You don't want to put excess Nylog on valves, but a small amount won't do harm. There are a lot of concerns about Nylog voiding the warranty, but it doesn't actually do that because it's nearly impossible to prove that Nylog caused the issue. Like oil, Nylog helps connections fit together (even threaded connections) and prevents galling. However, oil and Nylog also reduce friction, which will affect your torque specs when you use a torque wrench to tighten a connection. You don't need to tighten it as much, as you risk overtightening otherwise. When you apply Nylog, put a little bit on the front and back face of a flare (and the cone of the flaring block if you wish). You can put a small bead on the threads, but it's not an issue as long as you stay aware of your adjusted torque specs (low range). In our experience at Kalos Services, Nylog is particularly useful under vacuum and has helped us make high-quality flares that last a long time. Remember: Nylog is NOT leak lock, and it's not a traditional thread sealant.   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 6th 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

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