HVAC School - For Techs, By Techs Bryan Orr

In this short podcast episode, Bryan talks about motor protection types, including overloads.
The most common overload we see in residential HVAC is a built-in thermal overload, which is usually a bimetallic disk that flexes in response to heat (such as from a locked condition, electrical problem, or simply running hot) and opens the circuit. The two metals have different expansion and contraction rates, which causes the flexing; they will return to their original position once the motor cools down. In some cases, these can fail when they open and close too often; they are not designed for switching duty. Many circuit breakers have a similar thermal design and may be prone to nuisance tripping in the summer.
A lot of commercial motors rely on external overloads; some are even built into the electrical box rather than the compressor. These external magnetic overloads are often integrated into the contactor, which turns the motor on and off; this type of contactor is called a starter. These starters may have adjustable overload settings based on current, not just temperature (which may also respond to nuisance sources of heat and require a cooldown period). Some circuit breakers also trip magnetically and are less likely to be affected by temperature.
Thermistor-based overloads usually consist of a PTC (positive temperature coefficient) resistor; as temperature goes up, resistance goes up, which can take a motor winding out of the circuit. NTCs are in separate parallel circuits with relays; as the resistance decreases, it pulls in a coil that opens the circuit.
 
Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool. 
Learn more about the 5th Annual HVACR Training Symposium at https://hvacrschool.com/Symposium24.
If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.”
Subscribe to our YouTube channel at https://www.youtube.com/@HVACS. 
Check out our handy calculators HERE or on the HVAC School Mobile App (Google Play Store or App Store).

This podcast features a lively discussion on expansion valves, particularly thermostatic expansion valves (TXVs or TEVs), with a panel of expert guests - Corey Cruz (a market refrigeration tech), Matthew Taylor (head of refrigeration service at Kalos), and Joe Shearer (with Precision Air Conditioning).
The conversation kicks off by busting some common myths surrounding expansion valves. The guests agree that minutiae like the precise clocking (rotational orientation) of the sensing bulb or whether it's mounted horizontally or vertically tend to be overemphasized. The key is ensuring good thermal contact between the bulb and refrigerant line.
They dive into the operating principles of an expansion valve, explaining how it's essentially a balanced system of forces between the inlet (liquid) pressure, the outlet (suction) pressure, the pressure in the sensing bulb corresponding to superheat, and the adjustable spring force. Getting the superheat dialed in properly is crucial for efficient system operation.
The experts share valuable insights on best practices like avoiding heat damage during brazing, using the right valve for the application, not adjusting the valve unnecessarily, allowing stable operation before making adjustments, and considerations like external equalizers. Real-world examples and demonstrations with failed valve components illustrate the importance of proper installation and maintenance.
Topics covered include:
Common expansion valve myths and overemphasized factors How an expansion valve works and the balanced forces involved Superheat, hunting, and minimum stable superheat Recommended bulb insulation practices for different applications Proper bulb mounting, clamping techniques, and thermal contact When and how to adjust the valve (or not) Effects of plugged external equalizers and pressure drops Selecting the right valve size and type (bleed vs hard shutoff) Common installation errors like reverse flow direction Troubleshooting tips for various systems and scenarios Importance of airflow, load conditions, and other system factors  
Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool. 
Learn more about the 5th Annual HVACR Training Symposium at https://hvacrschool.com/Symposium24.
If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.”
Subscribe to our YouTube channel at https://www.youtube.com/@HVACS. 
Check out our handy calculators HERE or on the HVAC School Mobile App (Google Play Store or App Store).

In this short podcast episode, Bryan answers an audience member's question and explains how to learn superheat & subcooling, two fundamental aspects of the HVAC/R trade. You can submit questions of your own at https://www.speakpipe.com/hvacschool. 
Saturation is when a substance is in the liquid and vapor state in the same place. Eugene Silberstein likes to help us envision it by encouraging us to think of a horizon line on the ocean; anything below it is fully liquid (subcooled, what a submarine would travel through), and anything above it is a vapor (superheated, which a flying superhero would travel through).
Superheat and subcooling can tell you a bit about how the HVAC system's main components are operating. High superheat indicates that there's more vapor in the evaporator, and you're not getting as much efficiency out of your evaporator as you probably could. High subcooling indicates that you're stacking more liquid refrigerant in the condenser, which can be good for efficiency but may also reduce the area of the condenser dedicated to condensing the refrigerant.
Superheat and subcooling are NOT just there to help you set the charge; they can tell you a lot about a system and its components. 
 
Ty Branaman has a great webpage about superheat, subcooling, and saturation at https://www.love2hvac.com/saturation-superheat-subcooling. You can also visit his YouTube channel at https://www.youtube.com/@love2hvac. 
Craig Migliaccio (AC Service Tech) also has an excellent book on the topic, which you can learn more about at https://www.acservicetech.com/ac-book. You can also visit his YouTube channel at https://www.youtube.com/@acservicetechchannel.  
Learn more about the 5th Annual HVACR Training Symposium at https://hvacrschool.com/Symposium24.
If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.”
Subscribe to our YouTube channel at https://www.youtube.com/@HVACS. 
Check out our handy calculators HERE or on the HVAC School Mobile App (Google Play Store or App Store).

In this episode of the HVAC School Podcast, Bryan Orr and Trevor Matthews delve into the importance of setting goals, focusing on them, and taking actionable steps to achieve them. They emphasize that goal-setting is crucial for personal and professional growth and that it requires introspection, prioritization, and sacrifice.
Trevor shares his experience of setting a goal to buy his first house and how writing down the specifics, such as the number of bedrooms and bathrooms, helped him achieve that goal within a few years. He stresses the need to start small, with easily achievable goals, and then gradually build up to larger, more ambitious ones.
Bryan and Trevor also discuss the importance of finding your "why" – the deeper motivation behind your goals – as it provides the drive and determination to stay focused and overcome obstacles. They suggest techniques like the "five levels of why" and creating vision boards to help clarify and visualize your goals.
Here are some key topics covered in the podcast:
·        The importance of assessing what you truly want and setting clear goals
·        Techniques for finding your "why" and staying motivated
·        Prioritizing tasks and managing distractions to maintain focus
·        Setting short-term and long-term goals, both personal and professional
·        The power of small wins and positive reinforcement
·        Investing in yourself and taking ownership of your career growth
·        Managing expectations and aligning your goals with your employer's
·        Overcoming the mindset of waiting for the "right" time to start
·        Practical strategies like scheduling, time-blocking, and budgeting to achieve financial goals
Overall, the podcast encourages listeners to take control of their lives, continuously learn and grow, and make consistent progress toward their goals, no matter how small the steps may seem.
 
Check out Trevor's Refrigeration Mentor program at https://refrigerationmentor.com/.  
Learn more about the 5th Annual HVACR Training Symposium at https://hvacrschool.com/Symposium24.
If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.”
Subscribe to our YouTube channel at https://www.youtube.com/@HVACS. 
Check out our handy calculators HERE or on the HVAC School Mobile App (Google Play Store or App Store).

In this short podcast episode, Bryan talks about when to switch to emergency heat. He talks about coefficient of performance (COP) and how it's a deciding factor when to run emergency heat, which is when a system ONLY runs the backup heat; it doesn't use it as supplementary heat.
When we have a heat pump with backup electric heat, we shouldn't ever rely just on emergency heat; we want the heat pump to run. Electric heat is just designed to supplement the heat pump's heating because it's inefficient. Hybrid or dual-fuel systems can use gas or hydronic fuel-based heat, and they work well on their own (such as if the heat pump is broken). You can't usually run the fuel-based emergency heat at the same time as your heat pump, so it makes sense to run just the emergency heat if it is fuel-based.
The thermal balance point is the point at which the heat pump can no longer keep up with the heating load by itself; the temperature in the space will start to drop, but the heat pump will still produce heat. The thermal balance point can give us a clue about client comfort, not efficiency. COP is a measure of efficiency, and an electric heater has a COP of 1. A heat pump with a COP above 1 saves energy (compared to using just electric heat). COP is the heat delivered in BTUs divided by the energy supplied; it's a ratio.
 
You can read the "Good COP - Bad COP" tech tip at https://hvacrschool.com/good-cop-bad-cop/. 
Learn more about the 5th Annual HVACR Training Symposium at https://hvacrschool.com/Symposium24.
If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.”
Subscribe to our YouTube channel at https://www.youtube.com/@HVACS. 
Check out our handy calculators HERE or on the HVAC School Mobile App (Google Play Store or App Store).

Shelby Breger, co-founder of Conduit Tech, joins Bryan Orr on the HVAC School Podcast to discuss her company's innovative lidar-enabled design and sales software tool for HVAC contractors.
Conduit Tech's software utilizes lidar sensors in iPads and iPhones to scan homes and create 3D models and 2D floor plans. It overlays load calculations factoring in property data, orientation, cooling/heating degree days, and building materials. This allows contractors to perform detailed load calculations on-site in just 15 minutes or less while engaging homeowners visually.
Breger explains that the core goal is to empower contractors to deliver better-designed systems more efficiently while enhancing the customer experience. Homeowners get to see the level of work and customization involved, building appreciation for the contractor's services. The visuals help communicate potential comfort issues and how the proposed solution uniquely addresses their home's needs.
Breger emphasizes that Conduit Tech is focused on solving fundamental industry pain points identified through continuous feedback from their contractor user base. The software has evolved to provide more flexibility to adapt to the realities of home visits. New features like augmented reality equipment visualization further enhance the customer engagement capabilities.
Topics covered include:
How Conduit Tech's lidar scanning and modeling works Using the software for room-by-room or whole home load calculations Integrating data sources like property records, ASHRAE design conditions, etc. Aligning with ACCA Manual J methodologies and certifications Improving load calculation accuracy through real-world monitoring Leveraging technology to streamline processes across sales, design, and installation The value proposition for contractors and homeowners Roadmap for adding features based on user feedback How contractors can get started with Conduit Tech's software  
Contractors interested in trying out Conduit Tech can visit https://www.getconduit.com/, or they can email shelby@getconduit.com or info@getconduit.com to learn more and schedule a demo.
Learn more about the 5th Annual HVACR Training Symposium at https://hvacrschool.com/Symposium24.
If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.”
Subscribe to our YouTube channel at https://www.youtube.com/@HVACS. 
Check out our handy calculators HERE or on the HVAC School Mobile App (Google Play Store or App Store).