HVAC School - For Techs, By Techs

In this short podcast episode, Bryan dives into NTC, PTC, and thermocouples. NTC and PTC are two types of thermistors, and all three tools are used to sense temperature. Thermistors are resistors that change their resistance based on a change in temperature. They must be powered, and the resistance changes the amperage. You can test a thermistor with an ohmmeter at a fixed temperature. The best temperature for testing is the thermistor's rated temperature, typically 77 degrees Fahrenheit. NTC thermistors are negative temperature coefficient thermistors; as the temperature decreases, the resistance increases, and vice versa. Temperature and resistance are inversely proportional. PTC thermistors are positive temperature coefficient thermistors, and the temperature and resistance are directly proportional. These types of thermistors are usually quite accurate, and they are common in thermostats. PTCs are common in certain types of hard start kits, in which they help take the start capacitor or start winding out of the circuit. They have the same function as a potential relay. The resistance increases with temperature, meaning the PTC gets hotter and raises its resistance until the circuit opens, but it takes a while to reset because it needs to cool down. Thermocouples work because they generate a voltage in response to a temperature difference between two dissimilar metals. This phenomenon is called the Seebeck effect. Thermocouples are hardy devices used in temperature-sensing equipment, and they measure over a wider range than thermistors. However, thermocouples tend to be less accurate than thermistors. 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 episode focuses on practical ways to save energy with grocery store refrigeration systems, with Matthew Taylor from Kalos Services sharing insights from both a technician and business owner perspective. The hosts emphasize that proper, consistent operation and preventing short cycling of compressors can have a major impact as the largest power consumers. Proper control strategies, like ensuring evaporator pressure regulators (EPRs) are working, maintaining subcooling, and preventing excessive compressor staging and rapid on/off cycling, are critical for reducing energy consumption. Often, technicians troubleshooting issues bypass these controls when they could be tuned and optimized instead. Matthew stresses the financial benefit for owners when technicians understand the original design intent and how to optimize performance, not just apply a band-aid fix to problems. He advises business owners to track power bill anomalies to catch inefficiencies. Other key factors covered: ensuring clean evaporator coils, properly functioning doors/curtains, humidity control, condensed maintenance, addressing core issues like suction pressure rather than quick fixes, compression ratio impacts, and coordinating refrigeration with HVAC equipment. Implementing complex new networked equipment has trade-offs as well - while offering more data, it requires different skill sets to leverage. Topics covered: Optimizing EPRs and refrigeration controls Preventing short cycling and improper staging Following the original system design intent Tracking power bills to catch system drift The impacts of evaporator coil cleanliness Building envelope considerations Humidity control relationship with refrigeration Compression ratio and suction pressure optimization Evaluating networked controls vs. ease of maintenance Recommissioning 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).

The podcast is a conversation between Ed and Bryan about using the ACCA Residential Plans Examiner Review Form, an ACCA form you probably never heard of, to demonstrate that proper HVAC system design procedures were followed based on the Manual J, Manual S, and Manual D guidelines. Ed introduces the Residential Plans Examiner Review Form as a one-page document that allows contractors to show they gathered the minimum necessary information to complete a proper HVAC system design. The form doesn't teach how to actually do the design calculations but can help explain the design to others not familiar with it, like code officials asking for documentation. The form is meant as a bridge to facilitate communication between contractors and authorities having jurisdiction (AHJs). Ed shares stories of using the form successfully to work with code officials and gain approval. Bryan asks clarifying questions about the intended audience for the form - whether for residential new construction only or also replacement - since it references the duct design Manual D procedures. Ed explains the full manuals would likely only apply to new construction and add-ons, but elements could apply to replacements if load calculations are required locally. The details depend on the specific project and jurisdiction. Topics covered: Purpose and use of ACCA Residential Plans Examiner Review Form Information that the form documents from Manual J, Manual S, and Manual D The form's audience (primarily code officials/AHJs, but it's also helpful for contractors) Applicability for residential new construction, add-ons, and some replacements Stories of working with local code officials using the standard form Where to access online - ACCA website and search by full name Access the document information and examples online HERE and learn more about ACCA at https://acca.org/home. 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 HVAC podcast episode, hosts Bryan Orr and Matthew Taylor (refrigeration leader and trainer at Kalos Services) discuss oil management and considerations in supermarket refrigeration systems, with a focus on solving & preventing oil issues. They talk about the importance of stable system operation and how oil flows through both active and passive systems in these larger built-up racks. Matthew explains that in a rack system, oil is actively separated and returned to the compressors through a dedicated system. However, not all oil gets captured this way, so the passive system of oil returning through the refrigeration cycle still occurs. Problems can arise in either system, leading to compressors locking out. Matthew stresses properly setting and regulating EPR valves to minimize load fluctuations that impact system stability. Common issues covered include clogged oil separators, misadjusted or damaged oil controls, changes in suction pressure affecting oil flow, the impact of floating suction pressures, and troubleshooting overfilled compressors. Matthew offers tips like feeling the oil separator line temperature and using working racks as a guide when unsure of proper settings. The discussion highlights how poor defrost performance can indicate oil trapping issues. Matthew and Bryan also cover: Active vs passive oil management in racks Setting EPR valves for stable operation Clogged oil separators and failed floats Suction pressure fluctuations disrupting oil flow Strategies for floating suction pressures Steps for readjusting oil controls Signs of oil trapping issues in the refrigeration cycle Using working racks to guide troubleshooting 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 podcast, Bryan and Clifton discuss the upcoming transition to A2L refrigerants, like R-32 and R-454B, and what A2L mitigation is going to look like. These mildly flammable refrigerants will be used in place of R-410A for residential air conditioning systems due to an HFC phase-down driven by legislation and international agreements. They explain what mitigation means with A2L systems - sensors will detect refrigerant leaks, and the system will shut off and turn on the blower fan to dissipate any leaked refrigerant. The mitigation helps minimize flammability risk. They note the new A2L refrigerants contain no propane despite some misconceptions. The fundamentals of safe installation, service, and repair remain similar but will be absolutely required for A2Ls versus more loosely followed with previous refrigerants. Taking proper time and care is crucial. Bryan and Clifton then discuss the education, training, and resources available from ESCO Group to help contractors prepare for this transition. Key topics covered: Upcoming transition to A2L refrigerants R-32 and R-454B Phase down of R-410A driven by legislation and international agreements Definition and purpose of mitigation used with A2L air conditioners Misconception that new refrigerants contain propane Fundamentals of safe installation and service remain similar but even more vital Taking the proper time and avoiding rushing is crucial for safety Education, training, and resources available from ESCO Group Preparing the HVAC industry for the refrigerant transition The yearly AHR Expo and HVAC Excellence Conference You can learn more about ESCO Institute at https://www.escogroup.org/ and explore the HVACR Learning Network at https://hvacr.elearn.network/. 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).

Bryan and Kevin discuss indoor air quality solutions in terms of healthy air supplements vs. pillars of IAQ, drawing an analogy between IAQ supplements like electronic air cleaners and fitness supplements. They talk about why discussing these supplemental products can be controversial since many companies profit from selling them. However, the fundamentals of good IAQ - ventilation, filtration, and humidity control - are proven to work well, just as diet, exercise, and hydration promote good health. Most contractors focus more conversations and training around supplemental IAQ products versus the fundamentals, which parallels how society embraces fitness supplements over proper diet and exercise. However, a growing group of homeowners want real solutions, and the fundamentals often solve problems better and with less risk than just adding devices. Measuring IAQ and using data-driven diagnoses lead to more targeted solutions, too. The fitness analogy applies well - you don't jump to supplements first, and adding more supplements isn't always better or healthier. Dosage and application really matter. Contractors should consider focusing 80% on IAQ fundamentals over supplemental products to best serve customers. Topics covered: Why discussing IAQ supplements is controversial Fundamentals of good IAQ: ventilation, filtration, humidity control Parallels between IAQ supplements and fitness supplements Reliance on and training around supplemental products versus fundamentals Growing consumer demand for real IAQ solutions Using IAQ monitoring and measurement for better solutions How having more supplements or devices isn't always better Dosage and proper application really matter Shifting contractor focus to 80% on IAQ fundamentals versus supplemental products You can learn more about HAVEN products at https://haveniaq.com/ or become a HAVEN pro at https://pro.haveniaq.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 episode, Bryan discusses the unique features of hot deck, cold deck systems. These systems have separate heating and cooling components (if not entire systems). Older systems may have completely separate duct systems: one for heating and one for cooling. These ducts would go to each space, and you'd essentially have twice the ductwork you'd expect nowadays. Some systems also have a separate hot deck and cold deck in a single appliance (a bit like gas furnaces with case coils). We also use the term "hot deck, cold deck" to refer to systems with secondary fluid in a single appliance that produces heating and cooling. Heat recovery or heat-pump chillers use secondary fluids to carry heat around (these fluids don't expand and change state like refrigerant). A traditional chiller is often used in combination with a boiler system, and both can be shut on or off; this configuration can be tricky in shoulder seasons, and a hot deck, cold deck system could be beneficial instead. Buffer tanks also allow energy to be stored in a hot deck, cold deck configuration. Hot deck, cold deck systems may also be beneficial in humid climates if the cooling component is before the heating component; the system could provide heating, cooling, and dehumidification. You could also use hot deck, cold deck systems for domestic hot water (via a heat exchanger) and cold plunges. It's even possible to use flammable refrigerants in heat recovery chillers that use this configuration. 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 HVAC School, hosts Bryan Orr and Bert discuss practical tips for preventing callbacks and failed inspections in residential HVAC installs and maintenance. Bryan and Bert stress the importance of getting the basics right, like properly cleaning condensate drains, ensuring proper drain pitch, and sealing ducts completely before relying on tapes and mastic to cover gaps. They emphasize verifying full system operation at the end of a job, from checking that drains flow freely to testing float switches and pressure testing for leaks. Bryan and Bert also cover wire and breaker sizing for equipment changes, securing disconnects, proper thermostat wall seals, inspecting joints with bubbles to find microscopic leaks, and more thorough evacuations and leak checks. Throughout the casual, conversational show, the hosts inject colorful commentary on doing quality work with a little sarcasm, including praising the merits of duct board and flex ducts. The tone is partly tongue-in-cheek but drives home the point that shortcuts lead to callbacks and leave clients dissatisfied. Bert and Bryan also discuss: Becoming masters of the obvious Common condensate line issues The issues with double traps Ensuring adequate filter access for the customer Wiring float switches in series vs. in parallel Sealing ductwork effectively Using your senses to find airflow leaks in the ductwork Pressure testing for refrigerant leaks Common leak points in systems and their causes Correct electrical setup and markings Securing outdoor unit placement Sealing thermostat wall penetrations Thorough evacuation and leak checks 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 episode, Bryan talks about the situations when permits are not needed to install HVAC/R (or HVAC/R-related) components. A few codes are universal in residential HVAC, including the International Residential Code (IRC) and the International Mechanical Code (IMC). The local municipality, also known as the authority having jurisdiction (AHJ), chooses which codes to adopt. You do not need a permit to install plug-in, cord-connected appliances. However, you need UL-listed plugs. You can also replace plugs without needing a permit, but the ratings need to be correct. Anything less than 25v that doesn't put out more than 50 watts of energy also doesn't require a permit. Thermostats and many IAQ accessories, including UV lights, fall into this category. Portable heating and ventilation appliances, including space heaters and portable cooling units or dehumidifiers, also don't require permits. Evaporative or "swamp" coolers also don't need a permit for installation. Self-contained units with 10 pounds or less of refrigerant and are actuated by motors with However, emergency replacements and repairs (per R105.2.1 in the IRC) also don't require a permit, at least not before performing the work. The only condition is that the permit application must be submitted to the AHJ within the next business day. This rule can come in handy when you can't wait for the permit submission process and need to do an emergency repair or changeout. 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 podcast, Bryan Orr and Bert discuss various aspects of pool heaters, focusing on issues that make them different from typical HVAC systems. They cover the basics of pool heaters - the main types (heat pumps and gas heaters) and how they operate similarly or differently from things HVAC techs work on regularly. The bulk of the 45-minute podcast looks at common service and troubleshooting situations with pool heaters, which are usually installed by pool contractors initially and not HVAC contractors. Bryan and Bert talk through typical causes of common error codes and problems like units frequently going out on high pressure. They cover water flow issues and the role of pressure versus flow switches, the sizing and limitations of heat pumps, low ambient operation challenges, freeze protection, and proper refrigerant charging. There is also a good amount of discussion on gas pool heaters - frequent component failures due to heat and corrosion issues, piping considerations due to their large BTU capacity, and combustion troubleshooting basics. Throughout the casual discussion, both hosts interject humor and personal stories related to their dealings with pool heater equipment, clients, and installations over the years. The overall message is that while heat pumps and gas pool heaters have some specialized considerations, much of the core knowledge needed to service them comes from foundational HVAC systems understanding combined with an awareness of the unique aspects covered in detail during this episode. Topics Covered: Types of pool heaters How heat pump and gas pool heater operation compare to HVAC Typical installation and service providers Key components and design aspects Common high-pressure issues and troubleshooting water flow problems Low ambient operation challenges Refrigerant charging considerations Gas piping sizing for large BTU appliances Corrosion issues and component failures Combustion testing basics 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).