HVAC School - For Techs, By Techs Bryan Orr

In this short episode, Bryan talks about wiring in condenser fan motors, including aftermarket motor considerations and the different wire configurations.
When condensing fan motors fail, we need to know what to use to replace them. We often use PSC motors, though in cases when we replace a motor with an ECM, we still need to match the horsepower despite the increased flexibility. The motors we typically keep on our truck are 1/3 or 1/6 HP motors. 
Frame size (diameter) and depth also come into play; you may encounter a 42-frame motor or a 48-frame motor. You can't replace an 825 RPM motor with a 1075 RPM one because the poles are different (6-pole vs. 8-pole). Single-phase 208/230v will be the most common motors in residential systems, and the phase and voltage must match. You should also know how to reverse a motor if it is reversible. The bearing type will have some tradeoffs; ball bearings last longer but are louder than sleeve bearings. 
3-wire and 4-wire condensing fan motors are essentially the same; the white wire and brown-and-white wire are essentially the same, as there is a jumper inside the motor. You can connect a 4-wire condenser to both sides of the capacitor; in any case, follow the wiring diagram.
When mounting a motor, make sure the wires are strapped properly. Then, remember to unplug the correct weep ports (opposite side of the shaft) to allow condensate to drain out.
 
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.

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This podcast episode focuses on the critical shortage of HVACR technicians and installers across the industry. The hosts discuss the massive gap that exists, with estimates of nearly 200,000 open roles expected in the next few years. They are joined by Lenny Diaddario from Copeland's contractor services department and Chris Harris from the educational nonprofit National Coalition of Certification Centers (NC3).
Lenny and Chris explain the various initiatives Copeland and NC3 have undertaken to help attract more people to the HVACR trades. This includes STEM education outreach to get kids interested from an early age, partnerships with organizations like SkillsUSA and PHCC, virtual reality training tools that allow interactive compressor teardowns, and comprehensive certification curricula developed in collaboration with subject matter experts and instructors.
One major program they highlight is the "train the trainer" events where instructors from trade schools can get certified on the Copeland curriculum over an intensive week. They then take that knowledge back to their schools to teach and certify students as Copeland technicians. The goal is to build a strong foundational workforce of certified HVACR professionals.
Topics covered include:
The severe shortage of HVACR technicians and the need to fill roles Changing the stigma around vocational education and trade schools Appeal of trades to younger generations for self-reliance Copeland's initiatives like STEM days, SkillsUSA, virtual reality trainers NC3's certification curricula and "train the trainer" instructor events Copeland's online/mobile training resources like apps and AI assistant In-person training courses offered ranging from 1 day to multi-day The long-term vision for socioeconomic impact through a skilled trades workforce  
Browse some of Copeland's training opportunities at https://www.copeland.com/en-us/training-support/hvacr-training. 
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.

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Check out our handy calculators here or on the HVAC School Mobile App for Apple and Android.

In this episode of the HVAC School Podcast, Bryan interviews Rachel Kaiser, a chemist with a passion for making science more accessible and understandable, especially when it comes to the topic of combustion. Rachel shares her background of how her family's restaurant business sparked her early interest in chemistry and the science behind mixing ingredients to produce desired results.
Rachel dives deep into explaining the fundamental chemistry behind the combustion process. She breaks down the three key components required for combustion to occur - fuel, oxygen, and a heat source - and how the ideal chemical reaction is represented. However, she emphasizes that in the real world, factors like using natural gas (a mixture of gases) as fuel instead of pure methane and air (also a mixture) as the oxygen source lead to incomplete and imperfect combustion reactions.
The discussion highlights the importance of combustion analysis and monitoring for byproducts like carbon monoxide (CO) and nitrogen oxides (NOx). Rachel stresses that testing is crucial not just for technician safety but to ensure proper combustion for occupants as well. High CO levels, for instance, indicate incomplete combustion and the likely presence of other undesirable compounds.
Topics covered include:
The chemistry definition of combustion/flame Ideal vs real-world combustion reactions The three requirements for combustion Natural gas as a fuel mixture Air as the oxygen source and mixing considerations Carbon monoxide and nitrogen oxides as byproducts The role of combustion analysis Using visuals/experiments to teach combustion chemistry Applying chemistry knowledge for troubleshooting  
Connect with Rachel on LinkedIn and ask her more about chemistry in HVAC HERE. You can also view her presentation from the 5th Annual HVACR Training Symposium and/or purchase your virtual ticket to all sessions HERE.
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.

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Check out our handy calculators here or on the HVAC School Mobile App for Apple and Android.

In this short episode of the HVAC School podcast, Bryan talks about hoses and their various types and applications, particularly focusing on NAVAC hoses.
Charging hoses (NAVAC: NH5 and NH5L) ideally shouldn't be longer than 5-6 feet, as the longer the hose, the more refrigerant it will hold. Manifold gauges also have leak points, so it's usually better to use probes instead of manifolds to help with charging. Charging hoses with ball valves (NH5S and NH5SC) can help you control the flow and are great for recovery. Whenever you use charging hoses, they will have a core depressor on one side only (usually the 45-degree side, if applicable); the right amount should be exposed, and the seal should be in good shape.
Larger-diameter hoses with higher burst pressure are advantageous for recovery (though it's better to have separate hoses for recovery and evacuation). Larger-diameter hoses of a shorter length will allow you to get a higher flow rate, including cases where you have 1/4" connectors (though the F1028 & F1029  Rapid Y connection fittings can help out with those cases where you have 1/4" connectors by giving you the ability to connect two 3/8" hoses); hoses with a diameter of 3/8" are usually the biggest recommended ones for recovery. NAVAC's recovery hoses are the NHR38AA and NHR38AB.
Evacuation hoses are even bigger. Some good evacuation hoses include the NH34AB and NH34AC; they are short 3/4" hoses that are vacuum-rated and quite flexible. NAVAC also has smaller hoses, which tend to look more like recovery hoses. You do not want to use 1/4" hoses and core depressors for evacuation, but they are good for charging.
 
Check out all of the hoses NAVAC has to offer at https://navacglobal.com/products-by-category/hoses-kits/. 
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.  

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Check out our handy calculators here or on the HVAC School Mobile App for Apple and Android.

In this episode of the HVAC School podcast, Bryan interviews Pat Ward, an HVAC technician who specializes in servicing and maintaining computer room air conditioning (CRAC) units for data centers. They dive deep into the unique challenges and setups involved in cooling these critical facilities.
Pat provides an overview of data centers, explaining that they are essentially industrial-scale computer rooms that generate immense amounts of heat from the servers and need precise environmental controls. CRAC units are specialized air conditioning systems designed to maintain the temperature and humidity within tight parameters suitable for electronic equipment.
Unlike typical comfort cooling, CRAC units supply air around 70°F to avoid excessive dehumidification. Humidity control is crucial, often requiring supplemental humidifiers or dehumidifiers. Pat discusses common configurations like air-cooled direct expansion (DX) units as well as chilled water systems with computer room air handlers (CRAHs). Redundancy is a major consideration, with units networked together to stage capacity and provide backup.
The conversation covers many other topics related to data center cooling such as:
Using economizers and free cooling with outdoor air when conditions allow Potential issues with mildly flammable refrigerants in these applications Typical maintenance tasks like coil cleaning, filter changes, and refrigerant checks Accessing and navigating the control systems which often require passwords Advice for technicians new to working on CRAC units, like studying the equipment layout The massive scale of large data center installations with arrays of 20+ CRAC units Causes of overheating and how to avoid them Growth opportunities in the CRAC niche of HVAC  
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.

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Check out our handy calculators here or on the HVAC School Mobile App for Apple and Android.

In Part 2 of the Rack Refrigeration Class at Kalos Services, Matthew Taylor discusses safeties, service, and more. Part 1 focuses more on the basic refrigeration circuit of a rack refrigeration system.
When safeties are piped together, we have to keep in mind that they're a bit more complex than most HVAC refrigeration systems, especially when it comes to the oil side. All of these safeties and their proper installation can be located on the wiring diagrams. Safeties often respond to pressure, both in the refrigerant circuit and the oil circuit, but they may also respond to amperage or temperature.
Each compressor on a rack has its own safety controls, but all compressor safeties should be wired in series. Overloads may measure temperature or amperage and break the circuit if it detects unsafe conditions. We also deploy demand cooling strategies to cool the compressor and help control compression ratios. We can also control capacity with staging strategies. Mechanical controls may be able to communicate with electronic controllers, but these cases are less common in conventional rack systems. 
Matthew also covers:
Pop-offs and high-pressure switches Overloads and misdiagnosed compressor failures Sentronic oil pressure controls Mechanical and electronic controls Adjusting metering devices Liquid and vapor injection Subcooling and interstage cooling Suction filters and when to use them Service valves, hoses, and depressing Schrader cores for checking charge Restrictions in the refrigerant circuit Accumulators Pressure transducers and troubleshooting Mechanical and electronic time delays Bypassing safeties in mission-critical applications Compressor staging and unloaders  
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.