HVAC School - For Techs, By Techs

In this podcast episode, Bryan and Jim Fultz discuss the White-Rodgers SureSwitch and determine whether contactors are obsolete or not. Contactors are electrical controls; they started off very expensive and usually outlasted equipment, so they are currently smaller, cheaper, and less durable than they used to be. Modern contactors have open contacts and are susceptible to insect damage. Sometimes, an electrical arc can cause contactor pitting, which can weld the points together and render the contacts useless. The SureSwitch is more than a contactor; it is also a brownout monitor, short cycle timer, and a random start timer that helps with brownout recovery. The installation instructions are also thorough and include helpful information like torque specs. It also has a high-visibility LED. The SureSwitch has sealed contacts, so insects can't get to the contact points and cause pitting or failure to close. There is also a latching relay feature, which prevents chattering at lower voltages; the points stay fully closed. The SureSwitch also has a microprocessor that monitors the electrical current going inside the relay. If that microprocessor detects arcing, it knows that the contact points had closed somewhere close to the peak of the arc, and it will adjust itself accordingly. The SureSwitch now has a multi-volt coil, so it can work in residential AND commercial HVAC. Instead of being limited to single-phase 240v applications, we can now apply that contactor to three-phase and 208v applications. Jim and Bryan also discuss: Shunts Contactor chattering Opening or closing at the zero point of the sine wave Mounting points Why insects like to get into contactors Contact configuration Time delays Maintenance contracts and customer loyalty incentives Short cycling for testing purposes   Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this episode, Bryan and Craig Migliaccio (AC Service Tech) discuss all the ways that nitrogen can make your job easier. Nitrogen is an inert gas that we can use for purging refrigerant lines and completing scale-free brazing jobs. As techs, we should have at least one inert gas in our trucks to help us do the best job possible. We can use inert gases for purging refrigerant from tubing, flowing and preventing oxidation while brazing, and pressurizing a system for leak detection or a pressure test. You'll also find nitrogen useful for getting oil out of the way before pulling a vacuum. You can also use nitrogen to help clean out a drain line. However, you'll want to be careful; if the PVC pipe isn't secure, you could create leaks (or a total blowout). You can cause severe structural damage if you flow a compressed gas under too much pressure. In some cases, we also use nitrogen to pressurize a gas line (including propane or natural gas lines). We can pressurize that to about 6 PSI to get the pressure up to a more desirable level. (Not to mention, we can reinflate tires with nitrogen, though that's not a strictly HVAC-related application.) Outdoor units may be installed near a dryer vent, which increases the risk of the unit getting dirty. When that's the case, you can use nitrogen to blow off any of the lint and debris. Overall, you can use nitrogen for applications where you'd usually use compressed air. Anytime you work with any kind of inert gas, you need a flow meter and regulator; a normal gauge manifold just won't cut it. Make sure you flow the gases at appropriate pressures, too.   Check out Craig's website at acservicetech.com. Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this podcast episode, Bryan and Craig Migliaccio, AC Service Tech, talk about ultrasonic leak detection. They discuss its effectiveness and if it's worth the hype. Ultrasonic leak detection works best when there's oil on the inside of the tubing; it works best when the system is equalizing after shutoff. Oil or moisture can create a squealing noise, which is an indicator of a leak. Ultimately, lack of success with ultrasonic leak detection comes down to user discomfort and a lack of proficiency. Bubbles alone won't be enough, so it's good to use an ultrasonic detector, even if you need to use a heated-diode or infrared detector as a backup if you lack confidence. You can use nitrogen to assist with leak detection BEFORE refrigerant goes into the system; nitrogen is great because it is an inert gas. However, you must be careful with pressurization, as overpressurization may lead to leaks. You must also keep in mind that nitrogen is the dominant element in our atmosphere, so no leak detector would be able to sample nitrogen alone. If refrigerant is in the system, we can use heated-diode leak detection with relative ease. However, heated-diode leak detectors require a lot of maintenance. In any case, sensors must be matched to the refrigerant you're looking for. Infrared detectors generally work well, but they can be confusing and lead to errors. You must usually keep moving infrared thermometers to catch a leak accurately. Craig and Bryan also discuss: Various types of leak detectors Having confidence in your tools Pressure test vs. leak detection Using your senses first Sensor placement Stratus leak detector Reading the manual Servicing leak detectors Leak reactant (soap bubbles) limitations Relying on guesswork   Check out Craig's site at acservicetech.com. Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this podcast episode, Jim Fultz with White-Rodgers joins us to discuss universal defrost controls. He also explains when and why you might use universal controls. Bryan and Jim cover a universal defrost control for heat pumps (Model #: 47D01U-843). You can follow along by reading the manual HERE. Universal defrost controls can replace OEM defrost controls. Universal controls are sometimes more readily available than OEM parts, so they can be good repair options.  The White-Rodgers universal heat pump defrost control comes with the board, installation instructions, two wiring harnesses, two thermistor-style sensors, and a bag with screws, wire nuts, and other mounting materials. This particular control is compatible with 400 different product SKU numbers, so it's a versatile replacement. The display of the White-Rodgers universal heat pump defrost control gives a lot of feedback; it has orientation options and can communicate more information than mere flashing LEDs. You'll have to set the display orientation in an ideal position, but the controls will help you out with that. You'll also want to keep these defrost controls out of the sun, away from snow, and on the back of the unit. If you don't already have an outdoor coil temperature sensor set up, then you'll want to install the sensor at the bottom of the condensing unit coil. As far as the actual defrost options go, you can set seven different options that correspond to specific manufacturers' controls (OEM Quick Setup). The short cycle time, reversing valve, time delay, and maximum defrost times can be tailored to each manufacturer's equipment. Jim and Bryan also discuss: Spade connections Wiring diagrams for the universal defrost control Outdoor thermostat and electric heat Oil behavior Demand defrost Annual energy savings Table settings Reversing valve shift delay time Auxiliary heat Low-temperature compressor cutout Brownout protection Force-initiation   Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this short podcast episode, Bryan and Craig Migliaccio discuss why you maybe don't want to buy new tools. Whenever you get new tools, you have to account for a learning curve and potential change to your practices. Changing your practices and procedures isn't necessarily a bad thing, but you have to practice with the tool and account for different setup and cleanup procedures. However, once you find a good process, you don't want to mess with it too much. You will also want to account for changes to your tool maintenance procedures. When you go from analog to digital tools, you want to make sure you understand exactly what you're measuring. So, Craig recommends spending time with compound gauge sets and to understand how to find superheat and subcooling before you start using digital gauges. It's best to have some good tactile experience troubleshooting a system with analog gauges. Probes have several advantages, including their Bluetooth compatibility, reduction in refrigerant losses, eliminated risk of contamination, and accuracy. However, without a solid foundation in troubleshooting, switching to probes may make you a bit inefficient. Calibration is another factor to consider with new tools. You must know how (and when) to calibrate your tools. Calibration is part of maintenance, and it's something you need to account for whenever you purchase a new tool and learn how to use and take care of it. Whenever you get a new tool, remember that you want consistency, efficiency, and positive outcomes for customers. Craig and Bryan also discuss: Pulling cores Evacuation and recovery Accuracy of sensor technologies Finding the tools that work for YOU Muscle memory with tools Ideal applications   Check out Craig's work at acservicetech.com. Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this podcast episode, we find out how Craig Migliaccio became "AC Service Tech." He makes educational materials and has even written a book. You can check out his website HERE and his YouTube channel, AC Service Tech, HERE. Craig got into the HVAC trade after coming from a construction background; he mostly worked on existing homes and had to handle some HVAC tasks. From there, he got into service and went headfirst into the HVAC industry by starting his own business: a carpentry and HVAC business. Craig also got into the teaching side of the trade, starting off by becoming a maintenance supervisor at a school. As a teacher, he emphasized the importance of basic mechanical skills when he taught high schoolers and young adults. He also noticed that a lot of people were interested in the HVAC industry, so that's what he focused on as a teacher. Craig started making his own videos to introduce students to a topic, and that's where his story as AC Service Tech began. In the classroom, Craig drew from many different resources. So, he decided to continue adding to his knowledge. He eventually compiled his knowledge and began making his own resources. As a content creator, Craig is more independent and less of a collaborator, but he still manages to have an impact on others. He has also published a book (Refrigerant Charging and Service Procedures for Air Conditioning) and a workbook, which are valuable teaching and learning tools. Bryan and Craig also discuss: Obtaining knowledge and building skills Figuring out what you don't know as an instructor Sequence of instruction Making an impact as a writer and instructor Community vs. substance in content creation Using your knowledge to help others Craig's available educational resources   Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this short podcast episode, Bryan and Craig Migliaccio discuss the skills and knowledge you should have to start in the HVAC industry. Of course, basic mechanical skills and knowledge are important before you get into the HVAC trade. You'll greatly benefit from knowing where and how to hammer nails, tighten screws, and identify all sorts of tools. When getting into the HVAC industry, one of the low-hanging fruits that you need to consider is your sheet metal skills. Know how to cut sheet metal, use shears, use a duct knife, and make a decent sheet metal job. Take shop classes, work on cars, and get more experience to work on your mechanical skills and tool knowledge. A basic sense of maturity is also crucial for getting into the HVAC industry. You have to be able to work hard and feel some sort of satisfaction from working hard. The HVAC trade is also full of self-starters, so it's best that you're a self-starter when it comes to basic life skills. The location where you will work in HVAC is also relevant. Make sure you have regional knowledge of building design and HVAC infrastructure (duct design, system types, joist orientation, etc.). Take an interest in local homes; look for supply and return registers. Know the HVAC equipment you will be working on and where it will be located in many buildings. It's also good to research terminology and know what you're talking about before you begin applying for HVAC technician/installer jobs. Craig and Bryan also discuss: The problem of the word "should" Using saws and drills Solving everyday mechanical problems Sensing maturity Researching companies before you apply Watching videos and reading books Work ethic and desire to learn   Buy Craig's book HERE and his YouTube channel HERE. Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this podcast episode, Bryan and Trevor Matthews of Emerson Canada discuss strategies for controlling liquid refrigerant in A/C and refrigeration systems. They also read through the AE22-1182 bulletin, which you can find HERE. Liquid refrigerant is one of the most common causes of compressor damage and even failure. It can also cause a loss of oil, which leads to reduced lubrication and subsequent damage. Compressors are vapor pumps, and they are not designed to handle much liquid refrigerant at all. Off-cycle refrigerant migration is one of the main causes of liquid refrigerant reaching the compressor. Controlling liquid refrigerant in the off cycle is important because oil can also saturate that liquid refrigerant inside that compressor. That can cause a severe problem when the compressor starts up again. However, crankcase heaters can keep refrigerant migration at bay, as the refrigerant will be less likely to migrate and condense inside the compressor. Liquid line solenoid valves and pump down cycles prevent refrigerant from going into the evaporator during the off cycle. During a pump down cycle, the compressor pumps all the liquid refrigerant into the condenser and receiver. If anything leaks past the solenoid, the compressor keeps pumping the liquid out. It's also best practice to use a crankcase heater if you use a one-time pump down. Trevor and Bryan also discuss: How to navigate Copeland bulletins Oil miscibility with refrigerant vapor Oil viscosity and its effect on oil return Tripping oil pressure safeties Crankshafts and bearing wear Slugging vs. flood back Minimizing refrigerant charge Continuous vs. one-time pump down Compressor temperature and its effect on liquid refrigerant control Accumulators Overheating or carbonizing oil with crankcase heaters Oil separators   Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this short podcast episode, Bryan talks about the TXV power element or power head. He explains what it does and why it's important. A TXV power element threads onto the top of the valve, and it's where the sensing bulb attaches to the valve. It is the component that applies the opening force to the TXV. When you lose the charge in the element, it stops exerting an opening force on the valve. So, the valve completely shuts and doesn't allow refrigerant to get to the evaporator coil. You'll get high superheat and a starved evaporator. Whenever you're checking one of those elements, it would be wise to check for a leak. The capillary tube that goes between the bulb and the element is usually easy to diagnose. You can usually see cracks, leaks, or rubouts quite easily. (If you're used to working with TXVs, you may even be able to hear or feel when the bulb is light on charge.) Because the element threads to the valve, it is usually quite easy to replace without condemning the entire TXV. If you're not sure that the TXV power element is the issue, you'll want to turn the superheat adjustment nut to the fully counterclockwise position (fully open). Once you do that, verify that the superheat is still too high. Then, remove the bulb from the suction line and warm it up in your hand for a little while. If the element still has charge, you'll notice more opening force on the valve. If the valve doesn't change at all, then the power element is the most likely problem. You should also not be able to depress the TXV's diaphragm with your thumb; if you can depress the diaphragm, then the element has lost its charge.   Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.