HVAC School - For Techs, By Techs

Latest Episodes:

Diagnose and Prevent Compressor Short Cycling Mar 11, 2021

Show notes

In this podcast episode, Bryan and Trevor Matthews discuss compressor short cycling. They discuss how to diagnose and prevent that issue. Trevor and Bryan primarily refer to the Bulletin AE17-1262 throughout this episode, which you can find HERE.

Compressor misdiagnosis is very common, but we generally encounter two types of compressor failures: electrical failures and lubrication failures. Short cycling causes a loss of oil in the compressor, which may lead to lubrication-related failure. Each time a compressor starts, there is a reduction in suction pressure; the pressure drop then causes the saturation pressure to drop. That can then cause the oil to flash and shoot out of the compressor.

Short cycling has many potential causes, including protectors, thermostats, low and high-pressure controls, oversized condensers, and oversized compressors. In some cases, the controls can also cause operational short cycling to meet customer demands (or failure to match the load). Each manufacturer may have a different acceptable range of starts per hour, but some customers may request more or fewer starts than recommended.

Cycle length and frequency are keys to system longevity. So, we can prevent compressor short cycling by keeping the system operating within the manufacturer's specs. There are also several components that can help manage the factors that cause short cycling, including bleed resistors on capacitors, which manage relay operation. Troubleshooting is also one of the main preventative measures; if you replace the compressor without troubleshooting, your new compressor may short cycle and fail prematurely just like the first one.

Trevor and Bryan also discuss:

Oil behavior and losses
Customer demands
Manufacturer specs and communication
Oversized compressor issues
Internal low-leak discharge check valves
Digital scroll compressors in a tandem set
Short cycling's effects on the whole system
Airflow and pressure
Load matching

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.

Recovery Tips and Best Practices w/ AC Service Tech Mar 04, 2021

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In this podcast episode, Bryan and Craig Migliaccio (AC Service Tech) discuss some HVACR recovery tips and best practices.

When you select a recovery tank, you need to know which refrigerant is in the tank. So, it's a good idea to make sure you label each recovery cylinder. You don't want to contaminate refrigerant in the recovery tank, use a recovery tank with contaminated refrigerant, or have too much air inside the cylinder. If the tank is empty, you'll have to pull a vacuum on it before you use it for the first time.

Tank fill can be a tricky business. You have the tare weight and water capacity, which you can use to determine the maximum refrigerant fill (factoring in the refrigerant's specific gravity at 130 degrees and the 80% capacity). Weighing in the charge is important so that you stay within an appropriate range as not to build up hydrostatic pressure and risk injury.

Recovery machines will give you the quickest recoveries. (When using one of those, you can extend your machine's life by using a filter drier during recovery.) However, you can also keep the pressure of the tank low during recovery; one of our best tips is to put the cylinder in an ice bucket during recovery. Regardless of what you use for recovery, you ALWAYS want to use a scale to weigh the tank as you recover refrigerant.

Craig and Bryan also discuss:

Hydrostatic pressure
Figuring out the refrigerant type in an unmarked tank
Contamination
Core removal
Waterproof scales
Leaks and low refrigerant charge conditions
Pulling from the liquid and suction lines
De minimis venting

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.

Swaging and Flaring Tips w/ AC Service Tech Feb 25, 2021

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In this episode, Bryan and Craig Migliaccio (AC Service Tech) talk about some best practices you can use while swaging and flaring copper.

There are a few different ways you can flare copper. Craig likes using a round deburring tool before flaring the copper. After the burr has been cleanly removed, Craig likes using an eccentric flaring tool for the actual flaring. Bryan's favorite flaring tool is the NAVAC battery-powered flaring tool for quick, accurate flares. Both Craig and Bryan agree that it's better not to deburr if you're likely to drop the burr or copper shavings into the tubing.

You can also use a tiny bit of Refrigeration Technologies Nylog on the flare face to make sure that the contact is sufficient and secure.

Along with flaring, we also have tube expansion or swaging. There are several tools you can use, including drill, hammer, and block swages. Craig likes to avoid swaging tools that leave large gaps; adding heat to make the swaging process smoother may result in oxidation. He prefers using a drill swage on downward-facing tubes; the drill swage can provide friction and heat while keeping the copper tube clean. Overall, Craig doesn't have a favorite swaging tool; he acknowledges that each swaging tool has an appropriate application. It's NOT a good idea to use a tube expander near the compressor.

Craig and Bryan also discuss:

Deburring in difficult situations
Over-reaming with blade deburring tools
Flares on higher-pressure systems
Comparing the flare size to the flare adapter size
Old flaring tools, new flares
Ductless or mini-split systems
Cleaning the lines if you drop anything inside of them
When to use a fitting

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.

Are Contactors Obsolete? (SureSwitch) Feb 24, 2021

Show notes

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.

Don't Miss The Tech Training Event Feb 23, 2021

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Other Uses for Nitrogen - Short 113 Feb 23, 2021

Show notes

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.

Is Ultrasonic Leak Detection Best? Feb 18, 2021

Show notes

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.

Universal Defrost Controls w/ Jim Fultz Feb 17, 2021

Show notes

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.

Maybe Don't Buy New Tools - Short 112 Feb 16, 2021

Show notes

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.

How Craig Became "AC Service Tech" Feb 11, 2021

Show notes

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: