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Latest Episodes:

Specifically About Heat - Short 131 Nov 09, 2021

Show notes

In this short podcast, Bryan goes over energy transfer and heat, specifically specific heat.

BTUs per ton is a common measurement; a BTU (British thermal unit) is the amount of heat it takes to raise the temperature of one pound of water by one degree Fahrenheit. 12,000 BTUs per hour is equal to one ton in heating or cooling technology. It takes one "ton" of heat to melt a ton of ice, but we kept the measurement and terminology as we moved away from using ice in industrial refrigeration.

When it comes to specific heat, we have to remember that one BTU has a different heating or cooling impact on different substances. Most fluids have a specific heat lower than water, meaning that one BTU of heat will result in more heat transfer in that substance than water. Air is one such fluid that has a lower specific heat than water (0.24 vs. 1); it's easier to heat air than water. However, the specific heat of vapors can change with temperature and pressure.

When we change a refrigerant from a liquid to a vapor in the evaporator coil, it will reach saturation before boiling. As the refrigerant boils, the temperature will stay the same because the absorbed heat will all contribute to the phase change as latent heat. Even though most refrigerants have low specific heat, direct expansion systems can still move a lot of heat because it takes a lot of latent heat to complete a phase change.

In other systems that don't use direct expansion (using glycol or water instead), specific heat is more integral to the effectiveness of heat transfer because latent heat isn't a factor in heat capacity.

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Check out our handy calculators HERE.

Check out information on the 2022 HVACR Training Symposium at https://hvacrschool.com/symposium/.

Pressure Measurement Pro Tips w/ Steve Rogers Nov 04, 2021

Show notes

In this podcast, Steve Rogers from The Energy Conservatory explains some pro tips for pressure measurement.

There are three common types of pressure measurements: absolute, gauge, and differential. Absolute pressure is the pressure in a particular space in reference to a complete vacuum. (All absolute measurements use the zero point as a reference.) Gauge pressure uses atmospheric pressure as a reference point (which varies with altitude and location). Differential pressure relies on two connections (one of them is a reference point to the other).

The Energy Conservatory recently designed a manometer (DG-8) that differs from the standard manometers. The purpose of that manometer is to make pressure measurements in a more cost-effective way. Most manometers have similar sensors (diaphragms move with pressure, and the measurement read is the resulting difference in resistance). However, the DG-8's methodology can help it yield much more accurate measurements.

When dealing with small pressure measurements (like Pascals), the DG-8 is one of the most accurate manometers you will find on the market.

When you look at room pressure, keep in mind that pressurizing one room will depressurize another. Temperature differences also impact the pressure, and the HVAC unit can cause differences in pressure to arise as a result of temperature differences. When you run the kitchen or bathroom exhaust and expel a lot of air in your home, you can also bring the home under negative pressure; that can even cause your water heater to backdraft.

Steve and Bryan also discuss:

Blower door manometers vs. DG-8 manometers
Pascal scale
Room pressures and air paths
Infiltration and its effect on load calculations
Dominant duct leakage
Combustion appliance zone (CAZ) testing
Mechanical ventilation and pressure
Orphaned water heaters
DG-8 and the TrueFlow grid

Learn more about the DG-8 HERE.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Check out our handy calculators HERE.

Check out information on the 2022 HVACR Training Symposium at https://hvacrschool.com/symposium/.

Copeland Reciprocating CS Compressors w/ Trevor Oct 28, 2021

Show notes

Trevor Matthews from Refrigeration Mentor comes on the podcast to talk about Copeland reciprocating CS compressors. He and Bryan cover Bulletin AE4-1433 (found HERE) as they look at the operating envelopes for the CS compressor.

The CS compressors are hermetic reciprocating compressors that can work with some of the newer refrigerants. You will likely see these compressors in applications with smaller tonnages.

You'll usually want to charge these compressors with liquid refrigerant. If you have more than 6 pounds of charge in the system, using an accumulator is recommended. Under those charge conditions, the system also needs a check valve between the receiver and the condenser.

Suction line pressure drop is one of the most important things to pay attention to in the system. Make sure the suction line is of an appropriate size, that filter-driers don't have restrictions, and that accumulators aren't clogged. Overall, many manufacturers recommend removing the duction driers to keep the pressure drop minimal.

The recommended runtime for these compressors is also very short, only 5 minutes. CS compressors should cycle no more than 12 times per hour, and the off-time between cycles should be a minimum of 10 seconds.

Before returning or replacing a compressor, make sure you check all of the electrical components, including the capacitor. If the compressor hums but has power, you could simply have a capacitor or potential relay issue.

Trevor and Bryan also discuss:

Return gas temperatures
Discharge line temperature
Compressor superheat and flooded conditions with refrigerant blends
Crankcase heaters
Pump-down recommendations to stop short cycling
Initial charge vs. recharge
Metering devices
Line sizing
Electrical shorts
Sticking relays
Single-phase vs. three-phase power
Megohm testing
Purging with and flowing nitrogen
Burnout cleanup procedures
Locking/tagging out equipment
Hard start kits, potential relays, and start capacitors

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Check out our handy calculators HERE.

Check out information on the 2022 HVACR Training Symposium at https://hvacrschool.com/symposium/.

Adiabatic Cooling - Short 130 Oct 26, 2021

Show notes

In this short podcast episode, Bryan explains the science behind adiabatic cooling. Adiabatic cooling occurs in specific HVAC/R applications and in our environment as air temperatures and pressures change.

When we think of cooling, we refer to the loss of heat; we are either referring to the change in the total BTU content of the air mass or the temperature change. Adiabatic cooling takes sensible heat and transforms it into latent heat.

The most simple forms of adiabatic cooling can be seen in cooling towers and swamp coolers. In evaporative or swamp coolers, you have a pad saturated with water, and air moves over it. When air moves over the media, some of the energy helps evaporate the moisture on the pads, so the air loses sensible heat and becomes cooler. The thermal enthalpy (total heat content) stays the same, but some of the sensible heat has transferred to latent heat.

Air that goes through a swamp cooler goes in with higher temperature and lower humidity, and it leaves with a lower temperature and higher humidity. The BTU content stays the same; the energy merely transforms. As a result, we usually only use swamp coolers in arid environments where higher humidity is desirable. You also can't compare these to compression-refrigeration systems because compression refrigeration aims to change the BTU content and is NOT adiabatic.

When we run air over an evaporator coil, some of the water vapor in the air condenses to liquid water in the drain pan. Some of the energy in the refrigerant changes the state of the water vapor to liquid water instead of changing the temperature. You'll see a lower delta T when your return relative humidity (RH) is higher.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Check out our handy calculators HERE.

Check out information on the 2022 HVACR Training Symposium at https://hvacrschool.com/symposium/.

Fighting Boredom at Work - Short 129 Oct 19, 2021

Show notes

In this short podcast episode, Bryan shares his top tips for fighting boredom at work. You can use these tips to help you get out of a rut if you don't feel productive or get bored easily.

The first tip for fighting boredom is to see the art or creativity in your work. Even in the HVAC industry, there are plenty of opportunities for artisan skills and craftsmanship. When you see your work as an art that you need to refine, it's easier to get engaged in your work and feel proud of it. That's especially true of tasks like duct strapping and brazing.

Another way to stop from getting bored is to do more things that challenge you. Being constantly challenged and being out of your comfort zone keeps you interested and can even spark a new passion.

Pursuing mastery allows you to focus on one particular skill or subject to become an expert. When you master a skill, you also become a marketable job candidate and can carve out a niche within your organization. Mastery is about going deep rather than wide, and more people will feel enriched by working towards mastery than others.

If you're a social person, finding a community can keep you from getting bored. When you have a community, you will be around people who have the same interests and experience the same challenges as you. So, you won't get bored from feeling alone.

Mentorship is another way to rekindle your passion. When you choose to invest in and guide less experienced people in the trade, you can feel a renewed sense of purpose in your work.

And if you're REALLY bored, you can change everything up entirely and try something new.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Check out our handy calculators HERE.

Check out information on the 2022 HVACR Training Symposium at hvacrschool.com/symposium/.

Review Of Vacuum For Service Revisted Oct 14, 2021

Show notes

In this podcast episode, Bryan goes through the addendum to the book Review of Vacuum for Service Engineers. He and Jim Bergmann had the honor of revising the latest edition in 2020. You can get the latest edition of Review of Vacuum for Service Engineers from TruTech Tools HERE.

Pulling a Schrader core before evacuation makes a big difference in the speed of the evacuation. You can use a core remover tool to pull the cores when the system is NOT pressurized.

There are three common types of ports to access the system: the Schrader core, high-flow core (CoreMax), and the multi-position service valve. You can mid-seat the multi-position service valve for high flow, but you need to remove or depress cores on the other two port types. (You must use a special CoreMax CRT to remove high-flow cores.)

Three factors limit the speed of evacuation: the conductance speed of the pump, of the connecting hoses, and of the system. The hoses and manifold can severely impact evacuation. TXV and piston metering devices have short orifices and have very little impact on the evacuation time; on TXVs and EXVs, the valve should be fully open.

When pulling a vacuum, make sure the vacuum pump works properly and has clean oil. Once you know that the pump is working, only pull on a tight system (no leaks) and make sure the seals are in good shape.

Bryan also discusses:

Micron gauge and hose placement
Core depressors and CRTs
Refrigerant holding charge
When core restrictions are helpful
Single-hose vs. two-hose evacuation speed
Moisture removal
One-hose evacuation of a split air conditioner
Decay testing
Hard shut-off valves
How to solve micron gauge issues
Nitrogen sweeps for wet systems

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Check out our handy calculators HERE.

Check out information on the 2022 HVACR Training Symposium at https://hvacrschool.com/symposium/.

Electric Heat - Short 128 Oct 12, 2021

Show notes

In today's short podcast, Bryan discusses electric heat, how we use it in our work, and what it does.

Also called heat strips or heat elements, electric heat is a supplemental heat source that we usually see on heat pumps. We generally see them in fan coils within a cartridge or a kit at the top of an air handler. However, not all systems have backup heat.

We want to avoid running electric heat as much as possible because it is inefficient. There is almost nothing we can do to make heat strips more efficient; they will usually yield around 3.41 BTUs per watt.

We usually only run heat elements when a heating system can't keep up with the heat loss. However, the electric heat often runs more often than it should, which can cause inefficient conditions. You can avoid inefficient conditions by programming the thermostat properly.

If you reduce the voltage on the heat strips, the less heat they will produce. Current ratings also differ between 208v or 240v applications. When you have more voltage, you'll have more current as well.

In some municipalities, you may have to use a thermostat that keeps heat strips OFF unless the temperature is below a certain value, often 40 degrees. Your electric heat should also be the last resort for a system.

Heat strips also help with heating when a heat pump is in defrost. The defrost board backfeeds the electric heat. These heat strips are also often designed with an interlock that forces the blower on whenever the electric heat is on (but not the other way around).

Bryan also discusses:

Kilowatts and electrical ratings
Wiring and relays
Wire sizing
Furnace-to-heat-pump conversions
Possible hazards

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Check out our handy calculators HERE.Check out information on the 2022 HVACR Training Symposium at https://hvacrschool.com/symposium/.

Introducing Refrigeration Mentor w/ Trevor Oct 07, 2021

Show notes

Trevor Matthews comes on the podcast to discuss his newest project, Refrigeration Mentor. Refrigeration Mentor uses Trevor's experience as a trainer and field technician to guide others in their careers.

Trevor's goal is to help commercial refrigeration technicians grow and become more confident in their skills. He wants them to become the best technician they can be, and he believes that mentorship is one of the things that make our industry great. Mentorship can help people advance their careers, sharpen their skills, and ease their anxiety about work.

When we share knowledge, we bring value to the technicians. That value extends to the customer when technicians are more confident in their work and do better jobs. A good mentor has a commitment to doing quality work within the trade but will make their mentees feel comfortable to admit what they don't know.

Mentors can also help their mentees develop a solid work-life balance that helps mentees be present to their jobs and their families. The mentor's job is to help their mentees reach their goals, whether that's learning a new skill, entering a leadership role, or even starting a business.

Trevor also wants to help business owners or managers strengthen their teams. He believes that a dynamic culture and a strong emphasis on training will help a business (and the industry as a whole) grow. His mentorship approach comes from strengthening technicians, businesses, and the industry from the heart.

Trevor and Bryan also discuss:

Holistic training
Hesitancy to admit what we don't know
Passionate teachers
Mental health
Starting and managing a business from the inside
Investing in training and mentorship

Check out Trevor's website at https://refrigerationmentor.com/.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Check out our handy calculators HERE.

Check out information on the 2022 HVACR Training Symposium at https://hvacrschool.com/sympos

Effective IAQ Measurement & Control w/ Haven Oct 05, 2021

Show notes

In this podcast, Ben from HAVEN IAQ, Kaleb, and Bryan discuss how to control indoor air quality and take effective, meaningful, accurate measurements.

HAVEN is a platform that offers hardware and software delivered to a homeowner through an HVAC professional. HAVEN's goal is to give its customers a healthier, more comfortable home using IAQ solutions.

The hardware (controls, etc.) works with the HAVEN software to give customers and contractors data about IAQ and the performance of the HVAC equipment. Right now, you may install up to two HAVEN controllers and one monitor per zone to help control equipment and monitor the air content.

Air sampling occurs every hour, whether the HVAC system is running or not. Customers can learn to control their ventilation habits to address acute events (e.g., a spike in humidity from cooking), which only result in short-term IAQ problems. However, contractors can use the air sampling data to develop solutions for chronic events (e.g., constant high humidity).

Solutions, even simple filtration ones, are best left to the contractors to figure out. The integration of most IAQ products requires some degree of design and planning. HAVEN products do NOT provide plug-and-play solutions. While "demand" solutions can introduce outdoor air to prevent a viral problem, you could introduce a moisture problem without proper planning.

Ben, Kaleb, and Bryan also discuss:

HAVEN central air controller
Building relationships with customers
Software integrations with other platforms
Filtration caveats
HAVEN Pro Portal and Personal Use Program
Ease of connecting HAVEN controllers to equipment
"Demand" ventilation, dehumidification, etc.
Importance of airflow
Making IAQ product sales and educating homeowners
IAQ placebos
In-duct monitoring
Introducing HAVEN products to your market

Please visit pro.haveniaq.com to access HAVEN's Pro Portal.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Check out our handy calculators HERE.

Check out information on the 2022 HVACR Training Symposium at https://hvacrschool.com/symposium/.

College vs. Skilled Trades w/ Ryan Gorman Sep 30, 2021

Show notes

Ryan Gorman comes on the podcast to discuss the differences between a college education and early career opportunities in the skilled trades.

Many parents feel pressured to send their children to college and encourage them to get a four-year degree. Despite what society may lead us to believe, there is no shame in thinking that college may not be suitable for you or your child; the skilled trades have many opportunities for people to learn throughout their lives and make a good living.

In many cases, parents may see college as a ticket to the starting line. Unfortunately, college tuition has skyrocketed over the years, and a good ROI is not guaranteed. Instead, a career in the skilled trades can allow a person to develop hard skills and land a well-paying job at a young age. As the skills gap widens, young people who learn skills make themselves attractive to employers and increase their earning potential.

Children and teenagers who want to become engineers may actually prefer a trades career where they get to work with their hands. The path to the trades is less expensive than getting a four-year degree and may prove more fulfilling in the long run. Internships, small businesses, and trades careers are viable paths for young people; we don't present these possibilities at a young age, but they are worth considering for people who may not benefit from college.

Ryan and Bryan also discuss: