HVAC School - For Techs, By Techs

Latest Episodes:

Value Design in High Performance Home HVAC w/ Comfort Squad May 05, 2022

Show notes

Neil Comparetto and John Semmelhack of the Comfort Squad join Bryan to discuss high-quality value design in a high-performance home. They explain how they design HVAC systems (heat pumps) for low-load homes in ways that are affordable, efficient, and comfortable.

High-performance, low-load homes need to be energy-efficient AND comfortable, and it can be a challenge to get both. Manual J calculations aren't as common as they probably should be, and it can be difficult to get accurate data about air leakage, power consumption, and radiant gains as well. So, John and Neil try to collect their own data and do aggressive load calculations to avoid the fudge factors that are all too common. The air velocity inside the ducts tends to be lower in these sorts of systems.

When you have relatively low airflow in the ductwork of high-performance homes, you don't need as many ducts or for the ductwork to be particularly large. With minimalistic ductwork, supply register placement, face velocity, and throw become very important, especially because those factors are responsible for air mixing. When the duct design conditions are right and the load has been matched, you typically get long runtimes and good air mixing.

In many cases, John and Neil use variable-speed motors in their outdoor units that allow for high heating performance. The capacity ranges are wide, allowing the units to run even during exceptionally low-load conditions. They also use flex ducts due to their pre-insulation, noise suppression, and inexpensiveness; they just try to keep it sealed and avoid compressing the ductwork.

Neil, John, and Bryan also discuss:

Monitoring load conditions with software
Design considerations for filter grilles and central returns
Room pressurization and airflow testing
Transfer grilles
The Coanda effect and curved-blade registers
Vent sizing
Flex duct installation best practices
Duct fittings
ERVs

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.

Putting Contractor Success First w/ METUS Apr 28, 2022

Show notes

Lacey Dietz with METUS and Scott Arnold with Rycor HVAC join the podcast to talk about how the industry can start putting contractor success first. They talk about Mitsubishi Electric (METUS)'s commitment to contractor success and what that looks like.

METUS's contractor program aims to provide training, support, and recognition to create a community of successful contractors. Support comes in the form of marketing, training, tech support, and customer service, and those services are available to contractors who sell and represent Mitsubishi's products.

As a contractor who works with Mitsubishi, Scott has been able to specialize the labor in his business and grow his business as one that specializes in installing Mitsubishi systems. Mitsubishi also provided top-quality training and allowed Scott to streamline his training process and get his apprentices feeling confident and ready to go into the field quickly.

Adoption rates for Mitsubishi's ductless technology have increased over the past couple of years, especially as people have spent more time in their homes and started re-thinking indoor comfort. Those who are educated about heat pumps also tend to appreciate the technology as well as the mini-split units' small footprints in their homes. The mini-split units' smaller environmental impact than unitary systems is also a plus.

Lacey, Scott, and Bryan also discuss:

Scott's work with heat pumps in New York
Programs that benefit contractors
Mitsubishi's products and supply chain management
Diamond Contractor program and tiered contractors
Mitsubishi's lead generation program and referrals
Ductless vs. unitary systems
Bringing education into sales
Dealing with business growth in a challenging labor market
Overcoming objections

Learn more about Mitsubishi and its products, visit https://www.mitsubishicomfort.com/, and you can learn how to become a contractor at https://discover.mitsubishicomfort.com/contractors.

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.

Retrotec - IBS 2022 Apr 26, 2022

Show notes

Sam Myers with Retrotec talks to Bryan about pressures in the home and why they matter for HVAC solutions at IBS 2022.

Technicians focus a lot on ductwork and airflow, but many of them don't focus on how the building envelope impacts HVAC performance. A lot of the HVAC equipment's performance is affected by the push and pull of air caused by leaky areas in the building envelope.

If you have a room with too much air and another room with too little, you will have unbalanced pressures. Unbalanced pressures may result in discomfort and latent load issues, especially when unconditioned air is pulled in through the attic. Sealing the envelope well and using dampers as necessary can minimize the comfort issues caused by pressure imbalances in the home.

Instead of just using manometers for static and gas pressure, we can also use high-resolution manometers under doors to pick up pressure differences. However, the manometer MUST be high-res to pick up those subtle (but palpable) differences in pressure. A blower door is also a great tool, especially when you use it with a thermal imaging camera; the blower door amplifies the temperature effects that a thermal camera will detect, especially if you also have a good delta T.

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.

Birmingham training class Apr 21, 2022

Show notes

This podcast is a class that Bryan taught for BTrained in Birmingham, AL. He covers troubleshooting, installation, and commissioning best practices with a focus on the fundamentals.

To be a good troubleshooter, you must be able to find the problem, identify the source of the problem, fix the problem, and optimize performance based on your data, the customer's comments, and your observations. The Five Pillars of diagnosis aren't comprehensive diagnostic or charging criteria, but they can help you charge or diagnose a system.

Isolation diagnosis works best for electrical components; you isolate the problem area from the system and see how the system works without the suspected issue. If the system operates normally without the component in question, then we can conclude that our hypothesis about the "problem" part was correct.

Wide-narrow-wide troubleshooting is an approach that allows you to inspect the entire system, zero in on the problem, and optimize the entire system. By starting wide, going narrow, and going wide again, you can troubleshoot holistically.

Installations take place in several phases: pre-planning, planning, demo, installation, and commissioning. Many people place a lot of emphasis on the demo and installation and neglect the conversations and procedures associated with pre-planning, planning, and commissioning.

Bryan also covers:

Heuristics and mental shortcuts
Evaporation vs. boiling
Rules of thumb
Head pressure, suction pressure, and compression ratio
Energy transfer fundamentals
What superheat and subcooling really indicate
Restrictions and temperature drop
Delta T
"Redneck" compressor test
Testing circuits
Useful measurements and test instrumentation
Causes of compressor failure
Measuring airflow
Low vs. high static pressure
Bringing tribal knowledge to building design
Ductless systems, ventilating dehumidification, and sensible heat ratio
Manual J, attics, and combustion air
Radiant barriers and heat transfer
Supply relative humidity
Dehumidifier configuration and system design
Bad envelopes
Vented attics
Duct upgrades
Total effective length and turning vanes
Evacuation

Learn more about BTrained at https://btrained.net/ or on the BTrained YouTube channel at https://www.youtube.com/channel/UCnlDsWHT68gVwPrYYO5vhrw.

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.

Ross Trethewey IBS 2022 - Short #141 Apr 19, 2022

Show notes

Bryan has a bit of an industry nerd out with Ross Trethewey from "This Old House" and TE2 Engineering at IBS 2022 (the International Builders' Show). Ross's education and career have focused on mechanical engineering, especially with sustainable solutions.

In building science, the key mindset is to think of the building as a system. Using that school of thought, Ross has developed building science and HVAC solutions that also consider indoor air quality and ventilation, such as hybrid VRF systems.

Many of Ross's solutions take the best aspects of air-source and ground-source heat pumps and apply those to hydronics. Some exciting applications for those types of systems could include simultaneous heating and cooling as well as the integration of domestic hot water.

Demand control ventilation has been used for a long time in the commercial world, but its possible use in residential applications is another exciting thing to consider. With proper control devices, DCV would give us the opportunity to control temperature, humidity, VOCs, carbon monoxide, carbon dioxide, and radon. In residential applications, DCV has to be a delicate balancing act, as bringing in too much outdoor air would require us to condition that air. High latent loads also present challenges to some of the ventilation solutions in development.

Serviceability is another challenge to DCV usage in residential applications; whenever an innovative system is brought to the market, very few people will know how to fix and maintain those systems. One of the possible solutions is to create instruction manuals and give education similar to what already exists for package units. 3D models and animations also help make complicated systems easier to understand.

Ross's presence on "This Old House" marks the third generation of Tretheweys on the show. Ross is excited to talk about building science and HVAC innovations and concepts while on the show.

Heat pumps are also getting better, especially due to inverter-driven compressors, enhanced vapor injection, advanced control systems, and ECMs. Heat pumps are safer than gas-fired equipment, and we have made them work well in subzero temperatures (because we're nowhere near absolute zero).

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.

Replacing a Compressor - Step by Step Apr 14, 2022

Show notes

In this podcast, Bryan goes through the entire process of replacing a compressor step-by-step. This process is what the Kalos team uses to replace a failed compressor and make sure it doesn't fail again.

Before replacing a compressor, you must figure out how the compressor failed; grounded conditions often lead to acid, so it's a good idea to test for acid and see if you need to address a burnout. In any case, make sure you have the correct tools for the job (including a compatible replacement compressor).

When you arrive at the job site, be sure to confirm the diagnosis and check to see if the unit has a hard start kit. That's also the time to do a visual inspection, checking airflow as well as the filter, blower, and coil cleanliness. Recover and weigh out the refrigerant charge.

Unscrew the foot bolts and lift the old compressor out. Then, seal the compressor once it's out. If you're dealing with burnout, clean out or replace the accumulator (you will install/reinstall it shortly). Cut out and replace the existing liquid line drier and install a suction drier in a place where it can be easily removed.

When piping in the new compressor, make sure you protect heat-sensitive parts and do a quality brazing job. Install the new capacitor and hard start kit, too, keeping wiring away from places where it may chafe.

Test for leaks, evacuate the system, charge the system, and check your five pillars as well as voltage. Finish by cleaning the drain and double-checking airflow.

Bryan also covers:

Misdiagnosed compressor failure
Parts needed for replacing a compressor
What makes a compatible replacement compressor?
Billing and pricing
Alloys and fluxes
Replacing TXVs, capacitors, contactors, and reversing valves
Cutting vs. unsweating
Suction driers and pressure drop
Charging considerations

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.

Refrigerant Top off, Drop in and Retrofit - Short #140 Apr 12, 2022

Show notes

In this short podcast, Bryan explains what it means to top off, drop in, and retrofit refrigerants. He describes the differences between those three things to dispel some of the confusion they may cause.

Topping off a system means that you add refrigerant to a low existing charge to get it back up to a normal level. In some cases, people top off systems with dissimilar refrigerants (e.g., topping off R-22 systems with cheaper R-407C). Topping off a system with a dissimilar refrigerant is unacceptable, as it's against EPA guidelines and leaves you with an undefined refrigerant mixture. You're only supposed to top off a system with the same refrigerant that's already in it.

High-glide refrigerant blends can be tricky to top off when there is a leak, as one refrigerant type may leak more quickly than the other and leave you with a different chemical profile. So, you're better off recovering and starting over when you have lost a significant amount of charge to a leak.

If you want to recharge an entire system by recovering the existing charge, you would instead be using a "drop-in" refrigerant. There are no drop-in solutions for R-410A systems. However, some commercial equipment manufacturers can offer information about drop-in solutions, though they are relatively rare, especially as oil has changed over the years. When you drop in refrigerant, you don't have to change O-rings, Schrader cores, or other components. Drop-ins are NOT necessarily like-for-like when it comes to charging.

"Retrofit" is a relatively broad term that refers to any type of refrigerant change. The retrofitting practices that may have worked for A1 CFC systems to A1 HCFC systems will NOT work for A1 to A2L refrigerants. We need new installations for flammable refrigerant 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.

The Value of Networking for Techs w/ Trevor Apr 07, 2022

Show notes

Trevor Matthews, the founder of Refrigeration Mentor, is back on the podcast. This time, he and Bryan talk about the value of networking for HVAC techs as the conference season comes to a close.

Many trade events are networking opportunities that allow you to build relationships with other tradespeople, educators, mentors, and even other companies. You can also learn many trade and business tools that help you as a technician. Many technical and business conversations occur at trade events, and there is a lot to learn from those, whether you're directly involved or just listening. It can also be useful to sit in on classes or presentations about topics that you don't directly deal with, such as building science.

Networking also has value for technicians because it can provide several means of personal development. Making connections with potential mentors can open the doors to new career opportunities, even in places where you wouldn't have expected yourself to work.

If you see someone you want to talk to at an event, feel free to go up and talk to them. Trade events are places where people expect to get to know one another, so many of the people who attend them genuinely want to talk to others in the trade. People like Trevor are happy to share their knowledge and help you develop yourself as a technician. You can also send people emails introducing yourself to them before the event if you're a bit introverted and uncomfortable putting yourself out there.

Trevor and Bryan also discuss:

Being isolated in a "bubble"
Choosing to work or visit conferences
Networking to avoid getting stuck
Planning trips around trade conferences
The 2023 HVACR Training Symposium
Specialized conferences
Refrigeration Mentor

Learn more about Trevor's work 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.

How to EFFECTIVELY implement educational growth w/ David Richardson Mar 24, 2022

Show notes

David Richardson of NCI joins the HVAC School podcast to talk about how we can implement educational growth effectively throughout the trade. NCI started as a premium training resource about airflow testing, but the organization eventually started teaching about combustion testing as well.

When we improve the industry, we need to be able to have concrete ways to see what we've been doing wrong or what we can do better. Test instruments allow us to see the whats and whys behind what we do. Education needs to be focused on bringing those test instruments into training AND teaching others how to use them properly.

Once we find a way to understand the invisible aspects of what we do, we can get into systems thinking and grasp the more abstract concepts much more easily. When people are introduced to concepts in a logical sequence, they can build their knowledge on what affects the system and why it does do.

When we tie everything together, including using solid data, testing in and testing out, and using sources to help you interpret data, we can implement educational growth more effectively. Most of all, we can learn how to translate the technical into practical, which helps us communicate with the customers in ways that matter.

However, the most important thing about test instrumentation and applying it to learning is understanding why you are doing those tests or why you want to do them.

David and Bryan also discuss:

The purpose of traverse tests
The mechanics of NCI's teaching (PATH to performance)
To charge or not to charge for combustion analysis
What NCI does and how to get involved with NCI

Learn more about NCI or get involved with their training at https://nationalcomfortinstitute.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.

Comfort Investigation on TV w/ Corbett Lunsford Mar 20, 2022

Show notes

Corbett Lunsford of Home Diagnosis joins Kaleb to record a podcast about comfort investigation on TV. The two of them discuss how comfort investigation works on TV shows, what Home Diagnosis hopes to accomplish, and some building performance tips.

Home Diagnosis is mostly aimed at homeowners, but HVAC technicians would also benefit from the show, as it dives into science and testing. The show promotes consumer education and contractor accountability.

Diagnostics and testing are absolute MUSTS for providing the best possible solutions and transforming your business. You put yourself in another league when you take measurements and have the data to create tailored solutions. In other words, you can't manage what you can't measure, and if you're not testing, you're guessing.

The current paradigm shift in the industry has to do with custom designs. Physics, chemistry, and microbiology are all important facets of applied science to consider when coming up with a custom solution. Many buildings have distinct microbiological profiles, including bakeries with yeast or cheese production or aging facilities. Natural events and human activity can change these buildings' microbiological profiles.

Ventilation is part of the equation of home performance, and it's a pretty delicate one that HVAC techs can control. When it comes to ventilation, we would be wise to avoid selling products we don't understand. Ventilation solutions may also be appropriate for one structure but inappropriate for another, so we need to think about the applications of these solutions.

Corbett and Kaleb also discuss: