HVAC School - For Techs, By Techs

In today’s short podcast, Bryan discusses the key factors for system performance WITHOUT doing a deep dive into system commissioning. “Performance” refers to system efficiency, capacity, air filtration/cleanliness, longevity, and the ability to match the latent and sensible loads of a space. System airflow is the main performance factor to consider. To determine proper airflow (CFM), consult Manuals S, J, and D to perform calculations. In general, the absolute lowest limit is around 275 CFM (in extreme dehumidification mode), and the highest limit should be around 525 CFM (in arid climates or at altitude). You can determine your CFM target after you set up your ECM motor in the design. Then, you can also check airflow indicators: total external static pressure and pressure drop across the filter. The best way to improve airflow is to reduce pressure drop across the filter and build a better return plenum. For improving overall system performance, make sure the ducts are appropriately sized. System charge is another important performance factor. There is a lot more to evaluating charge than checking the superheat and subcooling. If possible, it is a good idea to weigh the charge with a scale and see how it matches up with the line length. In terms of long-term performance, the condenser’s location and cleanliness are also vital. Overall, a condenser works best if you put it in a slightly shaded area or on the north/east side of a building. The outdoor unit should also have some clearance from bushes and walls. Make sure the condenser is positioned away from pool equipment, water softener discharge, and dryer vent discharge. The goal is to keep the outdoor unit corrosion-free and able to “breathe.”   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.

In today’s podcast, Trevor and Bryan discuss Copeland Scroll Compressor Multiples for Air Conditioning. “Multiples” refer to equipment setups with multiple compressors that have connected suction and discharge lines, so they resemble parallel rack refrigeration setups. Multiples typically come in tandem (2) or trio (3) sets. Compared to having a single giant compressor, multiples are more efficient, more reliable, and have the ability to keep running in case if there’s a compressor failure. As a result, we often use multiples in rooftop units, makeup air units, and chillers. When you’re working on multiples or troubleshooting multiples, it’s okay to have sight glasses that indicate different oil levels. If you shut the compressors down and restart them, they should equalize. If you have a single compressor failure on a set of multiples, then you may have to replace both compressors in a tandem set; the manufacturer does not make single replacements for some tandem models. So, you can check the Application Engineering (AE) bulletin to determine your replacement needs. Multiples may contain compressors of different sizes. Compressors of different sizes have different mass flow rates. In these cases, you would use a flow restrictor to balance the mass flow across the compressors. On the refrigerant management end, the Copeland Scroll multiples will generally benefit from a crankcase heater. Correct location and installation of the crankcase heater are critical for proper functioning in multiples, and you can find that information in the manufacturer literature. Sometimes, you may also need an accumulator if there is a risk of refrigerant migration. Bryan and Trevor also discuss: Individual vs. multiple compressor manuals Oil equalization lines Compressor clamping Variable speed motors and compressor variability Sweating and flow restrictors Maximum tilt Adding oil Torque values   Check out the AE-1430 bulletin HERE. Check out Emerson’s HVACR training HERE. Then, navigate to “Contractor Tool Box Talks with Emerson.” 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.

In today’s short podcast, Bryan clears up the differences between markup and profit margins in HVAC businesses. The number one mistake that people make in business is confusing markup and gross margin. For example, you can double the price of a $50-part and sell it for $100. That would be a 100% markup. However, your gross margin is NOT 100%; your gross margin is only 50%; you only made a 50% profit on the total sale.  In the same case you have above, you have a 50% cost of goods sold (COGS). COGS is the direct cost of the expenses you paid to sell your service or product. The opposite of COGS is overhead. Overhead includes anything that doesn’t directly bring money to your business (rent, utility bills, etc.). Let’s say that your overhead costs total $30. You only end up with $20 of net profit. Typically, 10-20% net profit is a good (if slightly idealistic) goal. Net profit can contribute to business growth if you put it into your business. For example, you can use that money for advertising, buying vans, and buying better tools. If you want to determine a 10-20% goal, DO NOT USE MARKUP. Instead, you need to divide by your COGS expenses. In the case of the $50-scenario, let’s say that our cost of goods sold is 60%, so that seems like a 40% markup. You would divide 50 by 0.6, and you would get $83.33. If you multiplied by markup (140% or 1.4), you would have gotten $70. You wouldn’t come close to your gross margin number using the markup method.    Learn more about Refrigeration Technologies HERE. Check out NAVAC HERE. Check out SpeedClean 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.

In today’s podcast, Eric Mele and Bryan explain the planning, layout, and execution of HVAC projects. They mostly cover commercial ductwork but also touch on piping and some residential projects. Planning The first step is to review the construction plan WITH a site visit. It is best to see how a plan works within the space; plans may be feasible on paper but may not work out as planned in the actual space.  During the site visit, you also want to establish solid communication with everyone else on the project. As such, it is best practice to have a coordination meeting with the general contractor and other trades (such as drywallers) to communicate potential areas of conflict. (When building ducts in commercial structures, you will want to watch out for conflicts with trusses, joists, fire sprinklers, and plumbing/drains. In residential structures, you will have to watch out for ventilation paths, such as dryer vents and kitchen exhaust vents.)  Before deciding to alter the design, be sure to communicate any possible alterations to the GC and other trades.  Layout If possible, the next step is to lay out your construction plans on the floor. Constantly referring back to paper or digital plans is not productive. You can usually chalk up or spray paint the concrete at a construction site to draw your layout and plan the construction accurately within the space. The floor is also likely to be your best reference. You can also use string to plot the locations where the hangers would go, especially if you have long runs of ductwork. Execution The first step of executing a project is preparing for hanging. When preparing for hanging, it is best to perform as much of the work on the floor as possible. The duct board can be stapled, taped, or masticed on the floor. Then, the hangers go up. If you have multiple people working on a project, one person can assemble the ducts on the floor and wait for the mastic to dry while another person puts up hangers. You can usually wrap the ducts on the floor, and it is usually easier to do so. However, it is best to check with your GC before you do it. You may need the ductwork to pass an inspection. When it comes to fasteners, you can use screws, flat strapping, or even aircraft cable. If using screws as fasteners, try to make sure that all of the screws have the same heads. Having to switch out drillbits for all the different screws is very inefficient. (As always, make sure your tools are easy to reach and in locations that won’t hurt your back. It is a good idea to have a toolbelt or workstation.) When working with flex duct, make the takeoffs as easy for yourself as possible. You can use mastic as a seal for the collar instead of tape, as it may be easier to seal. (Either way, watch out for leaks.) No matter what you do, make sure you’re taking care of your body, doing as much work on the floor as possible, and adhering to all applicable building codes. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In today’s short podcast, Bryan explores the differences between startup and commissioning. Startups typically involve going in during the construction phase after the drywall has been sealed up. (Vents, ducts, and copper piping typically go in before the drywall.) A technician can then perform a startup. The startup includes testing the drain line, checking the charge, checking for leaks, and seeing if the equipment performs its most basic function. (Does the gas furnace make flame? Does the A/C unit blow cold air?)  The startup’s goal is to get the equipment working. A startup does NOT focus on peak performance. A good startup will typically suffice for a cookie-cutter residential construction.  Conversely, the goal of commissioning is to optimize the equipment and test the advanced functions. Combustion analysis, airflow tests, and dehumidification tests all fall under the “commissioning” umbrella. Commissioning is where we use Manual S and Manual J to see if the equipment is appropriate for the home. Data collection, especially on sensible and latent capacities, is the core element of commissioning.  Commissioning also involves checking up on secondary functions, such as checking if heat strips activate during defrost. A custom construction plan will require commissioning to ensure that the equipment runs optimally in the uniquely designed space. So, in short, equipment startup is about making sure the equipment works as it should on a basic level. On the other hand, commissioning uses data and specific instrumentation to make sure the equipment is running to its design and full potential. Bryan also covers: Stages of residential construction Startup in new construction projects Capping and filling drains Who can perform a startup? (Junior techs, installers, senior techs, etc.) Instrumentation for commissioning If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In today’s podcast, Eric Kaiser and Bryan talk about mentorship in the HVAC industry. They discuss what it means to be a good mentor, how to find a good mentor, and what it means to be mentored.  Mentorship is an organic process. Most mentees don’t go up to someone they respect and formally ask that person to be their mentor. Respect is the foundation of the mentor-mentee relationship; formal mentorship often resembles friendship in many ways.  However, mentorship can take more forms than the traditional mentor-mentee relationship. In the digital age, podcasts and YouTube channels that readily share information about a skill are resources that can fulfill the same role as a traditional mentor. A good mentor has a willingness to explain the how and why behind a question or process; they don’t give simple answers. Good mentors must also be able to provide resources for their mentees; they know the limits of their knowledge and are willing to find those answers with their mentees. Often, the better mentors are humble and don’t flaunt their experience. Good mentors want to see their mentees do well and grow; they don’t want their mentees to follow and copy them. The support in the relationship goes both ways. The mentee must want to support their mentor, not compete with them. Mentees must be willing to start conversations and ask for clarification; an ineffective mentee waits for answers to be spoonfed to them. Good mentees are also willing to challenge their mentors at times [respectfully]; they don’t excessively flatter their mentors. Bryan and Eric also cover: Personal growth Online mentorship resources Cultish mentors Outgrowing and leaving mentors “Stealing” in mentor relationships Unproductive mentorship Honoring mentorship If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In today’s podcast, Bryan explores the upsides of choosing a career in the skilled trades instead of going to college. He also covers ways to prepare your child for a trades education and career while they are still deciding what to do with their lives. When we think about what we want for our kids, the following goals come up quite often: purpose, financial upside and reward, freedom from debt, and joy. The trades can offer a lifestyle that covers all of these bases. However, the opinions of our friends and the fear of failing as a parent may prevent us from encouraging our children to enter the trades.  Going to college has plenty of downsides, such as saddling students with debt and not guaranteeing opportunities to move forward in a career. Alternative career paths include the HVAC/R trades, electricians, off-grid solar technicians, and so on. Your child will learn hard skills on these career paths that are easily transferable. These trades also generally have plenty of apprenticeship opportunities. In the case of HVAC/R, technicians may also have the opportunity to earn a lot more money in only a few years. At that rate, they will have ideally saved some money to go to college later on if they believe that college is truly the right choice for them. Bryan also covers: The desire for purpose and impact in a career Doing good work vs. being seen doing good work Advantages and disadvantages of college The societal obsession with certificates of completion How to avoid feeling “stuck” as a young adult What it means to have a high opportunity/learning ceiling Interesting and meaningful problem-solving in a career Acquiring hard skills Diversity of challenges in a career Strong lateral problem-solving skills Advantages and disadvantages of home education Autodidactism Alternative career paths with financial and personal upside If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In today’s short podcast, Bryan explores triple evacuation. Many people believe that we don’t like triple evac, but that’s simply NOT true. We’re here to set the record straight. If the manufacturer tells you to follow triple evacuation processes, then it’s a good idea to do what they say. We won’t argue with that. However, our argument is that the procedure can be more time-consuming than it’s worth when it’s NOT necessary. Deep vacuum technically counts as a vacuum pulled below 500 microns (in residential, that target is usually 200-300 microns). Most modern micron gauges and tools make it easy to achieve a deep vacuum. In a triple evacuation, you pull the vacuum three times (instead of once). Between pulling vacuums, you break with nitrogen before pulling the vacuum back down. Triple evacuation originated in a time when micron gauges and vacuum pumps were less reliable. We did not take deep vacuum very seriously, especially since mineral oil (MO) typically did not break down inside the system. (Modern oils like polyolester/POE break down rather easily, so pulling a deep vacuum is much more vital nowadays.) Instead of merely breaking with nitrogen, Bryan recommends flowing it. It’s best to flow the nitrogen with force to move the oil around more effectively. In turn, your vacuum will pull down more quickly and efficiently. So, triple evacuation isn’t bad, but it can be time-consuming. Just be sure to follow all best practices if you perform a triple evacuation. Join us as we cover: Deep vacuum targets Micron targets Breaking with nitrogen Flowing nitrogen POE vs. mineral oil Old manufacturer literature about deep vacuum Microns   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.

In today’s podcast, Bryan explains how he teaches physics. He believes that teaching physics is about continuously building a mental model, and he covers the methods and mindsets that facilitate that learning style.  The basic Wikipedia definition of physics states that it is a science that deals with matter, energy, and their interactions. Even then, we can simplify “matter” to “stuff.” Simplifications like these help students feel more familiar with the subject and NOT feel intimidated by the material. Students learn best when they feel like they can grasp the topics out of the gate. That is why the math-based approaches of traditional education might turn students away from physics. Some students who don’t like math might feel out of their depth when teachers approach topics with a mathematical approach.  Instead, effective teaching is about attaching experiences to a concept. Teachers can take stock of what students already know and build on that. They can also attach experiences to a concept, such as by allowing students to have hands-on experiences with physics examples in the real world. Once students have relevant experiences, they have the tools to learn through similes and analogies. Bryan covers: Socratic learning Comparing levers to seesaws for educational purposes Experimentation and experience Similes, metaphors, and analogies Shortcomings of math-based learning methods Creating “cartoons” in your head to learn topics Teaching superheat and subcool with mental “cartoons” States of matter Humidity and the weight of water vapor Electron movement Steam and why it’s complicated Teaching electricity with comparisons (water, drawbridges, jump ropes) How children (and babies) learn about physics as they navigate the world Mythbusting Remember, when it comes to education, the goal is to learn, NOT to impress people. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In today’s short podcast, Bryan explores the dangers of cold tanks during refrigerant recovery. Whenever you have a recovery tank, you only want to fill it to 80% capacity in the liquid state. The same goes for all sorts of vessels (coils, etc.).  However, capacity isn’t the only factor to consider for safety. We need to know what our maximum temperature will be. You will be in greater danger of overfilling a tank when it is cold because higher temperatures increase the pressure. High pressure in a closed space may lead to explosions. When you fill a tank to 80% under cold conditions, normal temperature conditions could put you in the danger zone (let alone temperatures above 100°F). So, it’s better to determine your tank fill based on densities at the MAXIMUM temperatures you will encounter, NOT for the measurements at artificial cooling conditions (such as when you put the tank in ice water during recovery). In the end, just be careful when you’re recovering into a cold tank or using tanks when it’s cold outside. That will help you avoid hydrostatic pressure buildup and explosions. Bryan covers: The 80% capacity rule for filling vessels with liquid Why the 80% capacity rule varies by temperature Temperature, pressure, and density Hydrostatic pressure AHRI’s 77°F guideline Ice buckets for recovery What to do if a tank vents its refrigerant on you while driving If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.