HVAC School - For Techs, By Techs

Latest Episodes:

How to Measure Total System Airflow w/ Steven Aug 05, 2021

Show notes

In today's podcast, Steven Rogers joins Bryan to talk about measuring total system airflow.

Fluid measurement is NOT restricted to liquids; a fluid is anything that flows, including liquids and gases. In HVAC, we deal with both of them, but airflow is strictly limited to the flow of gas. The airflow we experience in HVAC is exclusively turbulent flow, NOT truly laminar flow.

Total system airflow is difficult to measure directly; we can use flow hoods, but they have their limitations, especially on systems that have multiple returns. So, we measure pressures that give us clues about the airflow tendencies.

One of the most recognizable measurements is static pressure. Many factors can contribute to poor static pressure, including dirty filters and poorly designed supply and return plenums.

All measurements that you use to calculate static pressure will require an average. You take readings at multiple points of the duct, so you need to calculate an average value, whether you're using static pressure tips, a hot wire anemometer, or a vane anemometer. Measurements are also particularly difficult to take in the supply registers, as there are almost no runs of straight duct.

Recently, the TrueFlow grid has come on the scene to make airflow measurement easier. The grid relies on torque and RPM data to determine the total system airflow. The TrueFlow grid slides in where the filter goes and measures the total system airflow. The grid works with an app that considers the system tonnage to let you know how good or bad the airflow is.

Bryan and Steven also discuss:

Bernoulli's principle
"Moving" CFM targets
Flow hood limitations
Laminar vs. turbulent flow
Static pressure probes vs. pitot tubes
TESP and fan charts
Precision vs. typical manometer
TrueFlow grid vs. filter restriction
Water heater backdraft
Depressurization and combustion air zone

Check out The Energy Conservatory's Website HERE. You can also check out the TrueFlow grid on that site or at HERE.

Check out our handy calculators HERE.

HVAC/R Career Advancement - Short 125 Aug 03, 2021

Show notes

In today's short podcast, Bryan explains how growth happens in an HVAC/R career. He also gives tips to get "unstuck" if you feel like you aren't moving forward.

You won't move forward if you haven't set a goal to move forward. Making a "vision board" helps you determine what matters in your life, and it helps you clarify what you'll need to do in order to achieve your life goals. That way, you can use your career to help achieve those goals and see whose support you need.

Having a growth mindset and a lifelong learning mindset is essential for success. The growth mindset will help you deal with the "growing pains" of advancement (such as occasional failures). People with positive attitudes also tend to see more possibilities for their future careers. On the other hand, negative people are likely to idle in their careers.

You also want to surround yourself with people who will bring out your best. It's great to be around people who challenge you, have positive outlooks, and are happy for you when you make progress. Moreover, you want to be the person who is authentically excited when other people succeed and do good work. Also, try not to burn bridges with others.

To advance in your HVAC career specifically, develop your hands-on skills. Think about it this way: are you merely doing your job's requirements, or are you working on yourself? Read through manuals and check out technical materials to become more literate with systems and do better work on them. Also, try to find a mentor who will help you grow. People skills are underrated in our industry but are critical for career advancement.

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

Mini-Split Controls Strategy w/ METUS Jul 29, 2021

Show notes

In today's podcast, Bryan and a team of Mitsubishi Electric Trane HVAC US (METUS) managers (Mike Schaefer, Charles Miltiades, and Sly Grimm) discuss mini-split controls strategies.

Some contractors misunderstand what mini-splits are. Mini-splits CAN be ductless, but not all of them are ductless. Mini-split systems also have handheld controls, but those are not the only control options for mini-splits. Mini-split controls also come in wi-fi, wall-mounted, and wired varieties.

Another common misconception about mini-splits is that they do not work in the cold. While that used to be accurate, modern mini-splits can function well as heat pumps that integrate backup heat. That is especially when it is also tied into a ducted system.

A lot of thought goes into sensor placement, and contractors have many options as to where they can be placed. You can put wireless sensors in discreet locations, such as under the air return in the basement.

Lately, there has been a market shift towards a preference for multizone equipment, so the wireless controls help manage several units instead of just one; you can manage 30+ indoor units.

In general, homeowners are becoming more tech-savvy and are beginning to prefer tying all of their HVAC systems together and managing them all via one platform. As such, Mitsubishi controls can connect to smart home assistants, such as Alexa or Google. Mitsubishi mini-split controls also work with a cloud service that remembers data. However, a strong wi-fi system is necessary for these controls.

The Mitsubishi Electric team also covers:

Third-party controls and backup heat
Integrating with boilers for primary heat
Control placement
Multizone controls
Smart devices and signal strength
Innovative solutions

Learn more at mylinkdrive.com and METUS's YouTube channel.

Check out our handy calculators HERE.

Key System Performance Factors - Short 124 Jul 27, 2021

Show notes

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.

Copeland Scroll Compressor Multiples for Air Conditioning w/ Trevor Jul 22, 2021

Show notes

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.

Margin, COGS, Markup & Profit Confusion - Short 123 Jul 20, 2021

Show notes

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.

Planning and Layout of HVAC Projects Jul 15, 2021

Show notes

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.

Startup vs commissioning - Short 122 Jul 13, 2021

Show notes

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.

How to Make Mentorship Work w/ Eric Kaiser Jul 08, 2021

Show notes

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.

Alternatives for College That Parents Should Consider Jul 01, 2021

Show notes

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.

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