HVAC School - For Techs, By Techs

Latest Episodes:

Short #11 - Superheat, The True Meaning Jun 25, 2018

Show notes

In this podcast, we discuss the real significance of superheat and why it is much more than "a way to set the refrigerant charge on a fixed metering device."

Superheat is the temperature of a vapor above saturation. Many people use it to set the charge on a piston or fixed orifice, but that's not its only purpose. Superheat is a much more important reading than that, and you can take that measurement at a few different places. For example, most of us measure it outside. However, to determine how the system is feeding the evaporator coil, we would take superheat at the evaporator outlet (6-14 degrees is normal for a TXV). However, superheat matters regardless of the metering device type.

Zero superheat indicates that the refrigerant is still at saturation; it is in a mixed state, not entirely vapor. So, we know that we are "overfeeding" the evaporator coil. The boiling process does not finish in the evaporator; it continues into the suction line. Overfeeding is a problem because our evaporator might not boil off all the refrigerant, and we could send liquid to the compressor. The system may be overcharged, or the evaporator load may be too low.

Excessive superheat indicates that the refrigerant is boiling off too quickly in the evaporator coil. In those cases, we are starving or underfeeding the evaporator coil. The boiling process ends too early in the evaporator coil. The system may be undercharged or have too much load on the evaporator coil.

When our superheat is within the proper range, we are feeding the evaporator coil correctly. The majority of that evaporator coil is being fed with boiling refrigerant.

Learn more about Refrigeration Technologies at refrigtech.com.

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

How to Go From Tradesman to Franchise Empire Jun 21, 2018

Show notes

This is the story of WITH JOSHUA NICHOLLS FROM PLATINUM ELECTRICIANS and how he went from pulling wire, to creating a franchise empire to giving back.

PCO Air Purification with Jon Bennert Jun 19, 2018

Show notes

In today's podcast, Jon Bennert with Air Oasis talks about photo-catalytic oxidation (PCO) air purification. He explains how it works and what it does.

The NANO products are PCO-type technologies. These technologies were initially developed for NASA storage systems on the International Space Station. Photo-catalytic oxidation (PCO) products work to reduce or sterilize pollutants or organisms in the air by using light. Sunlight produces UV rays that can kill nasty germs in the air; PCO products work similarly and may have UV lamps or not. (NANO units use UV lighting.)

The UV isn't all that effective by itself. However, UV light can produce pollutant-fighting ions when the UV hits the coating within the air purifier. These ions are typically hydroxyl ions, which are more effective than ozone but don't last very long. So, PCO products are most effective when they have a large surface area with the catalyst.

You can get all sorts of bacteria, yeast, and fungi inside a home. Humidity will usually only make those worse. Not to mention, you also have VOCs from cleaners and building materials, which may smell nice but greatly reduce your air quality. Humans also create plenty of pollution through humidity and dead skin cells. Air purifiers can help you deal with all of these air quality reducers. The NANO is unique, as it can run only when the fan is on and reduce ozone byproducts in your ductwork.

Bryan and Jon also cover:

UV lighting in the ductwork
Simple organisms vs. complex organisms and defense mechanisms
Ozone and ozone-generating equipment
PCO byproducts and efforts to reduce those
NANO sizing
How Air Oasis tests the product's cycles
NANO vs. competitors
Improvements to the NANO over time
How techs can recommend and sell IAQ products more effectively
Air quality testing

Find out more about Air Oasis at airoasis.com.

Check out Refrigeration Technologies HERE.

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

Short #10 - Air Has Weight and Takes up Space Jun 15, 2018

Show notes

In this episode, we talk about air as a form of matter. We cover air volume, density, weight, and mass and why it matters to you.

So, air has weight and takes up space. When we measure air, we typically measure it by volume (CFM or cubic feet per minute). When we say that air takes up space, we are referring to air volume. A cubic foot of air is equivalent to a 1'x1'x1' box of air. When we measure CFM, we measure how many boxes of air we move per minute. We usually want around 400 CFM per ton, though the exact number varies by system, function, and ambient conditions. Lower CFM per ton is better for moisture (latent heat) removal, while higher CFM per ton is better for sensible heat removal.

Air also has weight. When we are at higher altitudes, the air is thinner and less dense. Therefore, the air has less weight. Standard air weighs about 0.75 pounds per cubic foot (box of air). If you multiply the 400 CFM per ton standard by the standard air weight, you get 30 pounds of air per minute. That pounds-per-minute value is what we call the mass flow rate. The air density affects mass flow rate; temperature and relative humidity can change the density of air. So, the volume is the box, but density (which affects mass) is what's in the box.

Even though our goal is to move pounds of refrigerant (mass), we care about CFM (volume) because fans move air regardless of density. The blower affects the CFM, but the mass flow rate is more important to the coil. We have to adjust our volume flow rate to achieve a proper mass flow rate.

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.

Special EP Inverter Equipment With Ralph Wolf Jun 12, 2018

Show notes

In today's podcast episode, Ralph Wolf comes on and discusses inverter equipment. He also talks about Mitsubishi, Bosch, and what he's been up to nowadays.

An inverter system can vary its output of rated capacity. Inverter equipment makes load matching much easier and is generally comfortable. These systems maintain temperatures in tighter ranges and remove more moisture with longer runtimes.

Mitsubishi is one of our top ductless systems at Kalos. Due to building codes, they are one of the only systems we can use in sunrooms and lanais. However, the building codes technically allow those systems to be used for dehumidification. Mitsubishi mini-splits can perform below average if they aren't sized correctly (even if they appear to be correctly sized).

Bosch is another manufacturer that makes inverter-driven equipment. Like Mitsubishi, Bosch is based in Asia but has been making massive strides in the American market. They use the same Y and O calls you'd see on typical heat pumps. Bosch equipment can ramp its compressor up and down to accommodate the load. You can also use a larger unit on a smaller air handler. You can also choose from a variety of coil temperatures and adjust the fan to reach your desired dehumidification. However, inverter board issues are quite common right now. We should expect some of these issues to clear up with future versions of the equipment.

Breakdowns are normal for new technologies, but Bosch has gone above and beyond to fix issues by bringing their engineers to the USA to analyze our faulty equipment. The future is bright for Bosch and inverter technology.

Bryan and Ralph also discuss:

Choosing new inverter equipment
Improper compressor operation
Compressor sizing effects on operation
ECOER systems
Inverter technology and controls
Short cycling prevention
Heat dissipation issues in capacitors
Ductwork for inverter equipment

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.

Basic Refrigerant Circuit Revisited (Part 2) Jun 07, 2018

Show notes

Part 2 - Bert (Kalos Tech) and Keiran (Kalos Apprentice) join Bryan in the studio to talk through the basic refrigerant circuit and how it functions. They talk compressor, condenser, metering device, and evaporator as well as the four lines and the states of the refrigerant as it travels.

The four lines that move refrigerant are the suction line, discharge line, liquid line, and expansion line. The suction line moves cool superheated vapor from the evaporator to the compressor. Then, the discharge line moves very hot superheated vapor from the compressor to the condenser. The liquid line runs warm subcooled liquid from the condenser to the metering device. Of the four lines, the expansion line is a bit controversial, as it doesn't even exist in some systems. It runs from the metering device to the evaporator and expands the liquid refrigerant so that some of it can flash at the evaporator inlet. You may see an expansion line on mini-splits, but many typical residential split systems will lack an expansion line.

The suction line draws vapor to the high side of the system, and the discharge line discharges high-pressure vapor to the condenser. A liquid line gets its name from the fact that it carries liquid to the metering device. The expansion line gets its name because it expands the liquid/vapor mixture (reducing pressure, continuing the metering device's job).

We also discuss:

Evaporation vs. boiling
Condensing temperature over ambient (CTOA)
Superheat and subcooling
Line dryers
Saturation
Feeding evaporator coils
Where to measure superheat

Basic Refrigerant Circuit Revisited (Part 1) Jun 05, 2018

Show notes

Part 1 -Bert (Kalos tech) and Keiran (Kalos apprentice) join Bryan in the studio to talk through the basic refrigerant circuit and how it functions. They talk compressor, condenser, metering device, and evaporator as well as the four lines and the states of the refrigerant as it travels

They talk about the compressor, condenser, metering device, and evaporator as well as the four lines and the states of the refrigerant as it travels. We have already covered all of the basic components in earlier podcasts, which you can check out HERE; we focus more on accessories, refrigerant movement through the circuit, and scientific concepts in this episode.

We also discuss:

Pumps vs. compressors
Refrigerant and air-cooled compressors
Flooding a compressor with liquid refrigerant
Crankcase heaters
Temperature vs. heat vs. BTUs
VRF vs. ductless

Making of a TV Show About Home Performance May 31, 2018

Show notes

In today's podcast, I talk with Corbett Lunsford about his new show about home performance and diagnosis. Home Diagnosis airs on PBS in winter 2018. Even though Home Diagnosis mostly deals with building performance, HVAC work is a large component of overall home performance.

Corbett Lunsford used to be a pianist before becoming a building performance expert. He was already familiar with media and decided to launch a YouTube channel. The goal of the YouTube channel was to bring visual information and practices to the masses. Since then, he has been working to create a much larger mass media project to let HVAC professionals and consumers know about building performance. Home Diagnosis is Corbett's means of bringing awareness to whole-home performance as buildings become much tighter.

The main goal of Corbett's TV show is to put home performance on the same level of awareness as car performance and athletic performance. Many factors contribute to comfort, but it is not all the responsibility of the HVAC technician. The home performance field addresses ductwork and the overall design of the house to provide the most accurate and holistic comfort solutions. The TV show also empowers consumers to talk to experts to help them achieve their comfort targets, not just request a certain repair.

While HVAC technicians make up for losses in a building enclosure, building science assesses the issues with the enclosure.

Bryan and Corbett also discuss:

Contractor mistakes
Good and bad practices for fixing ducts
"Seeding" your clients and building trust
Giving customers options to choose other contractors
Sponsorship offers and participation
Humid Climate Conference

Learn more about Home Diagnosis HERE.

Check out Corbett's Home Performance YouTube channel HERE.

Check out Refrigeration Technologies HERE.

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

Sealing Ducts From the Inside w/ Sean Harris May 29, 2018

Show notes

Sean Harris with Positive Energy and Aeroseal Austin sat down with me at the humid climate conference and talked about how to seal ducts from the inside with Aeroseal. We regularly see air leakage by poor connections, especially when we deal with flex ducts.

When a house comes under negative pressure, it draws a bunch of air in from the outdoors or unconditioned spaces. Unfortunately, that air can be very low-quality in humid climates. The humid air can be even worse if it comes from an unconditioned space where you have leaky supply ducts. So, we can prevent that nasty attic air from coming in if we seal ducts from the inside out.

Aeroseal goes inside the ducts and is a good sealant that can be compared to Fix-A-Flat for a car tire. When pressurized air leaks from the duct, Aeroseal makes its way to the leak and expands over it. Aeroseal doesn't coat the ductwork; it merely travels to leaks and seals them up. Aeroseal looks like a mist and can seep out of leaks. So, as an extra measure of caution, be prepared to protect a customer's belongings in an attic or crawlspace.

However, sealing ducts requires a holistic approach. We need to perform quite a few tests to get an idea of the building envelope and duct design before we consider ways to seal or replace the ductwork. Sean enjoys paying attention to duct sizing and understands that sealing ducts could make a customer's comfort issues even worse in an oversized duct system.

So, Aeroseal is a great product for leaky ducts of a good size. Aeroseal is a long-lasting solution for duct leaks, but it is not a magical fix-all product.

Learn more about Aeroseal HERE.

Check out Refrigeration Technologies HERE.

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

Short #9 - Commercial Maintenance May 24, 2018

Show notes

Today's short episode covers five things residential techs need to consider when tasked with doing maintenance on a commercial system. We mostly talk about light commercial package unit maintenance in this episode.

If you come across fresh air filters, be sure to wash those. Some commercial units have economizers that bring in fresh air, but not all fresh air is high-quality. Wash those filters to avoid pollen and other types of outdoor gunk buildup.

Then, you'll want to check and adjust belt tension. Make sure you adjust the belt in each direction correctly; don't get them too tight. Otherwise, you might break or stretch the belt. You may also wear out the bearings or cause higher amperage on the blower motor. In general, you want the belt to be tight enough not to slip off and no tighter. We recommend using the Browning belt tension tool. You may also consider replacing the belt if need be.

You'll also want to align pulleys. Don't just align the edges; align the entire pulley. If you're dealing with sheaves, you can adjust those to tweak your CFM rate. Make sure the motor mounts are square, too.

The next maintenance step is familiar with residential techs: properly wash the condenser coils. However, you may have to "split" the coils; you'll pull them apart and put them on a piece of wood as you separate them. Even though it sounds difficult and time-consuming, splitting the coils is the only way to do a thorough cleaning.

Lastly, you'll want to check the phase balance on three-phase equipment. Phase imbalance can lead to the death of a motor; more than 2% of imbalance can cause issues, and 4% indicates a severe problem.

Check out Refrigeration Technologies HERE.

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

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