HVAC School - For Techs, By Techs

Latest Episodes:

Short 16 - Air Velocity is Useful Jul 30, 2018

Show notes

In this short podcast episode, Bryan covers how to measure air velocity directly at a return or supply and what those readings tell you.

Since many techs like to focus on CFM and static pressure readings, they can neglect air velocity in their measurements. Air velocity is the speed at which the air is moving. Conversely, static pressure is the force of the air against the sides of the ducts, and CFM is the air volume. We measure air mass in pounds (in the USA); when air is denser, you will have more pounds, but the volume will stay the same.

We primarily measure air velocity with a vane anemometer. Air moves through the vane and spins it, which informs the anemometer. That anemometer then gives you the reading. While airflow is the ultimate measurement, it is much better to take velocity measurements than none at all. Velocity can help you determine the CFM, but that requires knowledge that some techs don't have or are simply unwilling to apply. You need to know the size of the intake and have knowledge of the open/free area of the vent.

Velocity can help you determine how much throw you need to reach a certain distance. Velocity is a measure of feet per minute and can be applied to distance variables like throw. However, register sizing needs to come before measuring velocity. Velocity helps you figure out your throw and register sizing without relying on CFM measurements. Velocity can also help you identify noise issues, with higher velocities indicating noisier ductwork.

To reduce air velocity in cases where you have too much, you may need to use a balancing damper to throttle it back.

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.

Intro to Water Source Heat Pumps w/ Eric Mele Jul 26, 2018

Show notes

In today's podcast episode, Eric Mele walks us through the components of water source heat pumps, how they work, and what to look for. Water source heat pumps use water to transfer heat to and from the outdoor unit; the water takes the place of outdoor air in an air source heat pump.

These units have heat exchangers and water lines, but they otherwise operate exactly the same as any other heat pump. These units have reversing valves, which are commonplace on heat pumps, and they are energized by a typical O call. Water source heat pumps almost never have defrost boards, unlike air source heat pumps. However, these units may also have auxiliary heat, such as electric heat. Capillary tubes are the typical metering devices on water source systems; the refrigerant flow can reverse through the metering device and doesn't require a second metering device, unlike air source heat pumps. Some larger water source systems may have TXV systems, and the bulb goes very close to the compressor.

Water temperature will affect the cooling capacity of water source heat pumps. However, pressure and flow rates are also important factors to measure. You can measure the temperature differential across the heat exchangers and liquid line temperatures to determine if you have water flow issues.

The refrigerant and water counterflow; the water and refrigerant move in opposite directions. Piping quality is an extremely important concern in a water source heat pump. If the piping fails or is supported poorly, all of that water can flood out and cause a lot of damage.

Eric and Bryan also discuss:

Measuring water pressure
Scale buildup and neutralization
Capillary tube strainers and restrictions
Brazing
Fasteners

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.

Short 15 - Testing Capacitors, A Practical Approach Jul 24, 2018

Show notes

In this short podcast episode, Bryan Orr discusses the best practice methods for testing run capacitors in the field.

We understand the capacitor to be a voltage storage device. We can benefit from comparing the capacitor to a balloon that inflates and deflates with electrons as the alternating current changes (60 times per second). A capacitor causes a phase shift and allows there to be current on the start winding. So, when a run capacitor fails, you won't have current on the start winding.

The old-fashioned way of testing a run capacitor was to take an ohmmeter and charge/discharge the capacitor. Nowadays, we have capacitor testers, and many multimeters also have capacitance testers. Capacitance is merely a mathematical equation that you use when you compare the amount of voltage to the amount of current entering and leaving.

A good way to test a capacitor on a running system is to test it under load. You take the amperage of the wire feeding the start winding and multiply it by 2652. Then, you divide that product by the incoming voltage across the capacitor to get the capacitance. While this method is probably the most practical, it still has a caveat; some meters may have a hard time getting a proper amp reading on the start winding. So, tool accuracy will also determine your success when testing capacitors under load. To increase accuracy, make sure your wires are isolated from others. Under-load testing may also be unsafe in some cases, such as with a blower capacitor.

Testing with the system off is called bench testing, and it is slightly more accurate but does not represent under-load conditions. It will be more practical than under-load testing if the system is already off or if it is unsafe to test the capacitor under load.

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.

Seasons of HVAC Jul 19, 2018

Show notes

In this episode, Bryan Orr talks about how the seasons affect our HVAC work and how to manage stress during the busy season.

If you work in the trade, you will notice that we have busy and slow seasons. If you own a business, you understand the pressure that you're under to serve the community during those times. Hiring and training people for the busy seasons is difficult and may not be feasible for many companies. Fortunately, the busy season can bring out the good in other people who want to support their coworkers and community.

The summer tends to be the craziest season, especially in the hot southern states. We work long hours and sometimes deal with angry or frustrated customers. We definitely experience times when our bodies don't feel like they can take the workload. The summer is a hard time, but that hard time also gives us a chance to build our character and take pride in our work.

We remember those hard times during the cool season, winter. That's the time for Christmas parties, bonuses, and taking it easier around the shop.

The seasons of our work are like the seasons of our lives. We have times where we have to work extremely hard and others when we don't need to. We got into the trade because we wanted to do something that helps others in the real world. In our work, we build up that grit and strength of character so that we can appreciate the less physically demanding days later, especially when we get into management, but we may never truly give up our work completely. HVAC technicians keep that strength of character and wisdom from the hard seasons, and they hold onto those throughout their lives.

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.

Short 14 - The Voltage Drop Tool Jul 17, 2018

Show notes

In today's short podcast episode, Bryan discusses the voltage drop measurement tool, also commonly known as the voltmeter. You can also find this voltage drop tool on multimeters. You use them to check voltage drops, NOT the actual voltage.

We get voltage values from a potential difference. So, we check for these differences via voltage drops. For example, you can determine if contactor pitting or carbon buildup is problematic by measuring the voltage across contact points. Your meter will read the voltage drop.

We don't often deal with intentional series circuits. However, we can see unintentional series circuits when switchgear or wiring adds more resistance than it should. The voltage drops when that happens. You can also use a voltmeter to locate an open circuit; when you no longer see voltage as you walk through a circuit, you can determine that you have found an opening.

An HVAC system with low current may have a cumulative voltage drop, which is the total drop of all the voltages in the system, including the crankcase heater and compressor windings. Kirchoff's second law helps explain the behavior of the voltage in a system; the law states that for a closed-loop series path, the algebraic sum of all voltages around any closed loop is equal to zero.

Any time you use a voltmeter, your two leads communicate the voltage drop from one lead to the other, whether those are across contactors or different points on the same wire. When finding an undesigned voltmeter is most effective when used under load. You will see a massive voltage drop when you use a voltmeter under load; otherwise, you will see a much smaller voltage drop.

Check out Refrigeration Technologies HERE.

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

Commercial vs. Residential w/ AK HVAC Jul 12, 2018

Show notes

In today's podcast episode, we have a conversation about the pros and cons of commercial vs. residential HVAC with Andrew Greaves. (You may know him as AK HVAC on Youtube. Check out his channel HERE and his comedy channel, HVAComedy, HERE.)

In many cases, young people don't know if they want to go into commercial or residential HVAC, or residential techs may think about getting into commercial HVAC. Commercial HVAC may include RTUs, chillers, market refrigeration, or industrial refrigeration. Commercial HVAC/R also includes a lot of control systems. By comparison, residential HVAC almost exclusively deals with comfort cooling.

Even though it may seem as though commercial HVAC requires more specialized schooling, that isn't necessarily the case. Schooling will especially help with commercial HVAC, but it's not required. The desire to learn is much more important than schooling. (Be willing to unlearn your bad habits, too.) If you enjoy working on large equipment and machines, commercial HVAC may be right for you.

Hours are also a bit different in commercial vs. residential HVAC. In many cases, commercial HVAC still has on-call time, and the hours may be slightly more regular than residential HVAC. (However, some facilities like hospitals may require work at irregular hours.)

If you wish to become an entrepreneur, you'll probably have more success with residential HVAC. The business models are very different, and you'll have more freedom with pricing when you start up a residential business. Commercial work is process-oriented per the customer, and there is a lot of negotiation that goes into a contract. (You'll also be more likely to stumble across lawsuits in commercial HVAC.) If you want to start up a business or have an entrepreneurial spirit, then residential HVAC might be right for you.

We also discuss:

Mechanical/technical aptitude
People skills
Commercial vs. residential shops
Service contracts
Corporate environments
Commercial HVAC technologies
Commercial HVAC specializations
Profitability as a tech vs. a business owner

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.

Short 13 - 3 things the condenser does Jul 10, 2018

Show notes

In this short podcast, Bryan covers three things that the condenser does. He also explains where those things happen and what those they mean in terms of system operation.

The evaporator coil does two things: boiling and superheating. However, a condenser does three things: desuperheating, condensing (changing state), and subcooling.

Desuperheating occurs early on in the condenser, at the top. Refrigerant enters the condenser as a highly superheated vapor. Even though we have a few degrees of superheat in the suction line, the discharge line's superheat is a lot greater. (For context, the suction line will feel cold to the touch, but the discharge line will burn you.) The compressor skyrockets the superheat through the heat of compression and sends that refrigerant to the condenser via the discharge line. So, desuperheating reduces the temperature from 160+ degrees to the saturation temperature, about 100 degrees.

In the middle of the condenser coil, the refrigerant stays at saturation. However, it continues rejecting heat. That is because the refrigerant is undergoing a phase change from vapor to liquid; it rejects heat in the form of latent heat even though the temperature stays the same. Once all of that latent heat has been rejected to the air, the refrigerant becomes fully liquid. Then and only then can the refrigerant start to drop its temperature.

The temperature of the liquid refrigerant drops at the bottom of the condenser coil. We call that process subcooling. Subcooling refers to the temperature of a liquid below the saturation point. For example, if the saturation point is at 100 degrees but the liquid refrigerant is 95 degrees, you will have 5 degrees of subcooling. In general, a common subcooling range is 8-14 degrees.

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.

Short 12 - The First 4 Rules to Learn Jul 05, 2018

Show notes

Many techs have said, "That's the first thing you should have learned in school." In today's short podcast, Bryan talks about the four rules that have his vote for the first things to learn in school.

These four rules don't just apply to HVAC work; they apply to science and the world as a whole. They describe how the forces in our world work in our HVAC careers and our everyday lives.

The overarching theme of these rules is that high goes to low. Gravity is the prime example of this rule; if you drop something from a high place, it will fall to a lower place. There is a potential energy difference between high and low, whether you apply that to a ball rolling down a hill, voltage, or a sine wave.

The first rule is that high pressure goes to low pressure. The compressor applies lots of pressure to the low-pressure refrigerant inside of it.

The second rule is that high temperature goes to low temperature. We transfer heat from the inside of the house to refrigerant inside the evaporator coil. (Remember: temperature is an AVERAGE measure of molecular activity.)

The third rule is that high voltage goes to low voltage. Electrons move from the higher energy state to the lower energy state.

The fourth rule is that high humidity goes to low humidity. For example, two air masses with different humidity contents can be separated by a cloth. The higher-humidity air mass will diffuse some of its moisture across the cloth to the lower-humidity air mass. This process creates a stasis across the two air masses.

Everything in the world tends towards equilibrium.

Learn 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.

Coil Cleaning with John Pastorello Jul 03, 2018

Show notes

In this episode, we speak with the founder of Refrigeration Technologies, John Pastorello. He also tells us all about chemicals, cleaners, and HVAC coil cleaning.

John Pastorello started out working as a chemist before becoming an A/C installer. He initially planned to return to a lab job, but he found his niche in HVAC work. He took his chemistry experience to his HVAC work to develop better chemical products. It all started with his decision to make a better leak detector fluid (Big Blu). However, John knew that you can't build a company around one product, so Refrigeration Technologies was born.

An ideal condenser coil cleaning starts with having the correct dilution ratio. There is a bell curve of effectiveness, and using too much cleaner can be as ineffective as using too little cleaner. Typically, we can optimize soil removal with a dilution of one part cleaner to five parts water. You can pre-rinse with enough pressure to "punch through" the coil. Then, you can apply the foam detergent. Foam guns can make it easy for soil molecules to bond to the detergent. John recommends starting at the bottom and working upwards, keeping the foam gun close to the condenser the entire time. Give the detergent some time to penetrate through the soil, and then rinse. Repeat the process for maximum effectiveness, upping the dilution ratio this time.

Evaporator coils can develop a unique problem: biofilm. Very few cleaners attack that protein biofilm. EVAP+ coil cleaner contains enzymes that can digest biofilm and remove it over time.

John and Bryan also discuss:

Acid vs. alkaline products
"Green" products and performance
Cleaning products and bodily hazards (itching, scarring, etc.)
Foam cleaning
Coil brushing
Testing new chemicals
Chlorine corrosion on aluminum oils
Pan and drain cleaners

Visit the Refrigeration Technologies website and learn more about their products at refrigtech.com.

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

Danfoss ERC213 Parameters Review Jun 27, 2018

Show notes

In today's podcast episode, Jonathan Romberg comes on to discuss how the Danfoss ERC 213 works and reviews its parameters with us.

Timestamps: 10:30 – Key Features

10:41 – Voltage Protection

10:56 – Compressor Protection

14:43 – Applications

15:15 – App 0 No predefined application

15:28 – App 1 Medium temperature ventilated refrigeration units with timed natural defrost

15:52 – App 2 Medium temperature ventilated refrigeration units with timed electrical defrost

16:03 – App 3 Low temperature ventilated refrigeration units with timed electrical defrost

16:13 – App 4 Medium temperature ventilated refrigeration units with electrical defrost (by temperature)

16:26 – App 5 Low temperature ventilated refrigeration units with electrical defrost (by temperature)

16:37 – App 6 No predefined application with a simplified list of parameters

19:45 – Sensors 22:06 – Basic Groups of Parameters 23:09 – r-- Thermostat

23:12 – r00 Temperature setpoint

23:24 – r01 Differential

23:32 – r02 Min setpoint limitation and r03 Max setpoint limitation

24:02 – r04 Display offset

25:19 – r05 Display Unit (°C/°F)

25:33 – r09 Calibration of Sair

25:47 – r12 Main switch

27:17 – r13 Night set back

27:48 – r40 Thermostat reference displacement (offset temperature)

28:30 – r96 Pull-down duration and r97 Pull-down limit temperature

29:06 – A-- Alarms

29:13 – A03 Delay for temperature alarm during normal conditions

30:15 – A12 Delay for temperature alarm during pull-down/start-up/defrost

31:00 – A13 High-temperature alarm limit (Cabinet/Room)

31:34 – A14 Low-temperature alarm limit

31:55 – A27 DI1 delay and A28 DI2 delay

32:17 – A37 Condenser high alarm limit

32:41 – A54 Condenser high block limit

33:45 – A72 Voltage protection enable

34:03 – A73 Minimum cut-in voltage and A74 Minimum cut-out voltage

35:04 – A75 Maximum Voltage

37:37 – d-- Defrost

37:49 – d01 Defrost method

38:32 – d02 Defrost stop temperature

38:50 – d10 Defrost stop sensor

40:51 – d03 Defrost interval

41:16 – d04 Max defrost time

43:38 – d05 Defrost delay at power up (or DI signal)

44:29 – d06 Drip delay

44:49 – d07 Fan delay after defrost

45:49 – d08 Fan start temperature after defrost

47:21 – d09 Fan during defrost

47:40 – d10 Defrost stop sensor (part II)

48:16 – d18 Compressor accumulated runtime to start defrost

50:04 – d19 Defrost on demand

53:26 – d30 Defrost delay after pull-down

53:53 – F-- Fan control

54:03 – F01 Fan at compressor cutout

55:00 – F04 Fan stop evaporator temperature

55:51 – F07 Fan ON cycle and F08 Fan OFF cycle

56:28 – c-- Compressor

56:37 – c01 Compressor minimum ON time

56:47 – c02 Compressor minimum OFF time

57:01 – c04 Compressor OFF delay at door open

57:51 – c70 Zero crossing selection

58:22 – o-- Others

58:37 – o01 Delay of outputs at startup

59:11 – o02 DI1 configuration

1:01:36 – o05 Password

1:02:08 – o06 Sensor type selection

1:02:27 – 015 Display resolution

1:03:31 – o23 Relay 1 counter, o24 Relay 2 counter, and 025 o24 Relay 3 counter

1:04:13 – o37 DI2 configuration

1:04:52 – o61 DI2 configuration

1:05:07 – o67 Save settings as factory

1:05:39 – o71 DO2 config

1:06:23 – o91 Display at defrost

1:07:04 – P-- Polarity

1:07:06 – P73 DI1 input polarity and P74 DI2 input polarity

1:07:32 – P75 Invert alarm relay

1:07:59 – P76 Keyboard lock enable

1:08:21 – u-- Readouts

1:08:30 – u00 Controller Status

1:09:37 – u01 Air temperature (Sair)

1:10:12 – u58 Compressor relay status, u59 Fan relay status, u60 Defrost relay status, and u63 Light relay status

Find out more about the Danfoss ERC 213 HERE.

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.

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