HVAC School - For Techs, By Techs

Latest Episodes:

Analog & Digital Manifolds w/ James Bowman Oct 11, 2018

Show notes

James Bowman returns to the podcast to talk about analog vs. digital manifolds. He also explains why both of them may still have a place in the industry.

Pricing is a key difference between analog and digital manifolds. Analog manifolds tend to be less expensive and will suffice just fine for techs who don't require readings with a lot of detail. While digital manifolds will be more expensive, they can also give you more precise, detailed readings. So, digital manifolds have a slight leg-up in terms of resolution as well; these manifolds are generally better for critical-charge or MicroChannel systems.

Learning to take readings on analog manifolds early on may be advantageous for young or inexperienced techs. You learn more about superheat, subcooling, and interpreting readings when you start off with an analog gauge manifold. The process of taking readings on digital gauges is automated; therefore, digital gauges are less effective as learning tools.

If you want to recover refrigerant, you might be better off using an analog manifold. These are less expensive and may be better equipped to deal with the nasty contaminants inside a system. Digital manifolds are more expensive and should not be exposed to contamination if you want them to last a long time.

We often use accuracy and resolution interchangeably, but accuracy refers to the correctness of a reading. Resolution refers to the scale of the measurement. Digital manifolds usually have advantages in both of these areas, as they can usually take finer readings.

James and Bryan also discuss:

Critically charged systems
Charging and recovery
Hoses
Ductless systems
Technological and practical changes in our industry's future
Using probes to take readings
Single-port manifolds
Applications where accuracy is most important
Causes of inaccuracy
Calibrating probes and other tools

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 #25 - A Costly Screwup Oct 09, 2018

Show notes

In this short podcast episode, we share some quick tips about keeping panels and insulation in place to avoid a costly screwup.

Often, technicians will use an impact driver too aggressively. If you feel it begin to clutch, that means that the driver is actually impacting, and that means you're going too far. When that happens, you can strip out the screws, which can be a serious problem on larger equipment. On RTUs and other large commercial equipment, panels can fall off if you strip out those screws, which can be a costly screwup.

So, don't strip out screws. Even if you need to put the screws in by hand or with a regular driver instead of with an impact driver, you'll see better long-term results. On normal drivers, you can also set the clutch so that the driver stops before it can strip out the screw threads.

When panels fall off, the insulation can encounter issues as well. If the insulation peels off, please put it back on. Don't be afraid to use a little bit of spray glue to help mount that insulation to the inside of the panel. After using spray glue, you can finish mounting the insulation with some butyl tape on the edges, which has a heavy-duty adhesive and should last a long time. (Silver tape is okay, but it isn't nearly as strong as butyl tape.)

When panels come off due to screws stripping out, they can blow away in extreme weather. In Florida, we have hurricanes in the summer and fall, so flying panels should be prevented at all costs. In some cases, you can even use a slightly larger screw to replace a missing screw if need be. Self-tappers also aren't the best screws you can use.

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.

Are Refrigerant Additives OK? Oct 04, 2018

Show notes

John Pastorello, the HVAC chemist, comes on the podcast and discusses refrigerant additives such as acid inhibitors, oil enhancers, dyes, and leak sealants with his knowledge and some things to consider.

Acid neutralizers are refrigerant additives. Oil works best in a slightly acidic environment, and these additives can change the pH of the system. If the pH becomes neutral or alkaline (basic), then the system will not operate as it should. Acid scavengers won't change your pH, but they are usually alcohol-based, which may attack aluminum in your system and make your windings brittle. Instead of relying on acid-reducing refrigerant additives, the best solution is to use and responsibly replace suction driers.

Corrosion inhibitors are also refrigerant additives. OEMs sometimes use these on their own equipment or recommend the usage of corrosion inhibitors. However, these can come with their own set of impurities. These impurities can be even more detrimental if the products come from a foreign market.

Solvent-type products assist oil return by reducing the oil viscosity. However, these solvents can cause the oil to foam and can quiet your compressor down. These foaming agents have no positive effects on your system; the compressor may run more quietly, but solvents have no effect on the amperage.

Leak sealants are other additives. These started in the automotive industry, and manufacturers would void warranties on cars that had leak sealants in their systems. Leak sealants introduce solid particles into your system to patch up a leak. However, we can't actually repair leaks by patching them with fine solids.

John and Bryan also discuss:

Marketing tactics
Additive testing
Solutions for excessively acidic systems
Oil sample analysis and testing for burnouts
Suction drier usage and pressure drops
Diluting corrosion inhibitors
Non-polymer leak sealants

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 #24 - Hard vs. Soft Copper Oct 02, 2018

Show notes

Many technicians use hard or soft copper without thinking about which application is best for which. In this short podcast, Bryan talks about where to use each. He also covers some hanging and strapping strategies.

Residential service technicians typically work with soft copper. Conversely, commercial techs are probably much familiar with the hard variety. Both hard and soft types are good for specific applications.

If you need to work the copper, then the soft type is best for that. You can bend it by hand or with a bender without too much trouble, and it is ideal for flaring and swaging. However, it does not hang well and is not very structurally sound. If you need to hang copper through an attic or light commercial space, then you're really better off with the hard type. The soft kind also doesn't look quite as nice as its hard counterpart when you use it to feed several condensers with a line set.

Hard copper is straight, rigid, and holds up much better than the soft kind when it must be strapped, and it sometimes comes with rubber plugs. Strapping is not a practice that we commonly think about in residential HVAC, but we still need to strap our piping appropriately. We can use Unistrut and clamps to strap our piping correctly. You can bend, swage, and flare hard copper, but you must heat it before you work it; the hard variety can take a lot more abuse than soft copper and is much more durable. You also probably can't transport this type of copper in a van easily, as it can come in very long segments.

Check out Refrigeration Technologies 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.

How to Make a Flare That Won't Leak Sep 27, 2018

Show notes

Kevan Mayer with NAVAC comes on and talks all about flaring best practices step by step. From cutting to reaming to torque wrenches, we cover how to make a flare from start to finish. The goal of making a good flare is to reduce leaks as much as possible, especially on ductless units and in commercial HVAC/R.

When you make a flare, you have to make sure the depth is correct and consistent, especially on R-410a systems. NAVAC makes various flaring tools, including fast battery-powered ones, that can help you get a consistent depth on your flares. You can learn more about some of their flaring tools HERE.

You start off making flares by cutting your tubing. Make sure you have a clean, square cut. Using a sharp tool cutter is the best way to make sure that you get that clean cut. Tighten your tool down in increments. Cleaner cuts make deburring/reaming easier.

Assembly lubricants like Nylog and oil are excellent products to help you make a flare if used correctly. You don't want to let the oil or synthetic lubricants drip into the tube. Only use a little bit of these products, as too much Nylog on the threads can also change your torque spec. You can also put these lubricants on the cone of your flare tool.

When assembling a flare, make sure that you follow the manufacturer's specs regarding height and flare nuts. Be mindful of the torque you apply during the assembly. Use a backing wrench and torque wrench for assembly.

We also discuss:

Reaming/deburring practices
Differences in line sets with different refrigerants
Flares in residential and commercial HVAC
Flare gauges
Torque specs and torque wrench usage
Pressure considerations
Leakage, pressure testing, and decay testing

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.

Check out our handy calculators HERE.

Chilled Water Air Handlers Sep 20, 2018

Show notes

In today's podcast, Eric Mele and Bryan talk about chilled water air handlers, their valve configurations, and some key things to look out for.

In a chilled water system, we don't have the traditional evaporator and condenser in our HVAC system. Instead, we merely have a hot coil and a cold coil. We don't work with a direct-expansion refrigerant that changes state. We merely move water. These chilled water systems can be used in residential and commercial applications.

With almost all applications, both pipes will be insulated in the same size. You may also see an actuator on the outside, which impacts water flow and attaches on top of the valve. Chilled water systems can come in a two-pipe configuration or a four-pipe configuration. The supply water on chillers typically runs about 44 degrees (F).

The water loops on chilled water air handlers may have either a two-way valve or a three-way valve. You'll generally see a two-way valve on systems with variable frequency drives (variable water flow). Conversely, three-way valves will typically be on systems with more constant water flow; the pump runs at a constant volume, so the three-way valve acts as a bypass. If you must replace a valve, make sure you use the correct valve for the application.

These chilled water air handlers don't easily allow you to get readings from them. Once you factor insulation in, you may not have access to pressure ports at all. Some larger air handlers may have gauges installed, but they may not be accurate.

Eric and Bryan also discuss:

Insulation
Diverting vs. mixing on three-way valves
VAV system similarities
Line voltage controls and fan speed
Challenges and building maintenance staff
Air bleeds
Actuators

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 #23 - Intangible Soft Skills Sep 18, 2018

Show notes

In this short podcast episode, Bryan gets feedback on a podcast topic from Andy Holt. Per Andy's request, we discuss some intangible soft skills required to be a top-level technician in the HVAC trade.

Overall, a technician needs to be aware of the people and things in their surroundings. These techs are in tune with their customer's emotions, the pets, and the space where they work. A good technician is thoughtful but has the ability to let things go and not let their bad experiences overwhelm them. Many technicians that fit both of those descriptors are calm and focused by nature, and they are often positive people; happy techs are better communicators with customers.

Eye contact is important in the right amount. Customers want to know that you're paying attention to them. Customers also want to see action; they want to see you physically working on their system and taking measurements. Give the system a thorough check to find the most thorough diagnosis, even if you go into the job with an idea as to what that diagnosis is.

Cleanliness is a way for you to show respect for your customer's home or site. Use drop cloths and wear shoe covers to show that you care about keeping the site clean. Cleanliness is a branch of the overall idea of professionalism. Our image of professionalism is always evolving, but in the present day, you still want to use classy language and avoid looking like a slob. Most of all, professionalism stems from a central concern for the customer; spend less time talking and more time listening.

Organization in paperwork, processes, your work vehicle, and your toolbag is another one of those critical intangible soft skills. You exude professionalism when you are neat and have a structured process to guide you through your work.

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.

Refrigeration Temperature Controls w/ Chris Stephens Sep 13, 2018

Show notes

Chris Stevens from HVACR Videos on YouTube comes onto the podcast and talks about some refrigeration temperature controls basics. You can check out his YouTube channel HERE.

Although we have temperature controls in HVAC work, we will see slightly different ones in refrigeration work. The biggest difference is really the temperature itself; we're attempting to bring the box temperature down, so we will be dealing with much lower temperatures in refrigeration. The box and evaporator coil temperatures are the most important temperatures to be aware of in reach-in refrigeration, as they directly relate to pressures.

A standard pressure control opens or closes when pressures fall or rise. Your typical low-pressure control will open on a pressure fall and close on a pressure rise. We can use these as loss-of-charge switches or use them with the pressure-temperature relationship as evaporator temperature controls. However, pressure controls can be quite inaccurate. You absolutely CANNOT "set it and forget it" with these controls; you will likely have to make some adjustments, especially if you have long line sets. We also need to consider defrost in our strategies.

Constant cut-in controls are other common control strategies. These are simple controls with a sensing bulb in the evaporator coil that senses evaporator temperature as closely as possible without being a pressure control; they also turn on at a set temperature. These refrigeration temperature controls are quite accurate, but they can be difficult to use properly because they also pick up lots of other vital signs from the system.

Chris and Bryan also discuss:

TD vs. delta T
K-type thermocouple calibration
Wrap-up procedures for refrigeration jobs
Self-defrosting with pressure controls
Constant cut-in control sensing bulb placement
Service gauges
Frost buildup in medium-temperature applications
Digital controls
Controls based on product temperature
Universal and aftermarket controls
Air-sensing temperature controls

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 #22 - Mineral & POE Oil Sep 11, 2018

Show notes

Bryan talks about the differences between mineral oil (MO) and POE oil, the advantages and disadvantages of using them, and when to use them.

Mineral oil (MO) is what we've used for a long time. We like using it because it's very stable; it may have an affinity for moisture, but it is not nearly as hygroscopic as POE oil. Vacuum pump oil is a highly refined mineral oil, and it works so well because it's able to lock in moisture as those non-condensables get sucked out of the system. It is still not much of a solvent compared to POE oil, though.

However, the refrigerant may have a hard time carrying mineral oil through the system. So, pipe size, pitch, and trapping are important considerations when you're dealing with mineral oil.

POE (polyol ester) oil works much better with newer refrigerants, especially R-410a. These new refrigerants can't carry mineral oil effectively, and so they rely on POE oil, which moves with those refrigerants a lot more easily and doesn't just sit in the evaporator coil. Oil should stay in the compressor, but oil loss will happen over time and should move back to the compressor with the refrigerant. POE oil works with new refrigerants, but it also works with R-22. Overall, POE oil is very miscible, which means that it moves with refrigerant very well.

However, POE oil is reactive and acts as a solvent. The POE oil can pick up contaminants a lot more easily than mineral oil, which can wreak havoc on your system. POE oil reacts with moisture to become acidic, which can lead to issues like burnout. (Note: POE oil does NOT react with mineral oil!)

Bryan also covers:

Refrigerant velocity
Oil return
Acid scavengers
Retrofits

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.

Small Refrigeration Maintenance Procedure Sep 06, 2018

Show notes

Eric Mele returns to the podcast to discuss quality cleaning and maintenance procedures for small refrigeration systems. These small refrigeration systems include reach-in refrigerators and open-air cases on grocery sales floors.

Filthy condenser coils are problems in many HVAC applications, but they're exceptionally nasty in some small refrigeration applications; proximity to food residue (grease, sugar, etc.) makes condensers get dirty quickly. Use plastic-bristle brushes to clean the bulk of the soil on the coil; you may also use shop vac extensions or even pull out coil cleaner in some cases. If you use coil cleaner, be sure to protect components from the cleaner. When doing maintenance on a small refrigeration system, try to prepare for the cleaning ahead of time.

Drain cleaning and maintenance on small refrigeration systems is quite similar to other commercial systems. Drain backups are also a major cause of callbacks. It would also be wise to check that your drain pan heaters are working. You may have to use hot water in low-temp applications, as moisture may freeze on the coil. If you can't use hot water, you may consider using blower fans to avoid freezing (or just letting the unit defrost if you can).

Different climate zones have unique issues. For example, in Florida, we tend to have issues with voltage from the utility companies and constant heat. So, we need to test capacitors because they fail quite often.

Overall, the philosophy of good maintenance is to "do no harm." Astute observation skills are also very helpful when you do maintenance, as you'll be checking many components.

Eric and Bryan also discuss:

Ambient temperature ratings
Radiant heat in grocery settings
Using compressed nitrogen for cleaning
Food prep areas
"Dry" steam cleaning
What if the box is not meeting temp?
Cutting bleed resistors
Unnecessary maintenance procedures

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

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