HVAC School - For Techs, By Techs

Latest Episodes:

Air Filters, They are More Complex Than You Knew w/ Lee Andrews May 21, 2018

Show notes

In today's podcast episode, Lee Andrews with Andrews Filters talks about the complicated and important topic of air filters and filtration. He also explains why they should matter to you and your customers. As indoor air quality (IAQ) becomes more important in HVAC work, air filters will become even more important than they already are.

We classify air filters by MERV ratings. MERV ratings describe the ability of filters to capture finer particles; a MERV 11 filter will catch a lot more particles than a MERV 6 filter. Most air particulates are an average of 0.4 microns large, but most air filters only catch 5-15% of those particulates. The filter industry aims to catch smaller and smaller particulates to improve indoor air quality, protect equipment, and keep consumers healthier.

However, MERV is not a comprehensive value for efficiency. The actual filter media is also important for a filter's efficiency. Higher-quality, finer fibers will have a higher probability of catching smaller particulates. Having a greater surface area (more pleats) also increases performance. The media has a small charge, which helps a filter collect particles. Humidity, particulate insulation (dirtiness), and alcoholic pollutants (such as diesel) can discharge a filter and reduce efficiency.

Many people use MERV 8 filters, but very few understand the difference between MERV 8 and MERV 8A filters. The addendum of the MERV test (A) uses an alcohol-type product to remove the charge. So, MERV-tested filters without the addendum test can actually perform at a lower-rated level. For example, a MERV 8 filter could perform more like a MERV 5-6 filter.

Bryan and Lee also discuss:

Electrostatic charge and airflow
MERV 8 vs. MERV 8A
Loading and unloading
Board materials
Filter design and sizing
Talking to customers about filters
Energy savings

Check out Andrews Filter's website at andrewsfilter.com.

Check out Refrigeration Technologies' chemical products HERE.

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

How to Repair Aluminum Leaks May 15, 2018

Show notes

Have you ever struggled to repair a leak in an all-aluminum coil? Lance Robinson with SolderWeld talks about his product to do just that and makes a convincing case for aluminum repair.

We've been using aluminum for several decades before the shift to copper; unlike copper, aluminum is corrosion-resistant. However, copper is typically better for brazing due to its heat transfer properties and ductility. If we can get to a point where we can use aluminum for the same uses as copper, we will probably see a shift to aluminum due to its durability.

SolderWeld has recently made an aluminum repair product. Alloy-Sol is a solder, meaning that it works below 840 degrees Fahrenheit, and it gives techs plenty of time to work without worrying about melting the aluminum. Alloy-Sol works with a powdered flux, which goes on in a white paste that bonds to the aluminum and cleans it. When the flux turns clear, you can begin applying the solder to join the surfaces. You can melt the rod into your repair so long as you have that bond. You can use Alloy-Sol to perform COMPLETE aluminum repairs, not just temporary repairs.

When applying heat, make sure you apply heat perpendicularly to the repair. Repairing aluminum requires perhaps a bit more focus and finesse than copper brazing, but it is still a relatively easy process. We may not have considered aluminum repairs in the past, but they are worthwhile with the correct solder products.

Bryan and Lance also discuss:

Aluminum's low melting point
Torch usage and heat application
Working with microchannel coils
Training techs to repair aluminum
Cleaning aluminum
Fittings for aluminum piping
Aluminum repair limitations
Alloy-Sol in the auto body industry
SolderWeld's history

Learn more about SolderWeld HERE and Alloy-Sol 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 #8 - Resistance Up, Amps Down May 14, 2018

Show notes

This short podcast episode covers the most misunderstood portion of Ohm's law explained masterfully from 1921: when resistance goes up, amps go down.

The American Electrician's Handbook (1921) contains a lot of electrical knowledge that holds up in the present day. (The electrical testing methods don't hold up quite as well, though...) One of those principles that hold up is the idea that amps go down as resistance goes up. Amps refer to current (electrons). The ohm is the unit of electrical resistance, and it is NOT the same as mechanical resistance, such as in a compressor with locked-up bearings.

The common "water" analogy for electricity works quite well for helping us see how voltage enters the equation. Electromotive force (EMF) is comparable to water pressure, which pushes water in a hydraulic piping system. So, you can compare voltage to PSI. The current (amps, I) is comparable to the flow of water. So, if you have more pressure inside a hydraulic system, more water will flow out; as voltage (V) increases, amperage also increases. That analogy also explains why you can have volts without amps; there can be plenty of water pressure behind a closed valve, but there will be no flow.

Additionally, a smaller pipe has more resistance than a large one. So, less water (amps, I) will flow through a pipe with greater resistance (ohms, R). When resistance goes up, amps go down; the water analogy illustrates that principle very clearly in terms that we are familiar with.

With all these in mind, you can yield the three following equations that make up Ohm's law:

I = V/R

V = I x R

R = V/I

Learn more about Refrigeration Technologies chemical products HERE.

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

Universal Digital Refrigeration Controls and the Danfoss ERC 213 May 10, 2018

Show notes

In today's podcast episode, Jamie Kitchen talks about refrigeration controls and applications. He also tells us about the Danfoss ERC 213 universal digital controller.

Electronic refrigeration controls tend to have greater accuracy and flexibility than traditional electromechanical controls. These electronic controls also allow you to perform many more tasks than traditional ones. Electromechanical controls also wear out and lose their accuracy over time.

When you deal with applications that require various temperature, humidity, and defrost requirements, you can use electronic controls to choose between several options for the defrost method, defrost stop temperature, fan delay after defrost, etc. You can also put voltage and head pressure protection measures in place. You can optimize defrost and box temperature with electronic controls, but you can't control evaporator coil feeding. However, EEVs work well with these refrigeration controls and can adjust evaporator coil feeding. The ERC 213 has temperature and defrost sensors, but you can also configure it to work with other sensors, if you prefer.

The ERC 213 has seven different application settings (0-6). In cases where a preset option will suffice, choose between Apps 1-5. (Consult Resources for the ERC 213 installation guide, which explains each application.) However, you shouldn't assume that the electronic controls will have the same settings as mechanical controls. If you want to learn the full functionality of the ERC 213, you can use Apps 0 & 6 to customize parameters. Just remember to supply the correct voltage to the controller (120v).

Bryan and Jamie also discuss:

Customizable settings
Superheat controllers and EEVs
How defrost requirements change seasonally
Controlling compressors
Ice machines and restaurant refrigeration equipment

Resources

Find out more at Danfoss.com, and check out the ERC 213 installation guide to learn more about the ERC 213.

Check our Refrigeration Technologies HERE.

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

Manifolds vs. Probes Battle w/ Adolfo Wurts May 08, 2018

Show notes

In this episode, Adolfo Wurts from Arbiter comes on and debates why a tech would want to use a manifold over wireless probes and vice versa.

In our industry, we are likely to see a trend of moving towards wireless equipment that connects to a single device. Wireless connections and digital displays may save us money on tools and allow us to store and interpret data more efficiently. However, a manifold can help you recover refrigerant, whereas probes cannot. Manifolds also have sight glasses, which help you check for overfeeding; probes do not offer you much help on that front. Manifolds can also fit into tight spaces a bit more easily than probes, but probes have already come a long way and will continue to get better.

Manifolds may feel heavier and seem more durable, but wireless probes are actually light yet hardy, and you don't have to worry about cracking screens. Probes and manifolds are probably similarly hardy, but probes are lighter and have fewer components to damage. Probes also have a massive edge over manifolds in the area of contamination prevention.

Using your phone with probes has its advantages and disadvantages. Unfortunately, you expose your phone to situations that may damage it. However, you can access all of your readings in real-time from the phone. Your phone also has more processing power, and some apps can perform advanced calculations. You can avoid exposing your personal phone to field damage by using an older, cheaper phone just for field usage.

So, as our society and industry become more tech-savvy, probes will continue to improve. Probes that have an edge now will still improve, and you may want to consider using probes over manifolds. However, you may want to have additional hoses and a sight glass.

Adolfo and Bryan also discuss:

UEI Hub kits
Tool misuse and damage through improper storage
Software in HVAC/R apps
K-type thermocouples
Using probes in ductwork
Dehumidification

Find out more about the UEI hub kits HERE.

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.

HVAC/R Conductor, Breaker, and Fuse Selection May 07, 2018

Show notes

In this podcast episode, Phil Barr joins Bryan to explain sizing for wires and breakers in HVAC/R work. You will be able to select breakers, conductors, and fuses properly and without confusion. Phil Barr is the leader of the electrical division at our business.

HVAC/R equipment may have hermetically sealed motors. Unlike squirrel-cage motors, hermetically sealed motors have an outer shell that makes it impossible to access the inner components. Semi-hermetic equipment, such as some compressors, look like hermetic equipment but can open up. Wire sizing varies between hermetically and non-hermetically sealed motors, and the NEC explains the wire sizing requirements, but YOU need to know the context for those requirements.

Once you know your equipment type, check the nameplate with a rating, such as MCA, RLC, branch circuit selection, etc. The manufacturer will establish that rating, and you will use it to look up the correct wire sizing requirements. Wire insulation and conductor type also dictate the sizing and installation requirements. Conductor length and voltage drop also affect wire sizing.

Fuses or circuit breakers prevent shorts. Shorts are undesigned paths with little to no resistance, so fuses and circuit breakers protect equipment and buildings from overcurrent due to shorts, NOT thermal overload. So, you use MOCP as a guideline for sizing your breakers. Thermal overload protection keeps conductors from melting under overload conditions.

If you want a breaker that is under the MOCP value but it exceeds the MCA and the terminations are rated correctly, you can typically use a breaker between the MCA and MOCP. However, you will still want to follow manufacturer recommendations and check with your AHJ.

Phil and Bryan also discuss:

MCA (minimum circuit ampacity)
"Undersized" conductors in new constructions
Reducing voltage drop
MOCP and related terms
Inrush current
Adjustment factors

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

Humidity Talk w/ Johnathan Jones May 01, 2018

Show notes

In today's podcast episode, Johnathan Jones from Clean Comfort, Ultra-Aire, and Therma-Stor talks to us about humidity, dehumidification, and ventilation.

Relative humidity (RH) is a moisture content ratio that depends on temperature. Hotter air can hold more moisture, and colder air can contain less moisture. You can increase or decrease the temperature to change the relative humidity, but the dew point stays the same. The safest humidity range is between 40-60%. It is typically harder to add humidity to an arid place than to remove humidity from a tropical place.

We work to control the dew point (keeping it below 55 degrees). When we keep our indoor temperatures well above the dew point, we don't have to deal with condensation and moisture, which leads to microbial growth. We encounter two conflicting schools of thought: reduce the fan speed to control humidity or raise the fan speed to keep the ducts warm enough to prevent "growth." However, a dedicated dehumidifier takes care of the space without requiring fan speed changes.

A lot of indoor moisture comes from our bodies, such as by breathing and talking. Local ventilation, especially during cooking and showering, helps reduce moisture ONLY if it sucks in quality outdoor air. Ventilation strategies can be balanced or imbalanced. Balanced ventilation helps us avoid negative ventilation; mechanical ventilation brings the building under positive pressure. When a building is under positive pressure, air gets pushed out to maintain balance. Additionally, pollutants tend to stay out. However, positive pressure can cause condensation to occur in colder climates and works best alongside a dehumidifier.

We also discuss:

Moisture units (pints, pounds, grains)
Infiltration
Encapsulated attics
ERVs in coastal states
Ventilating dehumidifier setup
Comfort differences based on humidity alone
Latent and sensible capacity
Hot gas reheat applications
Dehumidifiers and energy efficiency

Check out Clean Comfort HERE, and check out Therma-Stor HERE.

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

Check out Refrigeration Technologies HERE.

Short #7 - A Moisture Problem Apr 27, 2018

Show notes

In this short episode, we replace a dirty "M" word (mold) with another "M" word (moisture) that gets to the root of the problem.

"Mold" and "mildew" can freak out your customers. For years, I've refrained from saying "mold" at my own company and trained my techs to avoid it AND "mildew." Instead, we have called it "biological growth" or "organic growth." Those still aren't great. Just recently, my friend Joe Medosh suggested referring to fungal growth as a "moisture problem" instead.

"Moisture problem" is a fact-based and less disgusting term. We can focus on solutions with indoor air quality (IAQ) to address the overarching issue that causes the growth, not just the nasty growth.

In some cases, parts of the home may hit the dew point in colder temperatures. So, drywall is particularly vulnerable to falling to dew point if the building envelope has been poorly sealed. So, we have a practical means of reducing relative humidity below 55%. We can also seal the envelope better and address potential issues related to infiltration.

A duct with poor or compressed insulation may also be prone to "moisture problems." We can address those "moisture problems" by properly strapping the duct. In cases when air handlers sweat by an improperly sealed duct, we seal the duct correctly to nip the problem in the bud. In the case of sweating vents, we must analyze the supply air, check the blower fan speed, and look for restrictions. Make sure all components are clean and that you seal up any leaky areas.

Remember, "moisture problems" do NOT occur because hot meets cold! The moisture content and dew point are the key factors, not just a temperature differential.

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

Prevent Compressor Murder Part 2 w/ Emerson Apr 24, 2018

Show notes

Here is part 2 of the discussion with Trevor Matthews about the causes and prevention of air conditioning and refrigeration compressor failure.

Slugging occurs when the compressor attempts to compress oil or liquid refrigerant. A telltale sign of slugging is valve plate damage. On a semi-hermetic compressor, you can remove the screws on the head to access the valve plate. Wrist pin wear occurs during slugging the wrist pin is between the rod and the piston; you should test the wrist pin to see if it makes a knocking sound before you dismiss all other possibilities and replace the valve plate.

Overheating occurs when there is a system-related issue. Compression ratio is an indicator of overheating, but few technicians check it often enough. A requirement for external cooling and dirty condenser coils can cause overheating. Overheating also causes oil issues; when a compressor gets too hot, oil breaks down and loses its ability to lubricate the bearings.

Oil loss is a tricky cause for failure; it is hard to notice without a sight glass. Short-cycling can lead to oil loss over time, and bearings will begin to wear when there isn't enough oil to lubricate them.

Contamination usually occurs when moisture corrodes the copper plating and introduces acid to the system. Acid and sludge are the most common contaminants. Proper reaming practices also keep copper out of the system and reduce the risk of acid contamination.

Trevor also discusses:

Slugging in scroll compressors
Sight glasses and oil measurement
System load and suction pressure
Maintaining design compression ratio
"Blow by"
Oil separators
Replacing line dryers
Components to troubleshoot and inspect

Verifying System Operation Sheet from Emerson http://hvacrschool.com/Emerson

Verify Diagnosing Compressor Failures from Emerson http://hvacrschool.com/CompFailures

Short #6 - Energy? Compared to What? EP1 Apr 20, 2018

Show notes

In this short podcast, we start the conversation about "Energy? Compared to What?" and explore several energy comparison examples.

When we think about energy, we can confuse some terms. For example, temperature and heat are related but NOT synonymous. Temperature is an average measurement of heat energy; when many molecules move at a bunch of different speeds, the temperature represents the average speed of those molecules. Temperature does NOT measure total heat content. Voltage and amperage are two more confusing terms, and they get even harder to understand and differentiate when you throw "power" around.

In most diagnostic cases, we usually measure things to compare them, such as using a voltmeter to measure a difference in electrical charges. We could compare the usage of a voltmeter to a temperature difference between two rooms. The wall between the rooms presents resistance between the temperatures of the two rooms (R-value, which affects energy transfer), and the voltage is analogous to the potential difference between the rooms.

In the HVAC industry, we can witness energy differentials in temperature, charges, and pressure. Resistance gets in the way of these differentials reaching equilibrium and must be accounted for in our readings. Resistance affects the rate of energy transfer; that resistance can show up as friction, R-value, and other values that affect the total amount of energy transferred.

Many techs also go wrong when they assume that a 120V blower motor draws twice as many amps as a 240V blower motor. In truth, the 240V blower requires twice as many amps to hit the same work target. In a 240V motor at 120V, it would draw far less amperage and result in less than half the usual horsepower.

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

Our TOPPODCAST Picks

Follow Us

Stay Connected

HVAC School – For Techs, By Techs

Related Podcasts

Links

Stay Connected