HVAC School - For Techs, By Techs

In this short episode, Bryan covers traps, vents, and drains. He explains some common misconceptions and best practices for fabricating drains, especially in residential and light commercial structures in Florida.

Cleanouts and vents are commonly confused with each other, and people often cap vents and leave cleanouts open. However, cleanouts (which must be capped) will always be before the trap, and vents come after the trap. When you have an indoor air handler, furnace, or fan coil, vents must be higher than the drain pan to allow the float switch to trip when the drain backs up. (Rooftop units have shorter vents.) Vents should stay open. We use static pressure to determine the trap depth, and the trap outlet must be shorter than the inlet.

The best practice for drain pitch is to have 1/4" of fall for every foot of horizontal run, and we must avoid making double traps where air can get trapped between them. Vents prevent air bubbles from forming in drains with multiple traps. Double traps often form when drains are not supported properly and sag over time; using proper support in your installations is the best way to prevent that from happening.

In Florida, we often use only one trap and still get drainage. A typical installation has a cleanout, a trap, and a vent higher than the drain pan, all on a downward pitch. However, we also get severe condensation on our drains, and we must insulate the horizontal PVC runs to prevent sweating. In multi-family applications with common drains, each individual needs a trap and then a vent before the main drain.

Learn more about the 5th Annual HVACR Training Symposium at https://hvacrschool.com/Symposium24.

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HAVEN IAQ founder and CEO Kevin Hart returns to the podcast to discuss cracking the home health comfort code, diving into IAQ's illusory ideals.

Even though the industry has been generating well-thought solutions to common problems, it's difficult to put those solutions into practice on a large scale. As a result, it's common to rely on selling "bolt-on" IAQ products, which don't actually solve systemic IAQ problems. HAVEN's recent work has also shown that only a few HVAC technicians are proactively offering IAQ solutions to homeowners; the vast majority wait for the owner to ask about a solution instead.

Some IAQ issues stem from duct and building envelope leakage, meaning technicians could offer to perform diagnostic tests (like blower door testing) and address the solution holistically with building envelope and duct sealing. However, not all customers are willing to pay for these, which is one of the biggest challenges of comfort consultations. The question about the real long-term, widespread effectiveness of comfort consults remains to be answered.

Right now, we only have the illusion that IAQ problems are being solved. We might see positive changes to the state of IAQ if there is more forethought on the technician's part to include diagnostic tests in their quotes when it makes sense to do so. Our industry may also see more proactivity in the quest to solve IAQ problems holistically by establishing sales goals and approaches.

Kevin and Bryan also cover:

• Latest HAVEN IAQ developments

• The IAQ status quo

• Technicians and sales

• Evolution of evacuation best practices in the field

• Proactivity vs. reactivity when addressing IAQ problems

• IAQ solution goals and approaches

• The value of commissioning reports

• DIY and consumer-based IAQ solutions

• "Getting in the reps" when using diagnostic tools to solve problems

• The benefits and challenges of selling diagnostic services

Learn more about HAVEN at https://haveniaq.com/ or become a HAVEN Pro today at https://pro.haveniaq.com/. You can also contact Kevin directly at [email protected].

Learn more about the 5th Annual HVACR Training Symposium at https://hvacrschool.com/Symposium24.

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.

In this short podcast episode, Bryan goes over a few tubing insulation tips. Tubing insulation is also commonly known as Aeroflex, Armaflex, and Thermaflex—all brand names for black copper line set insulation.

We typically have to insulate just the suction line in typical residential split HVAC systems, but you'll typically have to insulate both lines in ductless/VRV/VRF or refrigeration applications. The insulation should be on the tubing before brazing, gluing the ends together (only using a specialty tubing insulation adhesive, NOT duct tape!). Since these adhesives are types of contact cement, you will need to apply a thin coating on each side of the joint and wait for a few minutes before pushing the ends together. Some forms of tubing insulation are split and have an adhesive flap instead.

Then, you'll want to hold the insulation back with a clamp about 8-10" away from the area where you're brazing to protect it from heat damage. When you finish brazing, you'll want to put the insulation back and make sure all necessary areas are covered. In cases where it's practical, especially in residential HVAC, pulling the insulation over the 90s and P-traps may be the best bet due to its smaller margins for error. However, mitered fittings may be required in larger systems.

To assemble mitered fittings, use either a miter box or the template on the tubing insulation box. It's a good idea to use the disconnected tubing and make a mitered fitting on the bench as a template before making more—the tails can be a little long. Do NOT use the saw that comes with the miter kit—you will be fine with a very sharp knife that makes a smooth edge (and be safe!).

Learn more about the 5th Annual HVACR Training Symposium at https://hvacrschool.com/Symposium24.

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.

Jim Fultz returns to the podcast to talk about the new HSI module from White-Rodgers, the 50E47U-843. You can learn more about this new universal HSI module at https://hvacrschool.com/hsimodule.

Hot surface ignition modules control the burner for gas appliances that use hot surface ignition, not just furnaces. Since the HSI module doesn't need to work with a blower fan, it can be used in water heaters, pool heaters, and many more appliances that don't primarily move air (except for combustion). It also controls the inducer blower and monitors the pressure switch.

All White-Rodgers universal ignition modules work with the WR Connect app, which allows users to set up controls with a smartphone via NFC technology. The controls do not need to be powered on, and users do not need to be online during use. Users can also use the app to auto-configure their new White-Rodgers controls based on the old control settings. Technicians aren't required to use the app and can configure controls manually if desired.

Universal controls that all operate similarly, like the White-Rodgers ignition modules, are great for creating a consistent workflow and establishing truck stock. In HVAC businesses and in the field, these modules are great for delivering efficiency and quality. The 50E47U-843 also shows real-time flame current, eliminating the need for technicians to wire flame sensors in series with their meter for testing.

Jim and Bryan also cover:

• Emerson, Copeland, and White-Rodgers
• Hot surface ignition vs. other types of ignition
• Integrated furnace controls (IFCs)
• How near-field communication (NFC) technology works
• Fault codes
• Electrical inputs and outputs
• Local vs. remote flame sensing
• Integrated thermostat sensor for infrared and tube heaters
• WR Connect, WR Mobile, and Copeland Mobile apps

Learn more about the 5th Annual HVACR Training Symposium at https://hvacrschool.com/Symposium24.

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.

In this short podcast episode, Bryan talks about locked compressors and hard starts. He explains what actually happens when a compressor locks and covers when and how to use hard starts appropriately.

Locked compressors are compressors that trip on overload during startup; they're considered "locked" because the rotor doesn't turn inside the stator and generates heat instead. The overload opens, but the compressor shell typically does not heat up very much when the overload opens.

When you have a locked compressor, you need to start investigating the root cause with a thorough visual inspection. Then, check the run capacitor. A hard start kit helps you get the equipment working, but we should make sure we've addressed underlying electrical issues or installation conditions before installing a hard start kit. If the unit is old, then we may use a hard start as a temporary solution until the customer can purchase a new unit. In any case, it's best to use a factory hard start if the system requires it, but it's okay to use an aftermarket hard start kit to get an old system to run.

Hard start kits consist of a start capacitor in series with the start winding, which moves more current into the start winding and decreases the time it takes to start the compressor; lower current readings indicate a faster amperage drop, as most ammeters read timed average values. The potential relay needs to open to take the start capacitor out of the circuit so that we don't continuously apply additional current to the start winding, which hurts the compressor over time. The hard start kit is not a silver bullet that solves all problems, and we need to know when to use them and how to use them appropriately.

Learn more about the 5th Annual HVACR Training Symposium at https://hvacrschool.com/Symposium24.

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.

Licensed mechanical engineer Tony Amadio joins the podcast to talk about residential exhaust codes and best practices. He also put together a presentation about the topic, which you can view at https://hvacrschool.com/exhaust.

When choosing duct materials for residential exhaust, you will want to stick to sheet metal and mind the gauge; flex ductwork can easily be damaged and will rack up a high total equivalent length in a way that sheet metal will not.

Exhaust air should always discharge outdoors, not into an attic or crawl space, and that air needs to be replaced by air entering the conditioned space; makeup air is the air we draw in to replace the exhausted air, and we need appropriate undercuts to make sure we're getting the right amount of makeup air.

Domestic cooking exhaust may also come in a few different varieties, each of which has different code requirements (with downdrafts needing much more CFM per ASHRAE). Range hood shape is also important for capturing as many particles as possible, but makeup air kits are usually unnecessary (and could be more of a hassle than they're worth).

When it comes to bathroom exhaust, the CFM requirements differ between residential and light commercial, as well as intermittent and continuous exhaust. Steam generators may also be present, and they require extra consideration.

Tony and Bryan also cover:

• Tony's education and career background
• Discharging and terminating exhaust air
• Insect screens
• Makeup air in light commercial applications
• Clothing dryer vs. bathroom vents
• Ductless clothes dryers and condensate piping
• Home Ventilation Institute (HVI) guidelines
• Pressure imbalance in a structure
• Residential vs. light commercial bathroom exhaust
• Static pressure, blower sizing, and exhaust duct sizing

You can ask Tony questions by email at [email protected].

Learn more about the 5th Annual HVACR Training Symposium at https://hvacrschool.com/Symposium24.

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.

Phil Barr and Nathan Orr join the podcast to talk about wiring refrigerated cases in commercial spaces, including convenience stores and supermarkets.

Cases may be medium-temp (or high-temp, in some cases) or low-temp. Medium-temp cases can typically defrost on their own during the off cycle, and low-temp cases may have electric or hot-gas defrost to help get ice off the coil at set intervals. Each system has an evaporator (and fans), compressor, condenser, and metering device (often a TXV or EEV), and low-temp refrigeration may have anti-sweat heaters, EPRs, and other components to manage.

Challenges arise when electricians don't understand the fundamentals of commercial refrigeration, especially as the electrical circuitry relates to the refrigeration circuit components. Time crunches also apply a lot of pressure to electricians and refrigeration technicians. Testing circuits, such as fans and lighting, or using circuit tracers are good ways to get an idea of how an existing system is wired. Labeling wires and breakers and keeping those labels or information in places where others can read them can help you and other electricians in the future.

One of the most common issues happens when technicians or electricians refuse to test out their results to catch their mistakes before callbacks happen. Even seemingly small electrical issues, such as improper lighting, can cause costly losses if product spoils and cannot be sold.

Phil, Nathan, and Bryan also cover:

• Changes in central and case control strategies over time
• Challenges with retrofits and remodels
• Central lighting controls
• Mistakes that can be made when labeling wires or breakers
• Working against the clock
• Terminal blocks, DIN rails, and connectors
• Making mistakes and the origin of animosity

Learn more about the HVACR Training Symposium or buy a virtual ticket today at https://hvacrschool.com/symposium.

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.

This podcast is a class taught by Bryan: Things to Keep Out of the System. He covers some installation best practices along the way to keep contaminants and non-condensable gases out of the system.

We want to keep air, water, dirt, copper shavings, solvents, and nitrogen out of an operating system. All we want in an operating system is the appropriate oil and refrigerant for the system. Unfortunately, the POE and PVE oil we mostly use in residential systems nowadays are very hygroscopic; they attract water, and POE mixes with water to form acid, another thing we want to keep out of the system.

We can pull most of the moisture out of the system by pulling a deep vacuum and following the best practices for a fast and deep evacuation. However, we can also reduce the probability of moisture getting into the system in the first place by NOT working on copper while it's raining outside, sealing the copper tubing adequately when routing it underground or in a chase (a common installation practice in Florida), and insulating it properly.

Dirt can easily get into the system when we're modifying piping, especially when adding fittings or reaming, but we can use nitrogen or line set cleaners to flush it out. Purging the lines and flowing nitrogen while brazing also help keep air and water vapor out of the copper lines. When deburring, try to avoid letting the burr or copper shavings from falling into the tubing.

Bryan also covers:

• Drawbacks to running copper underground
• Oil return and miscibility with refrigerant
• Flowing nitrogen without a regulator
• Leak detection and nitrogen pressure testing
• Why we should ream or deburr copper to prevent leaks
• Being able to trust your equipment

Learn more about the HVACR Training Symposium or buy a virtual ticket today at https://hvacrschool.com/symposium.

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.

In this short podcast, Bryan talks about air changes per hour, also known as ACH, and what it means in HVAC design and indoor air quality (IAQ) discussions.

ACH tells us how frequently the entire volume of air in a room or structure is replaced; we are referring to the cubic feet of air leaving a space and then being replaced within that same space. If we have a balanced number of cubic feet per minute (CFM) of air supplied to and returned from the room in one hour, we would multiply that CFM by 60 to get the ACH, as there are 60 minutes in one hour. ACH should not be used to calculate heat loss and heat gain, even though BTUs are moved with air.

ACH is a practical guideline for HVAC design. Ventilation needs will vary based on the purpose of a room and the number of occupants in it, and ACH tends to be a more important factor for determining how we can meet ventilation needs in commercial and industrial structures than in residential structures, in which we mostly rely on Manual J calculations of sensible and latent BTU gains and losses. However, we should not confuse ACH with outdoor air ventilation requirements as described in ASHRAE Standards 62.1 and 62.2.

ACH also comes into play when it comes to infiltration and the tightness of an entire structure. When used in the context of blower door testing, the ACH will tell us if a building meets tightness standards. There is also a term called ACH50, which refers to air changes per hour at the standard pressure for blower door testing: -50 Pascals. ACH50 does not reflect ACH under natural conditions (ACH natural).

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Check out our handy calculators HERE.

Roman Baugh joins the podcast to talk about oil return and the refrigerant charge in VRV systems.

VRV systems—also known as variable refrigerant volume (or variable refrigerant flow/VRF) systems—have one outdoor unit, one or multiple compressors, and multiple indoor units. The outdoor unit modulates to meet the indoor units' fluctuating demands. They are versatile and flexible systems.

Like parallel racks, VRV systems have long lines and a lot of piping, so oil return and refrigerant charge are especially critical. VRVs have specific control protocols, as they need refrigerant volume and velocity to move oil and keep it lubricating the compressor for its entire lifespan; oil return mode, the refrigerant charge, and the piping protocols are supposed to support that function.

When it comes to piping protocols, line sizing is critical. Whenever there is a need to relocate the outdoor unit and change the piping configuration, the charge needs to be adjusted, and the piping may even need to be upsized to prevent restrictions from happening. Daikin has VRV WebXpress (and SplitXpress) software for equipment selection; the goal is to help installers out with the line length and charging whenever it needs to be changed.

When trying to get the oil return and line sizing right, you ultimately need to look at the manufacturer's literature and resources. It also helps service technicians if the installer makes the charge and line information readily available to anyone who works on their VRV install in the future.

Roman and Bryan also discuss:

• Where and how oil can settle in VRVs

• Consequences of improper charge in VRVs

• Liquid lines in VRVs

• Violating piping rules and safety protocols

• Vertical separation in liquid line sizing

• Suction line sizing

• POE and PVE oil miscibility

• Daikin's resources

Check out daikincity.com to find Daikin's literature and software programs.

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.