In this short Q&A podcast episode, Bryan answers a listener-submitted question about superheat, including what it is and how we measure it.

Superheat is the number of degrees a refrigerant is above its saturation point. The saturation point is where you will have a liquid-vapor mix, so superheat only exists when a substance is a vapor. Saturated refrigerant should only exist in the evaporator and condenser, during which it is being boiled or condensed.

We usually measure superheat at the evaporator coil outlet and compressor inlet. The superheat at the evaporator outlet is usually around 5-14 degrees Fahrenheit, and it's often between 10 and 20 degrees at the compressor inlet (compressor superheat). However, many systems try to get lower superheat values, and some manufacturers may require higher superheat values at the compressor inlet to prevent liquid refrigerant from getting into the compressor. Accumulators can help keep liquid refrigerant out of the system as well. We may also measure superheat coming out of the compressor on the discharge line (discharge superheat); this superheat may exceed 100 degrees Fahrenheit. Discharge superheat can let you know if the compressor is overheating the oil and causing breakdown or carbonization.

We use superheat to set the charge for fixed-orifice metering devices (as opposed to subcooling for TXVs), as superheat is a measure of how well we're feeding our evaporator coil. When the system is off, the superheat will be 0. A system will equalize, and the refrigerant will be at saturation when that happens.

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool.

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In this episode of the HVAC School podcast, Bryan interviews Zach from Southeast Clean Air Solutions about the intricacies of professional duct cleaning. Zach specializes in addressing duct cleaning challenges specific to the Southeastern climate, with a particular focus on fiberglass-lined ducts. The conversation delves into the complexities of cleaning different types of duct systems, highlighting the significant variations in time, technique, and approach depending on the duct materials and home configuration.

The discussion reveals that duct cleaning is far more nuanced than many homeowners realize. A typical residential duct cleaning can take between six to eight hours, with metal ductwork being significantly faster to clean than flexible ducts or fiberglass-lined systems. Zach emphasizes the importance of careful cleaning techniques, especially with delicate flex ducts that can easily be punctured or damaged during the cleaning process. He recommends a two-person approach, with one team member working inside the home and another in the attic or crawl space to ensure thorough and safe cleaning.

Beyond the cleaning process, the podcast explores critical maintenance strategies for maintaining clean and efficient HVAC systems. Zach and Bryan discuss the importance of proper filtration, home maintenance, and understanding when duct cleaning is truly necessary. They challenge the common misconception of a fixed cleaning schedule, instead advocating for system assessment based on specific conditions like household dust, humidity, and the health needs of home occupants.

Key Topics Covered:

• Duct cleaning techniques for different duct materials (metal, flexible, fiberglass-lined)
• Time requirements for professional duct cleaning
• Challenges of cleaning ducts in various home configurations
• Importance of proper filtration and maintenance
• Factors determining duct cleaning frequency
• Risks associated with poorly maintained duct systems
• Two-person approach to thorough and safe duct cleaning
• Specialized considerations for homes in humid climates
• Post-cleaning sealant application for fiberglass-lined ducts

Learn more about NADCA and find certified duct cleaning contractors at https://nadca.com/.

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool.

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In this short podcast, Bryan talks about electric vehicles and whether EVs present an opportunity for HVAC technicians. The residential sales lead at Kalos recently mentioned that keeping an EV in a conditioned garage is advantageous, and it's an upgrade we can offer our customers.

In hot weather, EV battery performance and health can be degraded. On top of that, the vehicle consumes power when the vehicle gets hot so that the A/C can control the climate inside the car and preserve the interior. Most people also charge their electric vehicles in the garage at night, so it would stand to reason that conditioning the garage can yield energy savings and improve vehicle longevity. Attic encapsulation above the garage is also an option to limit warm, moist attic air from leaking into the garage; HVAC upgrades can include using closed-cell foam to encapsulate the attic and install a dehumidifier in there.

Conditioning a garage requires you to think about insulation. In our market (Florida), block walls don't insulate very well. Even when we can't do very much with the walls, we can usually use some polyiso boards inside the garage. However, we could get some moisture challenges, and carbon monoxide could be an issue if combustion appliances are in the garage (like furnaces, water heaters, or gas-powered cars). We can recommend using heat pump water heaters, and we should quote a low-level CO monitor in cases when garages have a CO risk.

It's important to make sure the garage remains separate from the rest of the house even when we do these upgrades. Keeping the garage separate helps prevent chemicals from getting into the airstream, especially yard chemicals or cleaners.

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool.

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The podcast delves into the world of HVAC chemical solutions through an in-depth conversation with Becca Stamey, the marketing director at Refrigeration Technologies. The discussion provides insights into the company's unique approach to developing cleaning products, rooted in a commitment to safety, effectiveness, and customer feedback. Founded by John Pastorello, a chemist turned HVAC technician, the company has always prioritized creating products that are non-toxic, non-corrosive, and environmentally friendly.

Becca highlights the range of Viper products, from condenser and evaporator cleaners to pan and drain sprays and all-purpose cleaners. Each product is carefully formulated with specific purposes in mind, such as the enzyme-based evaporator cleaner designed to address odor issues and break down biofilm. The conversation emphasizes the company's innovative packaging, particularly the Venom Packs, which offer concentrated, durable, and space-efficient solutions for technicians. The podcast also underscores the company's commitment to quality control, with U.S. manufacturing and personal oversight from the leadership team.

The episode provides a behind-the-scenes look at Refrigeration Technologies' growth and dedication to the HVAC community. The company has been named to the Inc. 5000 list of top-growing companies for three consecutive years and is expanding its manufacturing capabilities. Becca discusses the company's social media presence and community engagement, including their "Tech of the Month" program, which highlights and celebrates HVAC technicians who embody the company's values.

Key Topics Covered:

• Viper's chemical product line and unique formulations
• Condenser and evaporator cleaning solutions
• Innovative Venom Pack packaging
• Importance of non-toxic, environmentally friendly cleaning products
• Company's manufacturing process and quality control
• Social media engagement and community recognition
• Recent company growth and expansion
• Upcoming appearances at industry events like AHR Expo

Learn more about Refrigeration Technologies at https://www.refrigtech.com/. You can also follow Refrigeration Technologies on Instagram, LinkedIn, Facebook, YouTube, and TikTok (ViperHVAC).

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool.

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In this short podcast, Bryan talks about evaporator coil placement based on a question submitted by a listener, John. Evap coil placement differs in furnace applications versus air handlers.

When we use air conditioners with furnaces, we usually put evaporator coils on the positive side to protect the heat exchanger from rusting out during the summer (due to condensation and the chemical reactions that can occur with the metal heat exchanger). However, when it comes to air handlers, they're usually on the negative side. The coil is usually on the negative side of a fan coil or air handler because it keeps the blower motor cooler (though that doesn't make a huge difference in terms of performance).

The HVAC system will lose fewer BTUs to leakage when the coil is on the negative side, which is better for energy efficiency; those BTUs can reach the conditioned space rather than the closet, garage, or wherever it is stored. Pulling air over the evaporator coil on the negative side, however, could potentially lead to greater turbulence.

We run into challenges with evap coil placement on gas furnaces when we have dual fuel systems (a heat pump and furnace working together). You can't run gas heat over a heat pump coil due to the high head pressure, so a parallel setup would avoid the risks of high head pressure (downstream) or rusted-out heat exchangers (upstream).

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool.

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In this episode of the HVAC School Podcast, Bryan interviews Zachary Ortwine, a duct cleaning professional who provides insights into ethical duct cleaning practices. The conversation delves deep into the complexities of cleaning different types of ductwork, the importance of proper assessment, and the potential challenges in maintaining indoor air quality.

Zach emphasizes the critical role of thorough inspection and honest communication with clients. He explains that not all duct systems are equally cleanable, and professionals must carefully assess factors like duct material, contaminant type, and cleaning feasibility. Metal ducts can be cleaned more aggressively, while fiberglass ducts require a more delicate approach. The discussion highlights the importance of understanding the underlying issues that contribute to indoor air quality problems, such as system design, maintenance, and home living conditions.

The podcast explores the evolution of duct cleaning technologies and safety considerations. Zach shares insights into modern fiberglass materials, which have improved safety compared to older versions, and discusses the importance of proper cleaning and coating techniques. The conversation also touches on broader indoor air quality challenges, including the impact of tighter building envelopes, ventilation issues, and the potential health risks of prolonged exposure to indoor contaminants.

Key Topics Covered:

• Ethical considerations in duct cleaning
• Assessment techniques for determining cleanability
• Different duct materials (metal, flex, fiberglass) and cleaning approaches
• Indoor air quality challenges in modern homes
• NADCA (National Air Duct Cleaners Association) standards
• Importance of technician certification and experience
• Ventilation and its impact on indoor air quality
• Proper testing and verification of cleaning results
• Coating techniques for fiberglass ducts
• Misconceptions about antimicrobial treatments

Learn more about NADCA and certified professionals at https://nadca.com/.

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool.

Purchase your tickets or learn more about the 6th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

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In this short podcast episode, Zach joins Bryan to answer a common duct maintenance question: Should I fog or sanitize my ducts?

The National Air Duct Cleaners Association (NADCA) outlines the uses of chemical products. Adding chemicals is usually a last resort in flex or sheet metal (externally wrapped) duct systems; they should NOT be used on ducts with internal liners or are made of duct board or any other material with porous surfaces.

Fog is typically applied while a vacuum is running at the opposite end of the duct. It liquefies on surfaces, and a lot of contractors don't go in and dry off the duct surfaces. It's difficult to coat the entire interior of a duct system with the chemical to make it as effective as possible, and the residue creates a moist, sticky film that actually encourages microbial growth in the ductwork. On top of that, some people may be sensitive to the chemicals.

In many cases, replacing ductwork that has been confirmed to have microbial growth is more reliable. Chemical duct sanitation often has more of a perceived benefit than long-term results. The use of chemical cleaners in ductwork is similar to that of using some line set flushes without forcing a solid pig through the line set to pick up the residue afterward. Ultimately, the customer has to make an informed decision based on the problem and knowledge of the benefits and drawbacks of chemical solutions.

NADCA's white papers, including "Chemical Product Applications in HVAC Systems," are available at https://nadca.com/industry-professionals/nadca-white-papers.

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool.

Purchase your tickets or learn more about the 6th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

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Check out our handy calculators here or on the HVAC School Mobile App for Apple and Android.