#hvac

We’ve talked about compression ratio a lot over the years. Compression ratio is the number you get when you divide the absolute head pressure (PSIG + 14.7) by the absolute suction pressure (PSIG + 14.7). It measures the efficiency of a compressor, and lower numbers indicate that the compressor is moving more refrigerant while consuming […]

If you own your HVAC company or are involved in management, you may have realized that our industry is currently facing a shortage of new A2L refrigerants, particularly R-454B and R-32.  Our own company has faced limited availability and long lead times, mainly due to supply chain disruptions and the increased demand now that our […]

I want to share something that came up in a recent discussion with Roman Baugh about VRF systems, and it made me realize I might have had a blind spot regarding scroll compressor designs. We were talking specifics, and he brought up high-pressure shell compressors. My immediate thought was, “Hold on, aren't scrolls low-pressure shell […]

There are three things we never discuss at the dinner table: religion, politics, and which wire to break with your float switch. A float switch fills with water whenever there is a drain backup, and it breaks power to one of the low-voltage wires. We clearly want the HVAC system to stop producing more condensate, […]

Being in an industry that requires a lot of travel—local or regional—can be a great thing for people who enjoy driving. It also comes with several more risks and opportunities for roadway accidents than someone who just has a round-trip commute to a single location every day.  We’re all aware of the issues of texting […]

A few times in the past, we’ve heard the phrase “the house is the biggest duct” because of the way air moves through it. Well, we can take it a step further and see that there are similarities that go just beyond air movement.  A building has several layers to keep things like moisture, heat, […]

Delta T is the difference in temperature between two points of the same medium. It is commonly used by scientists and engineers to analyze the amount of heat transfer in a system. In general HVAC terms, it is the measurable change in temperature between an air input and air output. However, it could also be […]

DISCLAIMER: HVAC School is NOT an official OSHA safety training resource! Although we provide safety tips in good faith, our website is not a substitute for safety training from an authorized OSHA training source. Many things may deter people from working in the HVAC industry. Perhaps surprisingly, exposure to heights could be the deal-breaker. (Not […]

This tech tip comes from a post in the HVAC School Facebook group by Ed Janowiak. Ed is the Manager of HVAC Design Education at ACCA, a longtime friend of HVAC School, and an educator who does a lot of great work for the industry. Thanks, Ed! This past Thursday, I taught a class where […]

 In this engaging session, David Richardson breaks down the concept of high-performance HVAC, offering a clear roadmap for industry professionals looking to elevate their craft. Richardson argues that the HVAC industry has long been focused on equipment rather than complete systems, leading to widespread inefficiencies. The average system delivers only about 57% of its […]

 In this short podcast, Bryan answers a listener-submitted question about Nylog, oil, and where you put them when you're making flares. Nylog is a thickened refrigerant oil (which is either POE for Nylog Blue or mineral oil for Nylog Red), and it's miscible with the refrigerant and moves with it through the circuit. You […]

 In this episode of the HVAC School podcast, Bryan and Jim discuss strategies for growing an HVAC business, focusing on the importance of maintenance contracts, consistent service, and effective branding. Drawing from Jim's 15 years of experience running a successful HVAC company in California, they explore how maintenance contracts not only provide consistent revenue […]

 In this short podcast episode, Bryan answers a listener-submitted question about oversized evaporator coils, particularly when they're half a ton or a full ton larger than the condenser. The expanded performance data contains the information that'll tell you whether the coil is right for the system. However, when it comes to the specific issue […]

 In this episode of the HVAC School podcast, host Bryan sits down with building science expert Allison Bailes to dive deep into the world of Energy Recovery Ventilators (ERVs). The conversation explores the critical role of ventilation in modern homes, highlighting how ERVs have become an essential component of maintaining indoor air quality and […]

 In this short podcast episode, Bryan answers a listener-submitted question asking whether you can use another surge protector at the disconnect panel with an ICM 493 already in place. Using multiple surge protectors in the configuration described does NOT count as daisy-chaining. Surge protectors with MOVs (metal oxide varistors) shunt current from high voltage […]

 In this podcast episode, HVAC professionals Chris Hughes and Adam Mufich discuss the intricate challenges technicians face when commissioning modern inverter-based heating and cooling systems. Unlike traditional single-stage or two-stage HVAC equipment, inverter systems introduce a new level of complexity that can leave even experienced technicians feeling uncertain about proper installation and startup procedures. […]

 In this short podcast episode, Roman Baugh takes over the HVAC School podcast to answer a listener-submitted question about VRF (or VRV) system evacuation. Evacuation is a critical step of making repairs on VRF systems, which are very diverse and versatile but require a high level of understanding. VRF systems have multiple indoor units […]

 This podcast episode is of Bryan's session from the HVAC School Symposium, “10 Things I've Learned in the Last 10 Years.” Delivered as HVAC School approaches its 10-year milestone and Kalos hits 20 years, Bryan blends technical know-how with personal stories, revealing how his “expertise” is a product of constant learning—often from the very […]