Mar 2021
Relays and Contactors: Part 2
Impedance relays are also called lock-out relays, reset relays, and anti-short cycle controls. All of these terms refer to the same device and the same function. Figure 5-15 shows a typical lock-out relay circuit.
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Mar 2021
Troubleshooting: Too Hot to Handle
I had a call for a routine furnace inspection. The customer said “It’s just a furnace check-up, everything is fine. “This is a 1,400-sq-ft, three bedroom house with a 75,000-Btuh 80% furnace and a 3-ton A/C. Maybe a little oversized for the San Antonio, TX area, but in the ballpark.
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Mar 2021
Last Word: HVACR to the Rescue
The world has changed quite a lot in a year. You don’t need me to tell you this, you already know it. COVID-19 may have been the cause but we are just now starting to see the long-term effects of the virus on the HVACR community.
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Mar 2021
Leading Off: Invest in Yourself
Today it is even more important to keep up with the changes in the industry. Efficiencies are increasing so we need to keep up with the technologies that accomplish that. We are seeing hydrocarbon and A2L refrigerants. There is a lot of wireless technology and home connected devices.
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Feb 2021
Proper Procedures for Brazing Pipe and Tubing
Brazing is an integral part of installing and repairing HVAC/R systems. This metal joining process utilizes a filler metal that melts above 840°F/450°C and below the melting point of the base metals.
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Feb 2021
Field Modifications of Fire, Smoke, and Combination Fire/Smoke Dampers
From the simple extension of a damper sleeve to the replacement of a damper actuator, common changes that may be needed for a factory-supplied life-safety damper to be installed properly.
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Feb 2021
Part 2: The Equal Friction Method of Duct Sizing
This two-part feature on duct sizing is housed in the RSES Service Application Manual collection. Part 2 concludes the “equal friction method” of duct sizing by exploring the meaning of corrected pressure drop tables and friction loss charts.
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Feb 2021
Part 1: Relays & Contactors
Circuit control, in its simplest form, is the application and removal of power. This can also be expressed as turning a circuit on and off, or opening and closing a circuit. Circuit control devices come in many different shapes and sizes, but most are categorized as switches, solenoids or relays.
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Feb 2021
Leading Off: Trust Your Sources
Is the internet a good thing or a bad thing? My answer is both. There is a lot of good information that can be found on your cell phone, your tablet, or your computer. Unfortunately, not all of that information is correct. Anyone can post information on the internet or one of the social media sites, and it might be correct, or it could be completely false.
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Feb 2021
Last Word: Perspective and Balance
Do you ever get the sense that the world and the people in it are simultaneously moving faster and slower at the same time? It is an interesting phenomenon to observe, and I am airing my opinion here about it because it is relevant to our time.
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