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Tech Tips:

There are three types of floors: slab-on-grade, crawlspace, and basement. It should be fairly obvious when you are collecting field data as to what type of floor you are working with. Here is a brief overview of how each type affects a load calculation. Much of the information for this article comes from Allison Bailes’s […]

Powered Attic Ventilation

When I first started in the trade, I used to advise customers with hot attics to install powered attic ventilators (PAVs) to “suck” that hot air out of the attic. It just made sense to me at the time; if the attic is hot, get the hot out! When I started learning more about design, […]

The Hidden Cost of Killing Radiant Load – Short #260

In this short podcast, Bryan talks about the hidden cost of killing radiant load, especially when it comes to installing radiant barriers in attics. We sometimes get service calls about ducts sweating when they never used to sweat. If there are no problems with the system (i.e., the refrigerant charge, static pressure, airflow, supply […]

Are EVs an Opportunity? – Short #222

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 […]

Igor Pontes
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HVAC School – For Techs, By Techs

Real training for HVAC ( Heating, Ventilation, Air Conditioning and Refrigeration) Technicians. Including recorded tech training, interviews, diagnostics and general conversations about the trade.

In this spooky Halloween short podcast episode, Bryan tells the story of the cooling tower killer: Legionnaires’ disease.

In the summer of 1976, the nation celebrated its bicentennial anniversary. The American Legion was holding its 58th annual convention at the Bellevue Stratford Hotel in Philadelphia, PA. In the days following the convention, doctors in Philadelphia started noticing dozens of Legionnaires in their hospitals with high fevers, chills, coughs, and difficulty breathing. Their symptoms resembled those of pneumonia, but patients deteriorated quickly, and antibiotics didn’t work as expected. People became more ill, and 34 of them died. There were many theories, from food poisoning to novel viruses to bioterrorist attacks.

The CDC investigated biological samples from patients and swabs from the hotel alike, but their findings were inconclusive. As news outlets sensationalized speculation over the cause of the illnesses, the disease was named after the unfortunate Legionnaires who suffered from it. However, the speculation would come to a close months later when CDC scientist Joseph McDade reviewed the samples and found a tiny, round-shaped bacterium living in the lung tissue of the victims. The bacteria would be named Legionella pneumophila.

Investigators traced the bacteria back to the hotel’s cooling towers. Cooling towers are essentially giant evaporative coolers and can create a mist. Legionella can thrive in the warm water of cooling towers, and the cooling towers dispersed the mist throughout the area, making hundreds ill. When water stagnates, bacteria can fester, but temperature is just as important as movement. As contractors, our maintenance procedures can save lives. In cooling towers, that maintenance entails regular cleaning, chemical treatment, and monitoring water temperature and flow.

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Legionnaires’ Disease: The Cooling Tower Killer – Halloween Short #263

10/28/2025

Bryan Orr

Group Training – What We Have Learned

10/23/2025

Bryan Orr