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How an A/C System got to be Oversized (Maybe) But My Old Unit Worked Fine?! Most of us have heard this at some point. This complaint typically comes from a particularly unhappy customer after the installation of a brand new A/C system. Throughout this article, we’re going to explore the possible root causes of this […]

Comparing Manual J to Reality

This article was written by HVAC contractor and Building Science Whiz, Michael Housh. Thanks, Michael! For a while, I’ve fallen into this camp where I feel Manual J overshoots heating loads. First off, I would like to say that Manual J is only as good as the information you give it, but we often run […]

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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