Comments by "alex smith" (@alexsmith-ob3lu) on "" video.

I work as a journeyman electrician doing new construction work for residential-commercial properties. It’s interesting to see how the HVAC systems and fire alarms have changed over the years. I remember my old man telling me that back then, HVAC was all based on pneumatic controls. Now it’s all electronic systems. There were hardly any fire alarms used back then (aside from water sprinklers), but now we’ve got smoke detectors on each floor.
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@markgarland9000 For large buildings such as the Chrysler and Empire State buildings; those types of buildings utilized mechanical pneumatics (later on electro-pneumatic by the 1950s) to control and bring heated or cooled air into a given space. I’ve worked on old school buildings (and other various institutions) built back in the 1920s and 50s. Old schools from the 1920s only have manually controlled radiators for heating. While schools built in the 50s had dedicated mechanical rooms using air compressors to control temperature/humidity for the classrooms. I was stunned by the complicated pneumatic thermostats, quarter inch copper piping, and pneumatic actuators (control valves) that were designed, built and installed! It’s amazing how we lost so much old wisdom in recent decades!
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@markgarland9000 Wow, I did not know that… I always thought we got the monster sized window AC’s in the 1980s or 1990s. Thanks for telling me! It seems to me that before WW2, we had the the right HVAC controls for medium and high density buildings, but little for low density buildings. Nowadays, we have all the right HVAC tools for low density buildings, but we’re terribly lacking with how HVAC controls works for larger buildings…
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