Recently, a much younger engineer than I asked if we could meet and discuss an energy retrofit project she was working on but was not familiar with the application. The existing HVAC exhaust system served lab exhaust and the system was a vane axial, controllable-pitch fan with a discharge duct extending straight up 10 ft above the roof.

Her question was, “What was the design engineer thinking back in 1974?” No variable exhaust with induced outdoor air to maintain a constant exhaust velocity! After our conversation I began writing down forgotten terms and antiquated technology. Note, as I continue herein I’m leaving out the acronyms’ meanings just for the fun of it. It will be up to you to “Google” their meanings beginning with EDR.

  • EDR was a rating used up until probably the end of the 1960s and pertained to baseboard radiators and convectors. So what is an EDR?
  • OS&Y valves were often used on high-pressure steam systems and are still used today, but whoever calls these valves out on the drawings?
  • Chain operator. Manager of McDonalds, some other restaurant chain, or a useful HVAC tool?
  • Inlet vanes and the beginning of variable flow air systems. Where do these control vanes get located?
  • Inlet vane turndown ratio. What is that?
  • Vane axial fans — the next generation of variable airflow control. Do you size these fans on static pressure alone?
  • Vane axial fan turndown ratio. How low can you go?
  • Anti-freeze for the hot water heating system freeze protection. Was it really ethylene glycol back then?
  • Water-to-waste air conditioning units. Did the designer really want the water to go down a drain and not be recirculated through a cooling tower?
  • Roll filter. Do you really roll up the dirty portion of the filter?
  • 70% to 80% boilers. Why wouldn’t you specify 90% efficient condensing boilers back then?
  • Air dryer for pneumatic air system. Was this really necessary in an HVAC automatic control application?
  • Conventional HVAC pneumatic control system. What was the standard air pressure?
  • #5 fuel oil. Was there such a fuel grade?
  • #6 fuel oil. Should the oil tank have a steam coil heater in it?
  • Steam driven HVAC pumps. Would these be used with high-pressure, medium-pressure, or low-pressure steam?
  • Pin heater. What is that, and where was it used back in the early 1900s?
  • One-pipe steam system. How does the condensate return get back to the boiler?
  • One-pipe hot water heating system. Does it have a pump and, if so, how does the hot water return to the boiler?
  • Three-pipe heating and cooling system. How’s that work?
  • Standard 1950-1960 hospital HVAC central air system design: 100% outdoor air, 100% exhaust air, and constant volume supply air system. Really?
  • Standard 1950-1960 hospital heating system. Hot water boiler, high-pressure steam boiler, or low-pressure steam boiler?
  • Deaerator versus boiler feed. Is there a difference?
  • Surge tank. Within a steam heating system or hot water system?
  • Steam exhaust head. Where does that go?
  • High temperature pipe insulation in the 1950s and 1960s. What is this white, chalky material?

So these are just some of the terms and technology Trivial Pursuit questions you can use at your next HVAC engineers party. I should note “pin heaters” were used before my time in the business, but all the rest of the terms and technology I have worked with starting back in the 1960s. A lot has changed over all these years. Got anymore HVAC trivia to add to this list?