[vreihen16]

Back in the early 1990's, my employer had a high-pressure small-duct AC system installed in two office suites across the hall from my office at the time. It was supposedly the bleeding edge of AC technology at the time, using several ducts the size of vacuum cleaner hoses into each room. When it was new, the airflow was so strong that it used to blow papers off of people's desks!

Over time, the airflow dropped off noticeably. I was moved into one of those offices when the system was about 17 years old, and had to buy my own portable AC unit because the high pressure system couldn't even blow a draft in my new-to-me office any more. The HVAC repair guy (not trained on this system) said that the squirrel cage fan blades flattened themselves over time, which is why it could not move air. More likely, the ductboard and tape distribution plenum that the original installers fabricated blew apart over time from the high pressures, and was leaking in the ceiling.

Anyway, I'm mentioning this because these systems are still available from at least one manufacturer, and are being targeted as retrofits for historic/landmark buildings where the hoses can be routed inside existing interior walls. Definitely not something that I would use in a new construction, though.....