Sentry Air System

I am an engineer. I have friends who were in need of my help because they purchased the Sentry system. The unit was failing to remove odors and was causing a serious problem with neighboring businesses. They came to me to resolve the problem.
I disassembled the unit down to the last bolt. My findings completely corroborated the findings in my initial review of the unit.
The unit is designed backwards. The media that removes particulates and organic vapors and fumes is downstream (after) of the impeller that provides suction. That means this: A Sentry system that is perfectly maintained will accumulate tar, buildup and condensate on the rotating machinery and the interior walls. There is no rebuttal to that fact. To use an analogy, think about the home heating furnace where you live. If the Sentry system was your home furnace, the air filter would be placed at your room air registers. That will certainly fuilter the air going into the room, but your expensive furnace impeller and ducting is exposed to every parcel of dust and particulate unfiltered. That is exactly how the Sentry system is design. The filter is downstream of the expensive rotating machinery.
It took me two days to clean the accumulated buildup inside the Sentry system.
So, I redesigned it. I produced mechanical drawings of a module that bolts onto the Sentry system. The module filters the air drawn in BEFORE it touches the surfaces of the impeller. I designed a tray that slides in with a web basket that allows the owner to replace the activated charcoal using far less expensive bulk media. Reputable sources of coconut shell charcoal sell a year’s worth of media for less than the cost of one Sentry filter replacement. The redesigned system uses HEPA filters that can be purchased at any big box home improvement store. We tested the redesigned system and it works better than the Sentry design. I’ve been asked to have another module made. Read: I have no intention of building kits to fix the Sentry design. I only illustrate a point. The Sentry system could be designed far better. I did design it better! The Sentry system is designed backwards and the replacement filters are incredibly overpriced. Ever hear the one about giving away the razor blade to get the recurring chance to sell the blades?
The other design issue I found was even scarier. Sentry’s system includes a large impeller that rotates at high RPM less than 1 inch away from the 115V input power cable. I was shocked to see that the only thing that prevents that high voltage cord from contacting the impeller was a zip tie. No clamp or shield — just a large metal impeller rotating at over 1000RPM with the power cord less than an inch away secured by a zip tie.
I stand behind this review. This is a very expensive filter and I did not appreciate how poorly customer service treated us. Interestingly enough, they did us a favor.