As a number of people have commented the bladder in the duct seems problematic. I've worked on duct systems with pneumatically operated dampers before, but never seem something like this. And as I stated in my original post these are only available in 6 states out west, so they are not in use here on the East coast so no exposure to them here for me.
Light is faster than sound. That's why some people seem really bright until you hear them speak.
“If I had my life to live over again, I'd be a plumber.” - Albert Einstein
"Its a table saw.... Do you know where your fingers are?"
I've used these systems a lot, for retrofit applications they work great. Bypass is not necessary except to cure noise complaints - you will raise static pressure in the duct and force more airflow out of whatever zones are calling. With that said, it is NOT meant to be a room by room deal, no matter what the static pressure, to use a previous example: you sure won't get 1200 CFM out of one or two 6 inch runs.
Very useful when someone does not want to buy variable speed blowers and multistage condensers - both of which are better choices, but Arzel works great when set up properly.
No no no I was not trying to be mean......I was saying Yeah for US!!!! Sorry it came across that way!