bypass verses flow through
The Canavac web site has some interesting information on this topic. It does seem that flow through motors may provide more power but the bypass motors will last longer. Supposedly the Domel flow through motors in the Drainvac units are designed to last 25 to 30 years, I'm not sure if that will actually happen. I do have some central vacuum units in my collection that use bypass motors, you can usually tell a bypass motor from a flow through by the sound. The canavac web site article has the view that many manufacturers are using the flow through motors because they are cheaper and provide just as much power, if not more.
Mike
[URL unfurl="true"]http://canavac.com/central-vacuum-motors/[/URL]
