> Is it possible we were a little premature in abandoning the notion of a
> simple check valve to prevent back flow on parallel connected pumps?  It
> would solve ALL the problems at the cost of reliability of the check valve.

Jim, I agree. I was personally more interested in a series configuration because it appeared to simplify the plumbing, placement, and installation, and because the makers seemed to imply that flow would be unimpeded by the second pump. Thanks to Russell, we know that's not the case, so it's time to reinvestigate the parallel configuration.

I'm still not a huge fan of making my own, although all you folks with the machine tools, power to you! For those not so inclined, you can check McMaster-Carr - they're usually a good source for such things. It's probably where I'll go. They cost money, but they're very heavily tested and quite reliable - I'm more of an electronics nut than a machinist.

Regards,
Chad