Steve, I'm not familiar with the bumblebee, but it seems that all the pump manufacturers are now coming out with ECM pumps which save tons of energy. It seems the Laing design still wins out to me and are most efficient. They are nearly silent. If you are 5 feet away from them you can't hear them.
I chose the Laing (Bell & Gossett bought the design) not just because of the efficiency but because they have a fluid bearing that will never wear out, there is no way they can leak, and it was easy to sweat a pipe, PEX crimp or 1/2" NPT fitting into them-no flanges, very compact manifold arrangement, and safe for potable water. Their webpage:
ecocirc e3 Whole House Potable Water Circulators – Xylem Applied Water Systems – United States
I posted detailed descriptions of my system, its components, and where I got them earlier in this thread starting here:
http://ecorenovator.org/forum/renova...html#post21961
I might choose the e3-6 pumps for all zones if I did it again, since when all zones are on the total head is enough to really reduce the flow through the zones that have an e3-3 pump. The -6 has enclosed rotor fins for better pumping efficiency where the -3's are open at the top. Or, I could just use smaller loops and not worry about it.
BBP, I like your layout. SSR's are great. My Bell & Gossett controller still uses micro mechanical relays to apply 120v to the pumps, but at 25 max soft start watts with no inductive inrush current, I think they will last longer than me...
My Nordyne AC has a special thermostat, so I used it's micro relay (that would ordinarily turn on a larger relay for resistance heating coils) to complete the call for heat to the hydronic controller, so you can't call for heat and ac at the same time.
For the other zones, I used 24vac duct dampers to close the airflow for the zone to a trickle, plus heat/cool conventional thermostats. If the thermostat calls for heat, the hydronic controller runs the pump and the duct stays closed, so no AC could flow into that zone. If the thermostat calls for AC, the damper opens allowing cool air into that zone, but the heat wouldn't be on at the same time. Since the Nordyne varies its output from 1.5 to 3.5 tons, it runs slowly nearly all day during cooling season-it's already running anytime another zone would need AC. I haven't had any time where AC and heat were called for at the same time, though.