Forgot yours was a drainback system-easier to just use 2 pumps and 1 each of the e5's and e10's should work great. Ball valves are the easiest way to throttle flowrate. If you are using separate pumps anyway, unless you can take advantage of stratification (difficult in a shallow tank), you may as well just let them run full bore and get better efficiency out of the collectors.
Another thought-some of these Laing designs are also available in variable speed like the potable e1/e3's like I have. This would allow you to finetune flowrates by dropping power consumption, saving energy. You may want to kick around and see if they offer other variants suiting your needs that come with a speed control.
The only downside (a small one compared against the benefits) to these pumps is since they are electronically commutated, they probably won't work on a PWM variable speed control. My SR728C can control 2 arrays simultaneously and one of the pump outputs can be set normally or vary pump pulsewidth to maintain a specific deltaT across the collector array as solar energy waxes and wanes.
__________________
"I‘d put my money on the sun and solar energy. What a source of power! I hope we don‘t have to
wait until oil and coal run out before we tackle that." Thomas Edison, 1847 — 1931
|