Originally Posted by Ashcroft
Wow this is like a flashback to the bad old days, when we only had voltage control for pumps.
So, as has been said it isn't really possible to combine two D5 strong on the koolance controller. Well, you could, but it wouldn't last long and maybe catch fire.
The rpm wire on the D5 strong is just a feedback for speed with no control function. The pump speed is determined by voltage alone (well, by flow rate too but that is beside the point) so to control both pumps speed you will need two variable voltage supplies or one with enough wattage for both.
Twin D5 strong is an excessive amount of power so are you sure it is really needed?
As toolmaker said if the pumps are going into a single loop you could have a fair degree of flow control by running one pump at a fixed speed and controlling one. There is no problem with running them at differing speeds.
Otherwise a second controller is really a necessity. Boy I don't miss these problems at all. The rp452 is a great device, it was really useful to be able to use it for single loop, dual loop or just as a single pump. I always hated those pumps though.
Ah I get it now, it was a bit late the other night, and my brain wasn't working up to scratch...yeah this gear is old, I bought a whole heap of stuff off of a guy (Silverstone TJ11, the res, controller, fittings, radiators, other bits and bobs) for $300aud, the stuff would of retailed all up for about $2500 back in the day, so I couldn't pass it up, so I'm just trying to put it all to use.
I guess I will just run one D5 strong on the controller, and either supplement its flow with a normal D5 running straight off of the PSU, or just get two D5 Strong's and have a 12v to 24v converter to power the uncontrolled pump at full 24V at all times.
Thanks for the advice guys, much appreciated.