I have read a some post regarding this flow center and wanted to clear some things up. Does the series 7 always run the constant speed pump? The system defaults for the Variable speed are 50% to 100%. I would think that you would want the Variable speed pump to be the only pump on from 0-50% and the constant speed pump should allow the variable speed to modulate from between to get a total of 100%. A 5 ton series 7 requires a min flow rate of 5 GPM for a closed loop and 18 for a max. On heat 2, the VS pump output is 16 % with a flow rate of 13.1 Gpm. Shouldn't the constant speed shut down and the variable speed should be able to cover down to the limit that should be 5 GPM? Any time the unit is on I show Loop Pump K5 on.