[bigben2k]

Thanks Dave.

To get back to my practical approach, could we take a minute here and run some calculations on that Eheim 1250, at 100 gph?

Like I wrote earlier, at 100 gph, the pressure drop will be 2.4 psi. The pump uses a 28 Watt source. Where do I go from here?


DixDogfight: you wrote: "Do you dissagree that it takes 6.5W of power to move 1200l/h to a height of 2m with a 100% effective pump?". I don't quite see the relation with the Eheim 1250, since it can't achieve that. It's either 1200L/h at 0 head, or 0 L/h at 2meters. What's up?


To recap what we have so far (correct me as necessary!):

-A pump uses a fix amount of energy, supplied in electrical form. (*** correction: a variable amount of energy***)

1-In a centrifugal design, less than 50% of that power is converted to create a flow (outlet to intake). This energy is converted to heat, from friction of water-on-water within the loop.

2-The remaining energy appears in the form of: churning, and energy loss. The churning again, induces heat from the water-on-water friction.

2b-The energy loss includes:
-Motor inneficiency (i.e. not all of the EM field generated by the coils moves the impeller)
-Heat from the coils (i.e. the coil wires, not being superconductors, dissipate some power)
-Friction/noise (as the impeller rattles around the housing)
-Noise (as the coils rattle, if applicable)