Quote:
Originally posted by Cova
I also read most of that thread as it was being made, and though I disagree with a few small points in it, I didn't feel like posting about them at the time. Anyways - which part of my idea did you "used to think that way" about, that you now think differently? The part about bigger pumps adding more heat for increased flow, or the part about friction of the water not making a difference worth worrying about?
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The part about water friction not adding a significant amount of heat.
In short, since mag drive centrigugal pumps are about 70% efficient (i.e. 70% of the power supplied to them is turned into water motion), that energy is countered by the flow restrictions, and induced in the water in the form of heat. So in the case of the Eheim 1048, a 7 Watts heat source is added to the loop.
In the case of an Eheim 1250, rated for 28 (?) Watts, assuming same efficiency (probably lower though), it would add 19.6 Watts of heat to the water.
(of course there's also heat added from part of the remaining 30% of the pump energy, as motor coil heat).