what determines heat from return pumps?

[homeboyreefer]

Does power draw (watts) determine heat or the brand of pump

So take for example a mag 7 that need 70 watts @ 750 gph

versus

quiet one 6000 that needs 140 watts @ 1500 gph

would the mag 7 put out half the heat then the q/o because of the wattage or would the quiet one put out the same heat or less because its a better brand/pump and still double the gph.


And how loud are these two pumps?

 

[GSMguy]

The quiet one is a better brand? Because why?

It has to do with the pumps design really, the heat given off by say a mag does seem to be higher per watt used than an eheim.

I use a Quiet one for mixing saltwater and alone it heats a 5 gallon bucket of water to 80 degrees in a couple hours, my eheim 1250 would take all day.

 

[Hal]

You're mostly right.

Watts = work done pumping water + waste heat.

If you have two pumps that have the same wattage but one pumps more water, the one that pumps more water will create less heat. Conversely, if you have two pumps that pump the same amount of water, but one uses less wattage, the lower wattage pump will create less heat.

Just make sure that you have the actual pump rating for the gph that you're looking at. So, for example, although you say that the Mag 7 is 70 watts to create 750gph, you may not be able to extrapolate that to using 140 watts to create 1500 gph. This is because the pump performance most likely is NOT linear. I could be wrong about this, so check with the pump manufacturer if you're going to use this extrapolation technique.

If on the other hand, you can compare two pumps with manufacturer specs that are identical for either wattage or gph, i.e. pump 1: X1 watts at Y1 gph, matched with either X2 watts at Y1 gph or X1 watts at Y2 gph, then you can do a straight comparison using my formula above (watts = gph work + heat) .

 

[Aquarist007]

<a href=showthread.php?s=&postid=14925632#post14925632 target=_blank>Originally posted</a> by Hal
You're mostly right.

Watts = work done pumping water + waste heat.

If you have two pumps that have the same wattage but one pumps more water, the one that pumps more water will create less heat. Conversely, if you have two pumps that pump the same amount of water, but one uses less wattage, the lower wattage pump will create less heat.

Just make sure that you have the actual pump rating for the gph that you're looking at. So, for example, although you say that the Mag 7 is 70 watts to create 750gph, you may not be able to extrapolate that to using 140 watts to create 1500 gph. This is because the pump performance most likely is NOT linear. I could be wrong about this, so check with the pump manufacturer if you're going to use this extrapolation technique.

If on the other hand, you can compare two pumps with manufacturer specs that are identical for either wattage or gph, i.e. pump 1: X1 watts at Y1 gph, matched with either X2 watts at Y1 gph or X1 watts at Y2 gph, then you can do a straight comparison using my formula above (watts = gph work + heat) .

great physics lesson---thanks

what happens in the case of using a ball valve to restrict the flow on a pump. Will the restriction in flow be converted to heat?