Wattage consumption

I have a powerhead that I'm using for a return pump. I guess it's not meant for it but it works and I had it laying around so oh well.

But I guess I'm wondering, am I placing a higher load on the motor than it would normally have. And is it consuming more watts than what it's rated at. It's pushing the water up about four feet.

 

I doubt it, it runs at what it runs at.

however that doesn't mean it runs at what it is advertised as.

 

hmmm...that's a great question - one that I am not sure I can completely answer - but I will throw in my $0.02.

It would depend on the actual rating of the pump. As you have found out, powerheads and return pumps are essentially the same (submerged return pumps at least - for external returns different story).

With that being said, each pump from each manufacturer will have a flow chart. The "nameplate" rating on the pump is @ 0' head or least resistance (only surrounding water). A powerhead will be given this rating as well.

What a submersible return pump will do to go further is to display (usually in manual) the flow rates at different "head heights" (vertical displacement - you said you have 4' which is totally a common height from the sump to the DT).

It's impossible to say without knowing the make/model of the pump if you are truly "overloading" it.

Typically though, the pump will only draw watts for the water it moves and the more resistance the pump gets (aka increasing head height) unless its a VFD (Variable frequency drive - typically only for larger, expensive, industrial/commercial applications) then it's a "direct drive" which means it only spins to the speed the water is moving. That is why for people who have pumps that are oversized for their overflows they install a ball valve that will limit the water that is moved and therefore reduce the wattage consumption of the pump. When it is running full-port open - it will use nearly the maximum wattages it can.

To say that it is "overloaded" - cannot tell unless you posted the make/model of the pump in which case this can be easily put to bed.

hope this helps . . . .(and I hope it's accurate!!!)

 

Cool thanks. It's a "Hagen Powerhead 802", which apparently are now called "Aquaclear 70".

 

By adding head you are actually reducing the wattage since it is pumping less water than it would at 0' head. Centrifugal pumps only draw the power required to do the work at hand plus a little for inefficiencies. You are not overloading it in any way.

 

adding head height usually decreases wattage the diffrence is usually minimal but your not going to damage the pump just the flow is greatly reduced .

that being sead you should invest into a decent pump for a return but do do what i did and im shure others have too i have too much flow for my sump and i have to cut it way back i didnt pay atention the pump rating was at a 4 foot head lol iwaki 30rlxt rocks i should down grade to a 20rlxt and save this one for my 200 gal im working to

but the standard is 3-5 times per hour turnover with the pump i have im close to 11 but i have it cut back to 600 gph from what i measured witch is about 6 times per hour

 

You can cut the wattage significantly by adding head. My OR3500 is rated at 68 watts at 0' head but it is pulling 53 watts measured on a Kill A Watt meter at about 5' head, thats about a 25% decrease which really adds up considering it runs 24/7/365.

 

With all due respect AZDesertRat to me this sounds like a ridiculous statement.

Power is the time integral of work, and work is a force applied over a distance. Work must be done on water to move it, the higher you move it the more work is required. The less time it takes to do an equal amount of work the more power is required.

Saying it takes less power to do more work (move water higher ie more head) sounds ridiculous to me.

Maybe I am missing something...

 

I think if you used your kill a watt to measure the power use with this same pump at 0' head you'd find the pump is just not using the full rated wattage. IME they rarely do. We used to use the same type of meters in my old business (commercial facilities maintenance) and the only time most motors actually drew the rated wattage was when they were failing and dragging internal parts, windings shot, etc. Increasing head would have to use more power unless the head is on the suction side of the pump. (not the case here of coarse)

This would be a fun test set up though. I wish I still had a watt meter to set up a test and see what the wattage difference was (not very much I suspect) between 0 head and 4 feet, 6 feet or other common lifts for aquarium use. The extra wattage to lift 4 feet is probably not much at all and unless it is making the pump run at 100+% of rated wattage it wouldn't reduce pump life enough to notice.

 

I have a watt meter, and I could test this in the next couple days.