Quickie plumbing question

Totally false. The power a pump uses is how much water it moves. Move more water, use more power. Simple physics. Throttling a pump does not reduce life one bit. Plugging it in does.

Recircing water in a sump is a waste of power and an addition of unneeded heat. It does not save wear on a pump, it increases it.

 

No you are wrong. And its not acctully simple physics like momentem and position. The pump's energy use is not affected by the amount of water it puts out. When you restrict the flow from the pump you are not changing the speed that the shaft or impeller is spinning, or "working" if you will. The pump does the same amount of "work" if it is wide open or 90% restrited. The amount of "work" is the factor that affects the energy consumtion. Now bigger pumps push more water, causing a need for more power. But changing the flow doesn't affect the power used.

 

OK.... first, on any given hour at my job, I put out 250 million BTUs, generate 257 million watts, consume 20 million watts, and move 4 million pounds of water, and I am good at what I do.

Power is energy in motion. Work is power. In order to do work, you must exert energy over a distance. Voltage is energy, current is distance, power is work.

The work a pump performs is the substance it moves. You really think it takes 1000 watts to spin an impeller of a 8 amp motor? It takes very little to spin a impeller, you loose what ever the power factor is, and the other 80-90% is how much water the impeller moves. Moving more water, takes more watts.

 

what are you doing? do work at a damn?

true I am not disagreeing with you there

These aquarium pumps are engineered different then what ever it is you are using to move 4 mil lbs of water. Lets just say they draw 2amps, that will give you the max flow of the pump. No you throttle back that pump the little cord plugged into the wall is still drawing 2amps. It may not all be doing "work" but the 2amps are still being taken for you outlet. Thus it will not lower you power intake. I talked to the manufacture...the power intake is the same. But know I am going to go and check it to find out. My buddy has a tool to see what a electrical device draws.

All I wanted to know what if I would loose flow jumping up to 1" flex tube from 3/4" PVC, and if I should exchange the 3/4" for 1"

 

Coal fired power plant.

All motors are either induction motors or syncronous motors. Our induction motors are no different than any other induction motor, they just have terrible power factor.

Your understanding of electricity is not correct. Water slows a impeller, yet the frequency of the power needs to stay the same. The slip angle increases and draws more power to keep running the same speed. Moving more water takes more power.

By your logic a dimmable 100w light still draws the same 100w even dimmed down. It does not. Watts = voltage times current. Voltage stays the same current increases. We are not paying for the spinning of an impeller, we are paying for moving water.

 

Do these pumps have a flow control on them? If so, the difference is like a dimmer switch and regular on/off switch.

BTW I am not trying to be a jerk-off, just trying to get this right

 

Ok so I guess I did explain my self right. because you are right the dimmer does change the amount of power to the light. But the drive on the pump is set to spin at a certain speed, its max, that speed wont change if you throttle down the out take of the pump. Just because its not moving the same amount of water doesn't mean the drive is slowing taking last power.
I understand what you are saying, It makes sense, I just believe in this application there is a difference. But this weekend I will find out. I am going to preform some experiments and find out.
And yes you are right it does take more power to move more water
And you are paying for the spinning of the impeller, thats what moves the water.

 

This is a very interesting thread. make sure to post when you hear from the manufacturer.

 

There is no drive on a pump. It spins based on 60 hz. The amount of current draw is based on the degree of slip angle between the stator and the rotor. The more water moved, the more drag on the impeller drag, the higher the angle, the higher the current drawn, the more power used.

Power has nothing to do with frequency or speed of the impeller, it is only voltage across two points and current flowing between them. I'm not talking about special variable frequency drives or hydraulic couplings. Only plain old simple induction motors. About 80% of all motors in use are induction motors including aquarium pumps.

Water weighs 8 pounds a gallon...mass. Moving mass requires energy. Once a body is in motion, it will stay in motion (unless acted upon). Moving mass over a distance is work. If you close a valve on a pump, the only power consumed is the power needed to overcome the mechanical resistance. Mechanical friction. Very little. Then there is the loss to the fluid the impeller is spinning in. Fluid friction. Very little. Then there is the loss to heat which is expressed with power factor. That does not equal max current drawn on the label. Moving a mass of water is not free. Opening the valve and moving mass takes power.

Max power is max head pressure... which is stated in max cut off height. If you take a Mag motor and it says the max cut off is 20 feet, and you put a pipe up 20 feet, the pump would lift a column of water twenty feet and it would no longer move water. No water would be moving, but it would be using max power because it would be holding up a column of 20 feet of water against gravity. If you put a valve at the outlet of the pump and closed it, it is not doing any work, it is not holding any weight, it is not moving any mass, just spinning.

 

I'm loving this thread!! Very informative!