DC Pump - Restricting Outflow Vs Controller Voltage

[jduong916]

When you restrict the output on a DC pump does it use less wattage than what the controller shows?

 

[Red_Beard]

probably, yes. Anytime you restrict output, you increase the load on the motor which in turn will increase wattage. The only question is how they built the controller. If wattage use reported is coming from a hall effect sensor or something, then it will be true to use. But, if it is coming from a 'preset' positional based wattage, then restricting the output will make it use more than it is reporting.

 

[Stakenshake]

probably, yes. Anytime you restrict output, you increase the load on the motor which in turn will increase wattage. The only question is how they built the controller. If wattage use reported is coming from a hall effect sensor or something, then it will be true to use. But, if it is coming from a 'preset' positional based wattage, then restricting the output will make it use more than it is reporting.

This is only true for axial flow pumps (think mp40). Axial flow pumps the power is inversely proportional to flow. As flow goes down power goes up. This is due to axis flow pumps act more like a positive displacement pump with each rotation.

For centrifugal pumps (typical return pumps) the flow is directly proportional to power. This is due to centrifugal pumps create head pressure which then results in fluids to flow.

 

[jduong916]

This is only true for axial flow pumps (think mp40). Axial flow pumps the power is inversely proportional to flow. As flow goes down power goes up. This is due to axis flow pumps act more like a positive displacement pump with each rotation.

For centrifugal pumps (typical return pumps) the flow is directly proportional to power. This is due to centrifugal pumps create head pressure which then results in fluids to flow.

So, for a DC pump, if you restrict the flow after the output and the controller is set at max wattage, the wattage used will be lower just like it would be on an AC pump? The wattage that the controller states would be higher than the actual wattage used?

 

[jduong916]

probably, yes. Anytime you restrict output, you increase the load on the motor which in turn will increase wattage. The only question is how they built the controller. If wattage use reported is coming from a hall effect sensor or something, then it will be true to use. But, if it is coming from a 'preset' positional based wattage, then restricting the output will make it use more than it is reporting.

If you decrease the flow you decrease wattage use on a return pump.

 

[Red_Beard]

So, for a DC pump, if you restrict the flow with a controller set at max wattage the wattage will be lower just like it would be on an AC pump? The controller stated wattage would be higher?

No. he is saying that if you decrease the flow in a centrifugal style pump it will decrease wattage, regardless if it is AC or DC powered.

 

[jduong916]

No. he is saying that if you decrease the flow in a centrifugal style pump it will decrease wattage, regardless if it is AC or DC powered.

That's what I just said. Restrict the flow = decrease the flow.

 

[Red_Beard]

That's what I just said. Restrict the flow = decrease the flow.

yes. irrespective of alternating or direct current. again, it depends on how they built their controller. If it has a hall effect sensor, you will have an accurate reading of wattage. if it is just based on where the dial is, it may not be accurate. If you have a killawatt or other means of measuring current draw, you would be able to verify that.

 

[Stakenshake]

So, for a DC pump, if you restrict the flow after the output and the controller is set at max wattage, the wattage used will be lower just like it would be on an AC pump? The wattage that the controller states would be higher than the actual wattage used?

Like what red beard said it depends on how the controller is made if it’s a real reading or not. Use of a killawatt meter would confirm. But assuming your pump is centrifugal and you restrict the flow it will go down in wattage.