- May 3, 2007
- 18,185
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
Backwash procedure for pool with 2 filters
- Thread starter JPMorgan
- Start date
I suspect that the RPM is probably ok, but I would still like to see it actually tested if it can be done easily enough.
Would the item below get the job done? Do I just hold the tachometer next to the spinning motor shaft? Does there need to be any kind of mark on the shaft, i.e., a dot of nail polish? I'm looking for 3500 RPM, correct? If that checks out, does that rule out any issues with power/wiring?
Another option... looks similar
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Looks Ok.
Yes.
Looks like it comes with reflective tape.
You could probably use a spot of white paint or white nail polish.
Yes.
It would be a good sign that the power is probably ok.
However, measuring the power can indicate the flow based on the graph MAS985 provided earlier.
For example, if the power is 5,000 watts, then the flow is estimated at 120 gpm.
If the power is about 5,850 watts, then that puts the flow closer to about 170 gpm.
If the power is about 5,850 watts, then that puts the flow closer to about 170 gpm.
If the pump is not on the pump curve, then the power will be lower than expected.
So, a power check will be very helpful.
So, a power check will be very helpful.
- May 3, 2007
- 18,185
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
One thing to be aware when determining GPM from watts is that the slope of that line is fairly shallow so a small error in watts tends to create a large error in GPM. Added to that is the lack of exact measurements for that particular pump so I am uncertain how accurate this method will be.
In the past, I have found that for some pumps where the data is fairly accurate, you get reasonable results but even when there is measured data (Energy Star), that data isn't always precise and can result in some fairly high errors.
I did notice from the label that the motor rating is 4860 watts (V*I*PF*sqr(3); PF=1) and NEMA tolerances are += 10% so the motor should not draw more than 5346 watts. Based upon the head curve and power curve, the best efficiency point of the pump motor combo is around 125 GPM at 114' of head and 5070 watts. To the right of that point, the power vs GPM tends to have a non-linear relationship and can actually start to reduce again. But again, without exact data, it is hard to know for sure what will happen.
In the past, I have found that for some pumps where the data is fairly accurate, you get reasonable results but even when there is measured data (Energy Star), that data isn't always precise and can result in some fairly high errors.
I did notice from the label that the motor rating is 4860 watts (V*I*PF*sqr(3); PF=1) and NEMA tolerances are += 10% so the motor should not draw more than 5346 watts. Based upon the head curve and power curve, the best efficiency point of the pump motor combo is around 125 GPM at 114' of head and 5070 watts. To the right of that point, the power vs GPM tends to have a non-linear relationship and can actually start to reduce again. But again, without exact data, it is hard to know for sure what will happen.
If it is not running on the pump performance curve, like with the wrong impeller, then it should be more obvious due to extra low power draw?
- May 3, 2007
- 18,185
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
Yes, even though the power curve may not be exact, we might still be able to determine significant deltas that might indicate a particular issue.
Also, I made a slight adjustment based upon the label wattage to make the pump motor a little more efficient and I put the possible plumbing curves as an overlay.
Operating point A' assumes:
- Pump pressure and suction gauge measurements are correct
- Flow meter measurement is incorrect
- Pump is operating on the DMJ head curve
Operating point B' assumes:
- Pump pressure and suction gauge measurements are correct
- Flow meter measurement is correct
- Pump is NOT operating on the DMJ head curve
Operating point C' assumes:
- Pump pressure and suction gauge measurements are incorrect
- Flow meter measurements are correct
- Pump is operating on the DMJ head curve
Is the orange line the DMH Power Curve?
It says WhisperFlo.
Why two different colors for the DMJ Power Curve?
It says WhisperFlo.
Why two different colors for the DMJ Power Curve?
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- May 3, 2007
- 18,185
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
At this point, we need some more data including:
1) Pump RPM.
2) Pump Power Draw with associated Vacuum and Discharge Pressures and Flow rate in GPM.
3) New Vacuum and Discharge Pressure Gauges with new readings.
4) Maybe a new Flow Meter added to see if it is in agreement.
5) Verify all pump parts are correct, in good condition and no parts are missing.
1) Pump RPM.
2) Pump Power Draw with associated Vacuum and Discharge Pressures and Flow rate in GPM.
3) New Vacuum and Discharge Pressure Gauges with new readings.
4) Maybe a new Flow Meter added to see if it is in agreement.
5) Verify all pump parts are correct, in good condition and no parts are missing.
Can you show the power meter that goes to the pump?
What else is on the three-phase power supply?
What else is on the three-phase power supply?
All of this is getting way over my head. I am just going to print out your graphs and questions and show them to the PC to get answers.
By power meter, do you mean the electric meter (just like I would have at a residence)? What will that tell us?
I don't understand. What else might be on the three phase power supply and how would I know. Again.... I think I need to turn to the PC(or an electrician) to answer some of these questions. I will try to get answers to all the questions in Post #194 above.
Yes.
If we can see how much power the pump is using, then that will give us an idea about flow and head loss.
I would think that the property has a single phase supply and a three-phase supply with separate meters.
Find the three-phase meter and see how much power is being used with the pump on and then with the pump off.
If the pump is the only thing on the three phase meter, then that will be easy.
If there are other things, you can still tell the difference as long as the other things are steady and not changing.
Maybe you can turn off the other things on the three phase supply so that the pump is the only thing on.
Alternatively, you can measure power directly on the pump, but most people will not be able to do that correctly.
In the image above is "Plumbing Curve OP A" supposed to be a solid line? There is no solid line in the image (as indicated in the legend) and the legend does not have a line with dots and dashes which is in the image.
- May 3, 2007
- 18,185
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
That is just a quirk of Excel. It is the line with two dots.
Flow meter is currently measuring about 130 gpm. If I underestand the graph correctly, that would mean that the pump suction and pressure gauges would have to be way off.... closer to 140 ft of head... if the pump is operating on "Plumbing Curve OP C". Is that right? Seems like "Plumbing Curve OP B" would be the most likely condition (as previously surmised).