Backwash procedure for pool with 2 filters

[JamesW]

With the VS Pump, you could adjust the speed up to the exact required level and not higher.

This will meet the needs without going higher than necessary.

 

[JPMorgan]

Variable speed would allow you to turn it down at times where the full speed is not required.

I believe the state requires 170 gpm constantly. If that is the case does a VS pump make sense?

 

[Lake Placid]

VS would allow you to run at the lowest speed possible to maintain 170 gpm, thus some potential for energy savings. Given the referenced pump has flow control, you could try and use that to maintain the requisite GPM flow as the filters clog etc, it theoretically would increase speed to allow you to stay within regs. Is that really necessary, no. I’ve never seen a health inspector standing over a flow meter waiting to shut you down when the flow rate drops to 169 gpm. Typically they just check the box that you have a flow meter installed and move on with their day, probably not even looking at the flow rate.

 

[mas985]

If the flow meter is correct and the pressure/suction measurements are correct, the current operating point would be
120 GPM @ 81.5 ft of head and a plumbing curve of:

Head (ft) = 0.00566 * GPM ^2

Which crosses the Whisperflo 5 HP head curve close to the same operating point of 120 GPM @ 81.5' of head. So this pump may not be any better.

Of course we are still not certain which measurements are correct and if the current pump is operating as indicated by the head curve.

 

[JamesW]

 

[mas985]

DMH impeller is actually closer to the measurements.

 

[mas985]

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

Only one of these is valid

 

[JamesW]

Only one of these is correct

Maybe put a new vacuum gauge on the suction and a new pressure gauge directly after the pump.

 

[JamesW]

Are we 100% sure that the pump is rotating the correct direction?

For 3 phase power, it is easy to get reverse rotation.

Can you show a video of the operation with the rotation being verified?

Can you check the RPM?

Can you check the power being used?

What is the voltage being used?

Check amperage on all three wires.

 

[JamesW]

Only one of these is valid

It could be a combination of all three things being off.

- Pump pressure and suction gauge measurements are incorrect
- Flow meter measurement is incorrect
- Pump is NOT operating on the DMJ head curve.

In my opinion, the Pump NOT operating on the DMJ head curve is the most likely issue.

 

[mas985]

In my opinion, the Pump NOT operating on the DMJ head curve is the most likely issue.

That was my thought as well.