Calculations and need to replace pump, line.

[n2kpk]

Pool size 16x40
28,800 gallons/ 8 / 60=60gpm
1.5 hp Super pump
109 feet of pvc 103 feet of flex pvc 1line to pump
Hayward sand filter 24t
2 skimmers at deep end
2 eyeballs at shallow end
6 90deg elbows
1 tee by skimmers
1 90 by skimmers

The past few years been having problems with water clarity followed the water chemistry wisdom found here which has helped.
But I think pump wise i am under powered either through plumbing or pump.
my calculations are about 98 feet of head all the hardware above.

But with vacuum gauge and pressure gauge this what I get
Pressure 10psi x 2.31 at pump = 23.1
Pressure at port valve 14.5psi x 2.31 = 33.495
Vacuum 22 hg x 1.13 = 24.86
58.335 feet of head with current set up

Can I stay with the current set up or should I replace the suction line? Or is there a pump that can keep up with this setup. And if I replace the line at the skimmers is there a way to connect to 2 inch lines?

Jay

 

[mas985]

IMHO, your current pump is maybe a little over sized, not undersized. I am using a 1/2 HP pump running mostly on low speed. It really doesn't take much to run a pool.

Water clarity and chemistry have little to do with the pump. The pump just helps with distribution of the chlorine and that can be done with any pump. Why do you think it is under powered?

 

[n2kpk]

When I look at some of the pump curves total head vs gpm my head loss seems high. Not sure if I look at these curves correctly.

 

[mas985]

58 ft is typical for that pump and would produce around 60 gpm.

Your calculation was not correct but the measurement probably was.

 

[n2kpk]

Where did I miscalculate? I am trying to learn.

 

[mas985]

I don't now how you calculated head loss but it is far from trivial. But measurements will always be more accurate.

 

[n2kpk]

I don't now how you calculated head loss but it is far from trivial. But measurements will always be more accurate.

I use the charts here to calculate head loss. That is the estimate the was calculated.

 

[mas985]

Sorry but what charts?

 

[n2kpk]

Sorry but what charts?

Hydraulics 101 - Have you lost your head?

 

[mas985]

Again, what charts? I wrote that sticky but never put any charts in it that would allow you to determine head loss of an arbitrary plumbing system because it is just not possible to do with just a chart.

 

[n2kpk]

So would a 3/4 vsp pump be ok?

 

[mas985]

Which pump are you talking about?

 

[Hayward Pool]

Using gauges to determine the TDH on a system only needs two readings. One off the discharge of the pump (pressure gauge) and one off the suction of the pump (vacuum gauge). In looking at your specs I believe you have one reading to many. The pressure gauge at the discharge port will record all back pressure in the system.

 

[mas985]

Pressure 10psi x 2.31 at pump = 23.1
Pressure at port valve 14.5psi x 2.31 = 33.495
Vacuum 22 hg x 1.13 = 24.86
58.335 feet of head with current set up

Good catch. I didn't notice before, but there is clearly something wrong with these measurements. The pressure at the pump should be higher than the pressure at the filter because pressure only decreases away from the pump on the return side. So one of the two gauges is not correct or the first measurement is not actually at the pump drain plug.

 

[n2kpk]

Using gauges to determine the TDH on a system only needs two readings. One off the discharge of the pump (pressure gauge) and one off the suction of the pump (vacuum gauge). In looking at your specs I believe you have one reading to many. The pressure gauge at the discharge port will record all back pressure in the system.

You are correct going back to pump the reading at the multiport valve is 14.5 but the pressure at side of basket is 15 not 10psi. Vacuum the same reading.

 

[n2kpk]

The 58.335 head loss reading was from vacuum at front of basket and pressure from multiport valve.

 

[mas985]

The pump pressure should be used so it is closer to 60' but not that much different.