Pump run time/SWG output

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K

Kjac081

0
Aug 31, 2018
41
League City Tx
Pool Size
20000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Jandy Aquapure 1400
Curious if there is a chart or something out there to calculate pump flow rates at various speeds for a given model pump?

Pool is fairly new and salted in August, so I have limited run experience with this pool, but in August I had things fairly stable with 11 hours run time and 70% SWG output. Now that water temp and air temps are cooler, FC has jumped to 6.5 with a CYA of 40. I dropped output the other day to 50% and FC has not dropped yet.

I know I can start reducing pump run time as part of the equation, but want to make sure I still turn over the water at least once a day (recommended?) before I reduce too much.
Thanks for any pointers.
 
Turnover is a myth.

You first must run your pump enough to create the chlorine. Second thing is to skim the surface to your satisfaction.

I use a spreadsheet to determine run time with % setting to add so much FC to my pool.

SWG Run Time Calculator

Or just do what you are doing. Either reduce your pump run time or your % setting to create amount of chlorine you need. If skimming is no issue, raise your % setting and really reduce your pump run time.
 
Kjac081 said:
Curious if there is a chart or something out there to calculate pump flow rates at various speeds for a given model pump?
Click to expand...


While you can plot a chart of flow rate Vs RPM, the chart will only be valid for a given restriction.

Each pool plumbing configuration is different which presents a different restriction for the pump - Therefore it is not feasible to have a single chart which covers everyone's unique plumbing setup.

Only way you can measure flow rate for your pool is to place an inline flow meter in your plumbing, otherwise it is a bit of a wild guess.


As Marty points out - there is no need to 'turnover' the complete volume of pool water within a specific time frame - It really is a myth...!

While you may think it sounds logical in having to turnover all your pool water every day, there is no science behind this rational.

More important to have good circulation of the water within the pool rather than worrying about how much flows through the pump.
 
Kjac081 said:
in August I had things fairly stable with 11 hours run time and 70% SWG output. Now that water temp and air temps are cooler, FC has jumped to 6.5 with a CYA of 40
Click to expand...

To note are you planning on increasing your CYA?

Per the manual "Chlorine stabilizer should bemaintained between 50 - 75 PPM. With high water temperatures above 30°C, stabilizer (cyanuric acid)must be kept at levels from 75 - 85 PPM"

You would probably need much lower run times if your CYA was higher especially in a warm climate. I'm a bit warmer than you in FL and I try to keep CYA at least at 60 preferably 80. TFP also recommends CYA of 70-80
 
BasicTek said:
To note are you planning on increasing your CYA?

Per the manual "Chlorine stabilizer should bemaintained between 50 - 75 PPM. With high water temperatures above 30°C, stabilizer (cyanuric acid)must be kept at levels from 75 - 85 PPM"

You would probably need much lower run times if your CYA was higher especially in a warm climate. I'm a bit warmer than you in FL and I try to keep CYA at least at 60 preferably 80. TFP also recommends CYA of 70-80
Click to expand...

Yeah, plan on it. Was at 70 but got about 10” of rain in past couple weeks so it got diluted. Regardless, even as low as 40, FC target per pool math app is only 3.
 
To estimate flow, you can check the manufacturer's page for your pump. There should be a brochure and a manual that shows the pump curve.

The pump curve is a graph of the flow vs total head loss.

Total head loss is the pressure of the suction and return in feet of head.

Return head loss is filter pressure x 2.31. Suction would need to be measured with a gauge or you can estimate it at about 40% of the return pressure.

So, multiply filter pressure x 1.4 x 2.31 to get total head loss. Then, see where that hits the graph at the rpm.

For example, if the filter pressure is 18.5 psi at 3,450 rpm and you have a VSFHP270 pump. The total head is 60 feet and and the flow is 100 gpm from the graph.

If you get a vacuum gauge for the suction, that will give you a more accurate number for total head.

Or, you can get a flow meter to check actual flow.

If your total head loss is 10 feet at 1,500 rpm, the flow is 40 gpm.

https://www.jandy.com/~/media/zodiac/global/downloads/sl/sl6201.pdf

Running slow is much more efficient than running fast. At 1725 rpm, the pump uses 1/8th the amount of power as at 3,450 rpm.

Typically, you only need to run fast enough to get skimmer action and make the SWG work.

You could probably run at 1,200 to 1,500 rpm continuously for good results at minimal cost. Just cut back on the SWG percentage.

Power usage follows a cube law. At 1/2 speed (1,725 rpm), the power is (1/2)3 or 1/8th. At 1/3 speed (1,150 rpm), the power usage is (1/3)3 or 1/27th.

You might be about 2,700 watts at 3,450 rpm but only 100 watts at 1,150 rpm. So, it really pays to stay away from the higher speeds.

At 1,150 rpm, the flow is 1/3 but the power is 1/27th.

Try to keep the rpm as low as possible and run longer, you will save a ton of money, it's super quiet and you get nice sparkly water.

If you want to compare "Turnover" (which really doesn't matter), you get the same turnover running the pump at 3,450 rpm for 8 hours as you do running at 1,150 rpm 24 hours. But, the 8 hours at 3,450 rpm costs 9 times as much as running continuously at 1,150 rpm.

That's paying $20 a month vs. $180/month.

Your pump should have the ability to display power usage.

Make sure that that's enabled so that you can see how much power is being used at each speed.
 
How much energy is lost by having SWG run all day? To save pumping energy I have 1400 rpm 24/7 and SWG at 5% output. Pool is super clean and chlorinated. The SWG box is always hot, wasting lots of energy. Wondering if it is better to have SWG on timer only running a few hours/day at higher output. Pump could still run 24/7, no?
 
The SWG should only be using power when generating.

The SWG will use about 150 watts when generating. In standby, the power usage should be minimal.

So, it shouldn't make much difference if it runs 5% of 24 hours or 20% of 6 hours.
 
The heat mostly comes from the transformer. If you have a non-contact infrared thermometer, check your transformer when not generating vs generating.

Maybe use a power meter on the supply to measure power usage when generating vs not generating.
 

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JamesW said:
Maybe use a power meter on the supply to measure power usage when generating vs not generating.
Click to expand...

I was curious about this so I plugged in my SWG (Hayward Aquarite AQR940 Expert Line SWG with 40,000 Gallon Extended Life Turbo Cell) to a Belkin energy monitor to see how much power it was drawing. With the SWG set at 80%, it was pulling an average of 6 watts with the pump running. With electricity at about 0.08/kWH in my market, that only adds up to a few bucks a year. So that can't be right, can it?
 
Was the voltage set correctly for the swg and monitor?

The swg should use about 150 to 180 watts when generating and less than 10 watts when not generating.

The Aquarite shows voltage and amps for the DC side. The volts x amps = watts.

AC volts x AC amps should equal the DC volts x DC amps.
 
Does the Aquarite SWG have a battery? Mine does not lose power when I unplug the unit from the power receptacle. We chose not to hard-wire it so the unit can be unplugged and stored indoors for the winter.

I viewed the energy monitor on and off over the course of an afternoon/evening and the most I saw the unit pulling was 6 watts. At times it was reporting < 0.5W power draw, essentially zero.
 
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