How long should I run my pump?

[randelli]

I am trying to determine how long I need to run my pump to get 1 turn-over per day.

I have a WhisperFlow WFDS-6 dual speed 1 1/2 hp pump and 19,000 gallon pool. There is a chart on the last page of this document www.poolsuppliestoday.com/pdf/pent_whisperflo.pdf but I don't understand how to read it. If I follow the curve for the WFDS-6 it looks like it pumps a little over 80 gpm at 3450 RPM and about 130 GPM at 1750 RPM. This does not make sense to me as I can visually see more water being moved at the higher rate. Like I said - I don't know how to read this chart so I am misinterpreting the data.

I need to run the pump on high speed for a while to operate the hayward sweep (POS) and then I want to run on low speed until I get the turn-over. Any suggestions? BTW, I have it set for 1.5 hours on high and 2.5 on low, at the moment.

 

[JasonLion]

Low speed will move exactly half as much water as high speed. That doesn't solve the entire question, but it does allow you to adjust the mix of high and low speed while maintaing the same total water movement.

I prefer to determine the ideal pump run time empirically, instead of trying to calculate the flow rate (which is prone to guessing and approximations). See this article in pool school.

 

[mas985]

Best case, the pump is probably putting out 100 GPM on full speed 50 GPM on low. Worst case, probably 80 GPM on high speed, 40 GPM on low. So even for the worst case, the turnover is 4 hours on high speed and 8 hours on low speed. To start, you could set it up for a half turnover on high (2 hours) and then a half turnover on low (4 hours). This will give you one turnover per day which is about least amount of run time you would want except for winter time. During the heat of the summer, you will probably want to have at least two turnovers and you can split that up any way you want (e.g. 2 hours high speed, 12 hours low speed).

 

[randelli]

OK, but with the extremely high power costs here in CA, I would like to find a shortcut to what is described in the article. It seems that there would be better reporting than the characteristic curve included in the owners manual. I imagine that the curve would be different depending on the size/length of pipe to and from the pool; and number of 90's in the way.

I wonder if I could measure how long it takes to fill a 5 gallon bucket and then extrapolate the result?

 

[mas985]

Note that if you attempt to redirect water into a 5 gallon bucket that changes your head loss which affects the flow rate so that is unlikely to give you a more accurate estimation. However, if you want a better approximation to your flow rate, you need a good estimate to head loss. There are a couple of ways to do that but the easiest is to use your filter pressure and knowledge of your pool plumbing. I describe the process in the Hydraulics 101 link in my signature.

If you want something even more accurate I can help but I need to somethings about your plumbing setup:

Filter pressure
Pump model/size
Length, diameter and number of suction lines pool to equipment pad
Length, diameter and number of return lines pool to equipment pad
Number of return eyeballs

But as Jason pointed out, knowledge of the exact turnover rate tells you little about what the pool actually requires. That can only be determined by trial and error.

 

[randelli]

Note that if you attempt to redirect water into a 5 gallon bucket that changes your head loss which affects the flow rate so that is unlikely to give you a more accurate estimation. However, if you want a better approximation to your flow rate, you need a good estimate to head loss. There are a couple of ways to do that but the easiest is to use your filter pressure and knowledge of your pool plumbing. I describe the process in the Hydraulics 101 link in my signature.

If you want something even more accurate I can help but I need to somethings about your plumbing setup:

Filter pressure
Pump model/size
Length, diameter and number of suction lines pool to equipment pad
Length, diameter and number of return lines pool to equipment pad
Number of return eyeballs

But as Jason pointed out, knowledge of the exact turnover rate tells you little about what the pool actually requires. That can only be determined by trial and error.

You know, if you don't mind, I'll provide the information to you for a little input. I read your thread; but it is a little over my head at the moment.

Here is the basic extent of my pool knowledge at the moment:

1) the BBB method works pretty darn good
2) bleach can ruin clothes in a hurry
3) it would have been better to wear 1 pool maintenance outfit everytime than create the 8 outfits I have now

 

[randelli]

If you want something even more accurate I can help but I need to somethings about your plumbing setup:

Filter pressure
Pump model/size
Length, diameter and number of suction lines pool to equipment pad
Length, diameter and number of return lines pool to equipment pad
Number of return eyeballs

Filter pressure - 8 PSI on high/ 3 PSI on low speed

Pump model/size - WhisperFlo WSDS-6 1.5 hp dual speed 3450/1725 going into a Tagelus 100D Sand Filter

Length, diameter and number of suction lines pool to equipment pad - (2) lines about 20'. (1) 1 1/2" and (1) 2". I don't know which goes to the skimmer and which goes to the the main drain. I assume the 2" is going to the main drain as the suction attachment to the sweeper is not on the skimmer side of the 3-way valve.

Length, diameter and number of return lines pool to equipment pad - (1) 2" line. About 30' to the first eyeball and 25' to the second eyeball. Total of 55'

Number of return eyeballs - 2

Here is a picture of the equipment. You can see the 1 1/2" pipe on the left side of the 3-way valve. To get maximum suction for the sweep I turn the valve all the way to the left:

 

[mas985]

With your setup, I get something closer to 14 PSI for the filter pressure which could mean one of two things. The filter gauge is bad or there is a lot more suction loss than I would normally expect.

Does the gauge go to zero when the pump is off?

Was the filter pressure with both the simmer and main drain on as shown in the photo?

Does the pump sound loud when on high speed?

Is there any air in the pump basket?

What diameter are the eyeballs?

If it is a bad gauge, then the flow rate should be about 104 GPM with a turnover rate of 3 hours. On low speed, 53 GPM and 6 hour turnover. If the gauge is correct, then the flow rate would be 82 GPM on high speed. So it is still within the range I gave earlier.

 

[randelli]

With your setup, I get something closer to 14 PSI for the filter pressure which could mean one of two things. The filter gauge is bad or there is a lot more suction loss than I would normally expect.

Does the gauge go to zero when the pump is off?

Was the filter pressure with both the simmer and main drain on as shown in the photo?

Does the pump sound loud when on high speed?

Is there any air in the pump basket?

What diameter are the eyeballs?

If it is a bad gauge, then the flow rate should be about 104 GPM with a turnover rate of 3 hours. On low speed, 53 GPM and 6 hour turnover. If the gauge is correct, then the flow rate would be 82 GPM on high speed. So it is still within the range I gave earlier.

Does the gauge go to zero when the pump is off? - yes

Was the filter pressure with both the simmer and main drain on as shown in the photo? - yes

Does the pump sound loud when on high speed? - YES, and it is loud on low speed, definitely NOT "whisper"

Is there any air in the pump basket? - a small amount at the top of the lid

What diameter are the eyeballs? - They are smaller than the sweep and larger than my index finger, 1 1/4"??

NOTE: There is a small amount of water that drips from the fitting at the top of the pump. I may be losing suction there?

 

[mas985]

Does the pump sound loud when on high speed? - YES, and it is loud on low speed, definitely NOT "whisper"

This concerns me a little bit and could indicate a suction side problem but I'm not entirely sure yet.

Have you ever tried to back flush the skimmer and main drain lines to make sure they are clean of debris?

If you move the suction valve to skimmer only or main drain only, does the noise get louder?

What is the filter pressure when you do that for each setting?



Sorry for all the questions but I just want to make sure there isn't an issue anywhere.

 

[randelli]

I'll check these out tonight when I get home - if the storm permits.

I had a blockage last year at the 3-way valve on the sweep side. I will open that valve and see if there is anything there.

 

[mas985]

So I may be a bit confused. Is the main drain plumbed through the skimmer and there is only one line comming back to the valve and the other side of the valve is only the cleaner?

 

[randelli]

That IS a good question.

We are the 4th owner of the house/pool that was built in 1987 so I do not know how the pool was plumbed.

I do know that one side of the valve works the skimmer and the other side works the sweeper. The skimmer has (2) holes - one to the pump and the other one might go to the main drain? I always assumed the main drain was tied to the sweeper but i am probably wrong here. That is happening more and more these days.

Your description above could very well be the configuration. How would I verify that? Is this a normal installation?

 

[mas985]

Look at the bottom of the skimmer and see if there are two holes. If so and neither is plugged, then one goes to the pump and other to the main drain. This is fairly common so it wouldn't surprise me. But that also means that you have only one 2" suction line for both although that really shouldn't be a huge issue unless it has a clog as well. If the pump gets real loud or you see lots of air in the pump basket when just the skimmer line is on, then there could be a problem.

 

[randelli]

ARRRRRGH!!

The storm has past and I have a day off from work. I went out to get marks results and discover that the pump shuts off on high speed. It is overheating. Now I am tearing the pump apart to find the problem.

I have all of the bolts out, and the pump section is loose, but will not come all the way off. I will have to read the manual I guess

 

[mas985]

Sorry to hear that. How old is the pump? The loud pump noise that you heard could be symptom of the problem as well.

 

[randelli]

OK I removed the diffuser and the shaft cap and the impeller set screw. My pool vernacular is growing today.

Any tips on removing the impeller? I have a 1/2" wrench on the shaft and I am attempting to turn the impeller counter-clockwise. So far I have only been successful at removing skin between the 1/2" wrench and the wedding band.

Am I missing something??

 

[randelli]

Sorry to hear that. How old is the pump? The loud pump noise that you heard could be symptom of the problem as well.

The pump and filter are about 3 years old??

I think the impeller is just snugged to the shaft and I need to find more leverage and less hinge points. I am hoping to find something lodged that I can easily remove and put it all back together again.

 

[mas985]

You shouldn't need to remove the impeller to clear it. Just rotate by hand it and look into the vanes for debris. A pipe cleaner can be used to make sure it is all clear.

 

[randelli]

I found this great rubber strap wrench that got the impeller off. I did not see anything wrong inside the pump so I cleaned everything real well and lubed the moving parts and put it all back together again. I also took the pipes apart and put some more teflon tape on the threads to stop air leaks.

The motor is still overheating and turning off on high speed. Of course, the pump won't prime on low speed, so I need to find out what is causing the motor to heat up. The shaft was very easy to turn without any of the pump parts attached.