Why is calculating run-time for my new VS motor so difficult?

ron_jeremy

Member
May 5, 2016
24
CA
Just replaced a 1-speed motor with a vs motor but kept the same pump. After a lengthy chat session I was able to get absolutely nowhere with INYOpools regarding how long I should run the motor to filter the pool.

Pool is approx. 25,000 US gallons.
Here is the oringal motor + pump:
pentair-sf-n1-2a-340040-01.jpg
pentair-sf-n1-2a-340040-02.jpg
New motor is a V-Green variable speed 2.7HP as seen here: A.O. Smith V-Green 2.7 HP Square Flange 48Y Variable Speed Motor - ECM27SQU - INYOPools.com

I was hoping to find a chart or at least a basic 'cheat sheet' that would list the approx. flow rates at say 100 rpm intervals or something so I can make some basic calculations to setup the motor and get on with my life. Instead, after chatting with INYOpools, I feel like I've just gone down some rabbit hole and am asking unanswerable questions.
 

Texas Splash

Mod Squad
TFP Expert
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Jun 22, 2014
33,887
Texas, San Antonio/Marion, South-Central Area
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17888
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CircuPool RJ-45 Plus
The days when people tried to get numbers-specific about pump run time, primarily for turnover, are no more. Today, we encourage pump run times for two simple reasons - surface skimming and chemical maintenance (i.e. SWG production, mixing chemicals, etc). If your VSP also powers a cleaner, then that would also apply, but that's really it. So the run time will vary drastically by pool type, method of chlorination, local conditions, etc. What I would recommend is setting your pump with a very basic run time of about 8 hours at a low rpm. If you need to program it to a higher rpm for a short period to purge air bubbles once or twice a day that's fine. Your signature is not updated so we can't see all of your equipment, but if you have an SWG, monitor FC production. Also monitor how well the pump skims debris off the water's surface. From there, you can adjust run time up or down as needed.

 
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ron_jeremy

Member
May 5, 2016
24
CA
Hi @Texas Splash thx for offering to help. I just installed the new motor for a family member that lives in the greater Los Angeles area. The motor feeds a chlorine pool (not salt water) and they also use a robo cleaner vac (I believe it's called "The Pool Cleaner"). When you say to run the pump for 8 hours at a "low rpm" what would you suggest? I don't know if by "low rpm" you mean 600 rpm, 1200 rpm, 1800 rpm, or something else entirely. This is the source of my frustration. I think I might just install a flow rate meter and make calcs based on that but before doing that I'd sure love to get some kind of ballpark " x hours @ x rpm" guidance.
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2014
33,887
Texas, San Antonio/Marion, South-Central Area
Pool Size
17888
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
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When you say to run the pump for 8 hours at a "low rpm" what would you suggest?
I was referring to a relatively low rpm like about 1,200 just for general water movement and surface skimming. You would probably need a higher rpm for times when the "Pool Cleaner" is being used. That higher rpm could vary depending on how much suction/pressure the cleaner requires for good movement. I'll poke @Jimrahbe for his thoughts. :)
 

mguzzy

Gold Supporter
It seems to me most people that get VS pumps just end up running them 24/7 since they pull so little power and then they adjust the speed up notch by notch until it provides the desired results, like run you water feature, turn on the SWG flow switch, skim your crud.... Its not very scientific but it seems to work ;)
 

ron_jeremy

Member
May 5, 2016
24
CA
Thanks for the input @Texas Splash and @mguzzy .

I'm going to make an assumption that the new 2.7HP vs motor will move about 80 gal per minute at full speed 3450 rpm. Based on my assumption, here's what I'm thinking (the values have been rounded):

RPMGPMGPHHOURSGAL PER 24 HOURS
345080480000
300069.5417028340
200046.42784411136
100023.2185647424

At 26,900 gallons, this would filter the pool just over once per day. Do the above numbers look right? Also, the pool is not used very often.

Thoughts?
 
Last edited:

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
14,826
Pleasanton, CA
Pool Size
20000
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Plaster
Chlorine
Salt Water Generator
You still seem to be focused on turnovers. The number of gallons pumped in a 24 hour period is totally irrelevant.

What is it you are really trying to accomplish with all this?
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
23,595
Bedford, TX
Ron,

You need to move into this Century and quit believing in the Big Turnover Myth.

My IntelliFlo runs at 1200 RPM most of the time.. This is because it takes about 1100 RPM to turn on my flow switch in the SWCG. So I run at 1200, just to make sure..

I have waterfall wall that takes 2800 RPM to make it look right.. I hardly ever run it, except for 15 minutes just to keep the pipes flushed.

To help skim I run a hour at 1500, twice a day..

Just adjust your speeds to match how your pool works and what you want it to do.. Not some magic chart.

Thanks,

Jim R.
 
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mas985

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May 3, 2007
14,826
Pleasanton, CA
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Hey @mas985 thanks for the input. I'm trying to calculate how long the pump needs to run & at what rpm(s) so the pool is correctly filtered.
Filtering does nothing for sanitation. Only chlorine is necessary for sanitation. Filtering is merely an aesthetic task, it just makes the pool look better. But one thing to keep in mind is that most debris in a pool either sinks or floats. Any very tiny particles that are suspended in the pool cannot be filtered anyway as it is usually much smaller than what a pool filter can remove. So to remove the debris in a pool that you can, you should either run a pool cleaner to remove the debris sitting on the bottom of the pool or run the pool skimmers to remove debris on the surface of the pool. Attempting to remove suspended particles is a waste of time and energy. It just can't be done effectively. But it isn't necessary either. Only chlorine is necessary.

So the simple answer to your question on run time is to run the pump long enough so that the pool looks as clean as you want. This is no magical number and can be as short as you want it. Again, it just about personal preference and not sanitation.

As for speed, to save energy, use the lowest RPM possible that is sufficient so that your skimmers are collecting debris. This min speed is usually when the water is running over the weir door instead of around it.
 
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ron_jeremy

Member
May 5, 2016
24
CA
Ron,

My IntelliFlo runs at 1200 RPM most of the time...

To help skim I run a hour at 1500, twice a day..

Just adjust your speeds to match how your pool works and what you want it to do.. Not some magic chart.

Thanks,

Jim R.

So the simple answer to your question on run time is to run the pump long enough so that the pool looks as clean as you want. This is no magical number and can be as short as you want it. Again, it just about personal preference and not sanitation.

As for speed, to save energy, use the lowest RPM possible that is sufficient so that your skimmers are collecting debris. This min speed is usually when the water is running over the weir door instead of around it.
Thank you so much @Jimrahbe and @mas985 for continuiing to help.

@Jimrahbe you say you run your setup at 1200 RPM "most of the time" and @mas985 you mentinoed to use the "lowest speed pssobile". Ok, I can now finally wrap my head around what you're suggesting.

Just curious, do you both run your VS motors 24-hours per day?
 

mas985

TFP Expert
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May 3, 2007
14,826
Pleasanton, CA
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Salt Water Generator
I do not run 24 hrs per day. I have very high electrical costs so 24 hr is a big bump in costs. In the summer, I run at about 1500 RPM, I have two skimmers which requires more flow rate, and for about 9 hrs per day, mainly for solar gain. In the winter, I run only two hours per day at the same 1500 RPM.
 
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Jimrahbe

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Jul 7, 2014
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Ron,

I do run 24/7, but it is because I like generating a little chlorine all the time and I like skimming all the time.

I have three pools and they all run pretty much the same routine.. Each pool has a 3 HP IntelliFlo VS pump.

Just to be clear.. We are not trying to tell you how long, or at what speed, to run your pump.. We are trying to tell you, that you need to run your pump for a real reason... not some myth about turnovers..

If I had a single speed pump, I would set my SWCG to 100% output and run the pump the shortest period of time that would make the chlorine my pool needs.. But, since I have a VS pump, it is best (for me) to run my SWCG at a low output, and run the pump as long as possible. In my case running 24/7 costs me less than $20 bucks a month..

Each pool is a little different. My pools skim well at 1200 RPM, but if my pool had a heater, I'd probably have to run 1500 or so.

You just need to run a speed that accomplishes your goals.. If you are using a tab feeder, (shudder.. :mrgreen: ) you will have to run long enough, and with enough flow, to dissolve the tablets. If you have a SWCG, you will have to run fast enough to turn on your SWCG's flow switch, and long enough for the SWCG to make the chlorine your pool needs. The more junk you have floating on top of the water the more you "might" want to run the pump to keep the surface clean.. on the other hand some people don't care about skimming when they are not using the pool.. Pools and people are different and their needs dictate the speed and length of time the pump runs..

Play with it, you can't hurt anything.

Thanks,

Jim R.
 
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Rich807

Bronze Supporter
Jun 21, 2020
125
Las Vegas, NV
If you don’t have a swg run the rpm only enough to get water flowing over the top of the skimmer weir door. Take things from there if you need more skimming power.

Thanks to the folks here I now let mine run 24/7 @ around 1450rpm as I have a heater so that’s what it takes to push enough water pressure through my system pipes in order to pull the weir door down enough to get water going over the top of it. Guys here helped me figure out it only cost $20 or less a month to just leave the pump running. Less wear/tear heat-cycling etc = works for me.
 

ron_jeremy

Member
May 5, 2016
24
CA
Thanks all for your help. The V-Green motor has a wattage meter on it but I'm currently not at my family's place to play with the settings. Do any of you know whether the watts used vs RPM is linear? For example, does 1500 RPM use half the watts vs 3000 RPM?
 

Jimrahbe

Mod Squad
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Jul 7, 2014
23,595
Bedford, TX
Ron,

Not linear at all... it is a curve.. Going from say 3000 RPM to 3450 almost doubles the power used.

At 1200 RPM, where I run most of the time, my 3 HP IntelliFlo only uses about 180 watts...

I think that @PoolGate has a great breakdown as an example... If we can wake him up.. :mrgreen:

Thanks,

Jim R.
 
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Newdude

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Jun 16, 2019
11,614
NY
I have three pools and they all run pretty much the same routine.. Each pool has a 3 HP IntelliFlo VS pump
This never gets seen with the gravity it deserves so I’m gonna point it out again. Sure Jim looks at his own pool 24/7 and is there to tweak it, but the other 2 just sit there maintaining themselves. He shows up once a week for some *minor* tweaks and pays it no mind for the next 7 days. He has effectively hacked the system and corrected everything that is wrong with the misguided once a week pool service industry. He is his own pool boy who shows up once a week for a half hour but the difference is that Jim’s way works.

You can split hairs that he can reduce his costs by 1/3 running only 16 hours a day, or 1/2 by running 12 hours, but at $20 a month does anybody really care about $6-$10 for the total piece of mind it brings ?

One ooops being too frugal will erase 2 years worth of both minimal cost and effort.
 

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