GPM vs. RPM issue - Pentair Intellicenter

MCF50

Well-known member
Aug 18, 2020
241
Houston
I have noticed the last week or so using our hot tub the flow was about 65gpm. Today I tried to adjust the flow on the app to 75 and it wouldn't go above about 65-66gpm. I check settings for pump and max flow is set to 100 and max rpm set to 3450rpm. After several tries I switched from GPM to RPM. adjust RPM for around 2000 to 3000rpm and just like it should, flowrate went up to 73gpm. Bumped rpm to 3250 and gpm got and held at 78gpm. Curious as to why adjusting gpm wouldn't make it increase but increasing rpm did.
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
20,892
Bedford, TX
50,

I can't think of any reason to run GPM.. Almost no one needs it..

But.. to directly answer your question I have no idea... Let's see if @JamesW knows...

Thanks,

Jim R.
 

JamesW

TFP Expert
Mar 2, 2011
23,356
Probably the psi limit in Settings.

You have to check from the pump keypad.

If you have automation, put it in Service mode and check the pressure limit.

 

JamesW

TFP Expert
Mar 2, 2011
23,356
The maximum system pressure is set to 30 psi as a default. The pressure is estimated by the pump from the power usage and is probably not super reliable under all conditions.

You can change the pressure limit. You should make sure that the filter is clean and not creating excessive pressure.

The system pressure as shown on the pump display includes the suction and return pressure. So, it won’t necessarily match the filter pressure.

If the pump system pressure from the display is significantly higher than the filter pressure, the suction might be too small or have some sort of restriction like a clog.

What are the pump system pressure from the pump display and the filter pressure at different speeds and flow rates?

Max Pressure (1-50 PSI) - Default: 30 PSI

_____________________________________________________________________________________

To Set Maximum System Pressure:

1. Check that the green power LED is on.

2. Press Menu.

3. Press Select to select “Settings”.

4. Use the Up or Down arrows to scroll to “Min/Max”. Press Select.

5. Use the Up or Down arrows to scroll to “Set Maximum Pressure”.

6. Press Select to change the setting. The cursor will appear in the first number column (ones).

7. Press the Up or Down arrows to edit the maximum flow rate setting from 1 to 50 PSI.

8. Press Save to save. To cancel, press Back to exit edit mode without saving.

9. Press Back to exit.

_____________________________________________________________________________________

Set Pressure Limit for Speed Program

While Pressure Limit is active whenever the pump is operating a Flow type of program, the pressure limit is disabled by default when running the pump in a constant speed mode. Enabling this feature will make sure that the drive is monitoring the system pressure when operating in constant speed mode also.

1. Check that the green power LED is on.

2. Press Menu.

3. Press Select to select “Settings”.

4. Use the Up or Down arrows to scroll to “Min/Max”. Press Select.

5. Use the Up or Down arrows to scroll to “Press Limit (Speed)”.

6. Press Select to move the cursor over the "Disabled".

7. Press and the Up or Down arrows to change it to "Enabled".

8. Press Save to save. To cancel, press Back to exit edit mode without saving.

9. Press Back to exit

 

MCF50

Well-known member
Aug 18, 2020
241
Houston
I have a Pentair VFD pump for hot tub. I typically adjust flowrate to around 75gpm and have no issues. Yesterday I was heating it up and flowrate wouldn't get above ~62gpm by adjusting flowrate. I have Pentair Intellicenter. So I switched to RPM and increased the rpm and flowrate went up. About 3250rpm got to 75gpm. So I left setting at 3250rpm. Started spa today (VERY COLD AMBIENT AND WATER) at 3250rpm and flowrate is holding at about 70rpm. Is this due to the cold ambient (35F) and water. Checked settings and pump max rpm is 3400 and pump max flow is 100gpm. I know you can only get about 75gpm thru 2" pipe. Thanks!
 

JamesW

TFP Expert
Mar 2, 2011
23,356
You should keep your posts in the same thread when the topics are related.


Did you check the pressure limit as suggested in the other thread?

The filter pressure and the suction configuration will affect the gpm for a particular RPM.

Also, the flowrate shown by the pump is estimated and it is probably not super accurate.

If it's within 5 gpm, I suspect that the resolution is not good enough to distinguish a 5 gpm difference with any certainty.
 

MCF50

Well-known member
Aug 18, 2020
241
Houston
Thanks guys.....for some reason I cannot see anything on my pumps display. I cannot get to the pump right now, but when I do I'll take a pic. I think my PB set it up so any adjustments have to be made in the control panel.
 

JamesW

TFP Expert
Mar 2, 2011
23,356
Sorry..forgot I posted this already. Let me check it out. How do you check pressure limit?
The other thread responses show how to check the pressure reported by the pump and how to adjust the pressure limits.
 

Enjoying this content?

Support TFP with a donation.

Give Support

MCF50

Well-known member
Aug 18, 2020
241
Houston
50,

I can't think of any reason to run GPM.. Almost no one needs it..

But.. to directly answer your question I have no idea... Let's see if @JamesW knows...

Thanks,

Jim R.
The reason I run GPM is so I can see flowrate. If I set the pool/bubbler/spa pump at 2000rpm, I have no idea what flowrate is coming out. I prefer GPM over RPM I guess.
 

JamesW

TFP Expert
Mar 2, 2011
23,356
You have to put the automation into "Service" mode to be able to control the pump from the pump display.
 
  • Like
Reactions: MCF50

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
20,892
Bedford, TX
If I set the pool/bubbler/spa pump at 2000rpm, I have no idea what flowrate is coming out. I prefer GPM over RPM I guess.

50,

It is your pool and you can run it any darn way you want... :mrgreen:

That said, why do you care what the flow rate is.

Thanks,

Jim R.
 

MCF50

Well-known member
Aug 18, 2020
241
Houston
Because when I am in the hot tub I want the max flow coming out returns. Because when pool is circulating water during the day I care about how many gallons per minute are being circulate not how many times the pump is turning per minute. Hmmm. Does that make any sense? Never seen a recommendation of how many revolutions a pool pump should do a day. Hmmm
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
20,892
Bedford, TX
50,

Sounds like you must still believe in the "X Turnover per day" myth... It is just not true.. Your pool stays clear because of the chemicals in the water, not the number of times your water passes through the filter. The filter is there to capture the things that fall into your pool...

We have some people here that only run their pump for a couple of hours a day and others, like me, that run their pump 24/7.. I run mine at a low RPM so that I get constant generation of chlorine and constant skimming.. I don't care, or even know, how may turnovers (if any) I get per day.

Like I said.. it is your pool and your should do what you want. I'm just trying to make sure you have all the facts..

Thanks,

Jim R.
 
  • Like
Reactions: MCF50

Flying Tivo

Well-known member
Jan 24, 2017
1,991
Monterrey, NL, Mexico
No sense at all! Those 2 lines or thinking are a myth. Pool water volume does not need turning over. Chemistry is what matters. Rpms creat flow, so they are directly proportional.
 

MCF50

Well-known member
Aug 18, 2020
241
Houston
So if Im in my hot tub and I want to make sure I am getting the maximum possible flow out of returns (~75gpm) I guess I should just put pump speed at 3450rpm? No, because of variations (i.e. filter back pressure) increasing speed may or may not result in the desired flow and end up stonewalling the pump at a maximum speed without getting additional flow - wasting power amd wearing out pump faster. With regards to turning water over, I think it's just a little nasty to let water sit stagnant. But that's just me.
 

MCF50

Well-known member
Aug 18, 2020
241
Houston
50,

Sounds like you must still believe in the "X Turnover per day" myth... It is just not true.. Your pool stays clear because of the chemicals in the water, not the number of times your water passes through the filter. The filter is there to capture the things that fall into your pool...

We have some people here that only run their pump for a couple of hours a day and others, like me, that run their pump 24/7.. I run mine at a low RPM so that I get constant generation of chlorine and constant skimming.. I don't care, or even know, how may turnovers (if any) I get per day.

Like I said.. it is your pool and your should do what you want. I'm just trying to make sure you have all the facts..

Thanks,

Jim R.
Thanks. I don't believe in X turnovers per day, but I do like to have at least one so I run my pump at 45gpm for 2 4.5 hour windows. Keeps stuff from floating around - enough to utilize the skimmer and filter out stuff that falls into the pool - like maybe bird Darn. For those that don't run their pumps at all, think about that.....I wouldn't want bird Darn sitting in stagnant water. Thats gross.
 

MCF50

Well-known member
Aug 18, 2020
241
Houston
You should keep your posts in the same thread when the topics are related.


Did you check the pressure limit as suggested in the other thread?

The filter pressure and the suction configuration will affect the gpm for a particular RPM.

Also, the flowrate shown by the pump is estimated and it is probably not super accurate.

If it's within 5 gpm, I suspect that the resolution is not good enough to distinguish a 5 gpm difference with any certainty.
I believe I found the issue...at the high pump SPEED the filter differential is close to 30psi. Time to clean the filter.
 

Enjoying this content?

Support TFP with a donation.

Give Support
Thread Status
Hello , There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.