chem geek that chart you posted is a great help. I was also wondering about if there would be cost savings for a super slow 24 hr turn. Looks like the 11 hour 750 RPM speed will be the cheapest for me. I may also set a program to kick the speed up when the pool cleaner comes on although it has its own booster pump. Now that I think about it there is probably no benefit up increasing the pump speed when the legend pool cleaner comes on...
Intelliflow Flow Rate and Run Time
- Thread starter TheOne
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With 15,250 gallons, one turnover in 24 hours is 15,250/24/60 = 10.6 GPM. As you could see from the table, that sort of flow rate uses more total energy because of the fixed (constant) energy used even when the pump is not spinning at all. That is, there are fixed energy costs of around 80 Watts for the resistive losses in the wiring and the other electronics (or so I would assume that's where these losses are). So you have to run the pump fast enough to have a flow rate that makes up for these losses (by shortening total run time), but not so fast as where the frictional losses from the piping come into play (at higher flow rates). That's why the sweet spot is at higher flow rates of 23-30 GPM. Only if there were no such fixed losses would it make sense to run the pump as slow as possible, but it appears that is not the case for this (or probably for any other variable speed) pump.
I don't think you will even be able to do a super-slow 24 hour turn since you said the pump will only go down to 400 RPM anyway.
The calculations I did actually don't depend on the specific system curve (i.e. piping length or size) unless the system is far away from the efficiency points on the pump curves and those are rather broad. But again, this is all theory based on Pentair info and the only way to know for certain is to measure your electrical usage with your real pump on your real system vs. flow rates.
One final point to make is that I assumed that the 80 Watts that appear to be consumed by the pump independent of RPM is something that goes away when the pump is turned off by the controller (i.e. put into standby mode, if it has such a thing). If instead the pump is drawing 80 Watts all the time even when it isn't running, then my assumptions would be wrong and you should use the lowest RPM for most efficiency so should run all the time (i.e. 24 hours). However, in practice the slowest pump speed allowed is apparently 400 RPM so that is the real limit for most pools. It should be easy to have the pump off from the controller, measure the electrical usage, then unplug the pump (or turn off the circuit breaker to it) and measure electrical usage again. This would be useful info.
I don't think you will even be able to do a super-slow 24 hour turn since you said the pump will only go down to 400 RPM anyway.
The calculations I did actually don't depend on the specific system curve (i.e. piping length or size) unless the system is far away from the efficiency points on the pump curves and those are rather broad. But again, this is all theory based on Pentair info and the only way to know for certain is to measure your electrical usage with your real pump on your real system vs. flow rates.
One final point to make is that I assumed that the 80 Watts that appear to be consumed by the pump independent of RPM is something that goes away when the pump is turned off by the controller (i.e. put into standby mode, if it has such a thing). If instead the pump is drawing 80 Watts all the time even when it isn't running, then my assumptions would be wrong and you should use the lowest RPM for most efficiency so should run all the time (i.e. 24 hours). However, in practice the slowest pump speed allowed is apparently 400 RPM so that is the real limit for most pools. It should be easy to have the pump off from the controller, measure the electrical usage, then unplug the pump (or turn off the circuit breaker to it) and measure electrical usage again. This would be useful info.
I installed a flow meter and was able to get some good data on RPM/GPM for my system.
For my 15250 gallon pool a 12 hour turn is just over 21 gpm. I tested that my pump needs to run at 1650 RPM to give 21 GPM.
My SWCG looks like it will run as low as 16 GPM. If I set my pump to run slower that 16 GPM I get a "No Flow" warning on the salt cell and it disables chlorine production.
Another interesting note is that I gain 2 GPM @ 1650 RPM just by diverting some of my return flow to the spa. I currently have my return valve set at 70%/30% split between the pool and spa. If I set the valve to 100% pool I lose about 2 GPM at 1650 rpm and 15+ GPM at 3430 rpm.
Also I noted there is a drop in GPM if I change my suction side valve to 100 % main drain. I can get higher GPM's at the same rpm just by changing the suction to pull more from the skimmers. I normally have my suction valve at about 70% skimmers and 30% main drain.
So the optimum valve setting (for my pool) for GPM flow looks to be 30% or less main drain suction and the rest skimmer and 30% return to spa and 70% to pool.
Now if I can figure out how to read my electrical meter I can put some kwh to each RPM level.
Oh when I floored the pump to 3430 rpm my flow meter pegged at about 80 gpm. Thats as high as my flow meter will go. The pool water looks like a water park with so much action at that rpm.
For my 15250 gallon pool a 12 hour turn is just over 21 gpm. I tested that my pump needs to run at 1650 RPM to give 21 GPM.
My SWCG looks like it will run as low as 16 GPM. If I set my pump to run slower that 16 GPM I get a "No Flow" warning on the salt cell and it disables chlorine production.
Another interesting note is that I gain 2 GPM @ 1650 RPM just by diverting some of my return flow to the spa. I currently have my return valve set at 70%/30% split between the pool and spa. If I set the valve to 100% pool I lose about 2 GPM at 1650 rpm and 15+ GPM at 3430 rpm.
Also I noted there is a drop in GPM if I change my suction side valve to 100 % main drain. I can get higher GPM's at the same rpm just by changing the suction to pull more from the skimmers. I normally have my suction valve at about 70% skimmers and 30% main drain.
So the optimum valve setting (for my pool) for GPM flow looks to be 30% or less main drain suction and the rest skimmer and 30% return to spa and 70% to pool.
Now if I can figure out how to read my electrical meter I can put some kwh to each RPM level.
Oh when I floored the pump to 3430 rpm my flow meter pegged at about 80 gpm. Thats as high as my flow meter will go. The pool water looks like a water park with so much action at that rpm.
My flow meter was mfr by Blue-White. Its called a Pitot tube insertion meter. Its the clamp on type. I can post pix and installation if there is any interest.
I would like to see a picture if possible of the installation. Did you buy it directly from Blue-White?
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