Which moves more water....
- Thread starter Philo
- Start date
- May 3, 2007
- 18,129
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
First, HP and RPM are not linear relationships. Second, it depends on the pumps you are comparing. Can you be more specific about the VS pumps you are comparing?
Comparing these two pumps:
TriStar VS 950 HL32950VSP @ 1500 RPM = 42 GPM
TriStar VS 900 HL32900VSP @ 3000 RPM = 74.2 GPM
Not even close although the VS900 is not exactly 1/2 the THP of the 950. It is hard to find a pump pair with exactly 2:1 THP.
But if you could find a 2:1 ratio, the lower THP will probably always move more water because of the relationship between THP and RPM.
The advantages of a higher THP are lower RPM for a given GPM and usually lower energy usage too. So the larger pump is going to be more quite.
Comparing these two pumps:
TriStar VS 950 HL32950VSP @ 1500 RPM = 42 GPM
TriStar VS 900 HL32900VSP @ 3000 RPM = 74.2 GPM
Not even close although the VS900 is not exactly 1/2 the THP of the 950. It is hard to find a pump pair with exactly 2:1 THP.
But if you could find a 2:1 ratio, the lower THP will probably always move more water because of the relationship between THP and RPM.
The advantages of a higher THP are lower RPM for a given GPM and usually lower energy usage too. So the larger pump is going to be more quite.
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Phil,
The whole point about getting a VS pump is so that you can run it slowly.. The bigger pumps move more water at a slower speed.
The only downside to buying a large VS pump is the initial cost..
I have three pools that all have 3 HP IntelliFlo pumps.. If I had to do it all over again, I would still make the same decision..
In my mind, the IntelliFlo is the Gold Standard of VS pumps.
Thanks,
Jim R.
The whole point about getting a VS pump is so that you can run it slowly.. The bigger pumps move more water at a slower speed.
The only downside to buying a large VS pump is the initial cost..
I have three pools that all have 3 HP IntelliFlo pumps.. If I had to do it all over again, I would still make the same decision..
In my mind, the IntelliFlo is the Gold Standard of VS pumps.
Thanks,
Jim R.
I just helped a neighbor put an IntelliFlo 3hp pump in. What a difference vs. 1.5hp.
The 3hp says 100 watts at 1200RPM which triggers the flow switch just fine.
The 3hp says 100 watts at 1200RPM which triggers the flow switch just fine.
- May 3, 2007
- 18,129
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
Comparing the Intelliflo with the Blue Torrent:
Intelliflo @ 1500 RPM, 43 GPM, 278 Watts
Blue Torrent NWC15VSG @ 3000 RPM, 51 GPM, 701 Watts
At the same flow rate and on the same plumbing, which is the way pumps should be compared:
Intelliflo @ 1775 RPM, 51 GPM, 426 Watts
Blue Torrent NWC15VSG @ 3000 RPM, 51 GPM, 701 Watts
That is a bigger difference than I would have expected at the same flow rate.
Note too that the Intelliflo is actually a 3.96 THP motor.
Intelliflo @ 1500 RPM, 43 GPM, 278 Watts
Blue Torrent NWC15VSG @ 3000 RPM, 51 GPM, 701 Watts
At the same flow rate and on the same plumbing, which is the way pumps should be compared:
Intelliflo @ 1775 RPM, 51 GPM, 426 Watts
Blue Torrent NWC15VSG @ 3000 RPM, 51 GPM, 701 Watts
That is a bigger difference than I would have expected at the same flow rate.
Note too that the Intelliflo is actually a 3.96 THP motor.
It seems like Pentair keeps increasing the rated hp of the Intelliflo.
I think that it used to be 3.0 then 3.45, now it's 3.95.
The website says 3.95, but the manual says:
Input: 230 VAC, 50/60 Hz, 3200 Watts Maximum, 1 phase, which is 4.29 hp input.
The rated hp is usually significantly less than the input hp.
So, the 3.95 seems like a stretch.
- May 3, 2007
- 18,129
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
The Intelliflo motor is supposed to be 92% efficient (as advertised) at full speed so pretty close to that ratio (3.95/4.29=0.92075).
Forgot to mention that a 4 HP induction motor can get better than 85% efficiency so in reality, the PM motor is not that much better.
Forgot to mention that a 4 HP induction motor can get better than 85% efficiency so in reality, the PM motor is not that much better.
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The largest WhisperFlo single speed is listed as 3.45 hp.
It is essentially the same pump with the same impeller.
At 3,450 rpm, it seems like the output hp would be the same.
It is essentially the same pump with the same impeller.
At 3,450 rpm, it seems like the output hp would be the same.
- May 3, 2007
- 18,129
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
The required shaft BHP is the same. However, when it comes to ratings, that really doesn't matter all that much. It is about maximum current for a given thermal load that determines the THP rating. The Intelliflo motor may just be "rated" a little bigger but it doesn't mean that it ever operates at that level. There is also a 10% variance allowed in the ratings.
Ok.
It seems to me that Pentair likes to exaggerate the hp a little bit to seem like they have a better or stronger pump.
Pretty soon, the rated hp will be 4.0 or higher.
I suppose that they have enough room to make whatever claim they want.
It seems to me that Pentair likes to exaggerate the hp a little bit to seem like they have a better or stronger pump.
Pretty soon, the rated hp will be 4.0 or higher.
I suppose that they have enough room to make whatever claim they want.
- May 3, 2007
- 18,129
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
If you look at the Intelliflo XF, if has a THP of 3.96 as well so perhaps the motor is the same and just the wet end is different. If you look at the Whisperflo XF, it has a THP of 3.45 as well. However, when you look at the input wattage, the Intelliflo XF uses 2837 Watts on Curve-C while the Whisperflo XF uses 3075 watts or about 8% higher which would indicate an 8% difference in efficiency which would make the Whisperflo motor about 84% efficient which is consistent with what I have seen for induction motors. If you work backwards to BHP, both would have a BHP of 3.444 which is below the Whisperflo motor rating.
The best way to compare two pumps like that is to graph the performance curve of each pump and the system curve on the same graph.
https://aquamagazine.com/service/how-to-read-pump-system-curves.html
If you look at the IntelliFlo at 1,500 rpm, you get about 29 gpm.
If you look at the SuperFlo at 3,000 rpm, you get about 52 gpm.
The IntelliFlo is about 2 X the total horsepower of the SuperFlo VS (depending on how the HP is defined).
To get to about 52 gpm on the Intelliflo (On this system curve), you would need to run the pump at about 2,540 rpm.
So, you can't just look at the hp and the rpm.
You need to account for the system and the pump performance curve and you need to know the power used at each flow rate.
Overall, I would choose a variable speed pump that can meet your flow requirements at a speed below 2,750 rpm due to the noise at speeds above 2,750 rpm.
In general, the difference in power usage (at the same flow rate and the same system) between the smaller pump and the bigger pump is not enough to matter.
In general, the bigger pump will be much quieter and that is what I would recommend.
If you can meet your flow needs with a SuperFlo VS at 2,400 rpm, or less, then that is not a bad choice.
In general, the bigger pump will be much quieter and that is what I would recommend.
If you can meet your flow needs with a SuperFlo VS at 2,400 rpm, or less, then that is not a bad choice.
In your opinion, what should the rated total hp for the IntelliFlo VS be?
Is the 3.95 number reasonable, or should it be 3.45, or something else?
Manufacturers should be able to provide a performance curve with the best efficiency range marked.
You always want the system curve to cross the pump performance curve in the best efficiency range.
You almost never want to choose a pump where the system curve crosses the pump performance curve outside of the indicated best efficiency range.
As you can see in this graph, pump C has a small range for efficiency and you might need to go outside of the range.
In any case, single speed pumps are mostly obsolete and most pumps will be variable speed.
For the most part, you want your system curve to go through the middle 60% of the pump performance curve and avoid the ends of the curve.
As long as the system curve crosses the pump performance curve at at least 10% of the length of the pump performance curve away from the ends, it is probably ok.
You always want the system curve to cross the pump performance curve in the best efficiency range.
You almost never want to choose a pump where the system curve crosses the pump performance curve outside of the indicated best efficiency range.
As you can see in this graph, pump C has a small range for efficiency and you might need to go outside of the range.
In any case, single speed pumps are mostly obsolete and most pumps will be variable speed.
For the most part, you want your system curve to go through the middle 60% of the pump performance curve and avoid the ends of the curve.
As long as the system curve crosses the pump performance curve at at least 10% of the length of the pump performance curve away from the ends, it is probably ok.
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- May 3, 2007
- 18,129
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
Technically, the rating is for the motor and not the pump although most people treat them the same. The only real requirement is that the pump maximum BHP, over the entire head curve, needs to be less than or equal to the motor THP rating. So the Intelliflo motor may indeed be rated for 3.95 and the pump maximum BHP may only be 3.45 and there is nothing wrong with that. They are really two separate things that just need to be taken into account when matching a motor to a pump. In fact, most pump maximum BHP are probably less than the THP of the motor. That is preferable to keep temperatures to a minimum.
The pump and motor are really two separate machines and the ratings should be separate as well. Ideally, the pump impeller should have a maximum BHP rating and separately, the motor should have a maximum THP rating. Unfortunately, the way impeller's are rated are a bit ambiguous. The typically have a full rated HP which is less than the true maximum BHP which is in line with the motor the pump uses. So it is rated as if it was put on a specific motor with a specific SF which is not always the case (i.e. up rated motor). This is not a great way to identify the impeller rating. However, with the DOE rules, this issue will slowly fade away with single/two speed pumps fading away.
Here is a good example of how confusing pump labels can be.
The SHPF.75 and the SHPM1.0 pumps are the exact same pump.
The SHPF is sold as a 0.75 hp “Full” rated pump.
The SHPM1.0 is sold as a 1.0 hp “Max” rated pump.
The “F” stands for “Full” and the “M” stands for “Max”.
The total hp is listed as 1.25 hp.
So, is the pump a 3/4 hp pump, a 1 hp pump or a 1.25 hp pump?
It’s really very confusing.
www.jandy.com
That’s why you need to be able to see the system curve graphed on the pump performance curves for different pumps or for a variable speed pump at different speeds.
The SHPM1.0 has 1.25 total hp and uses 5.6 amps.
The SHPM2.5 has a total of 2.6 hp and uses 10 amps.
The SHPM1.0 gets about 75 gpm on this system curve (Curve C) and the SHPM2.5 gets about 95 gpm on the same curve.
So, even though you are doubling the power, the flow is only marginally better.
The SHPF.75 and the SHPM1.0 pumps are the exact same pump.
The SHPF is sold as a 0.75 hp “Full” rated pump.
The SHPM1.0 is sold as a 1.0 hp “Max” rated pump.
The “F” stands for “Full” and the “M” stands for “Max”.
The total hp is listed as 1.25 hp.
So, is the pump a 3/4 hp pump, a 1 hp pump or a 1.25 hp pump?
It’s really very confusing.
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That’s why you need to be able to see the system curve graphed on the pump performance curves for different pumps or for a variable speed pump at different speeds.
The SHPM1.0 has 1.25 total hp and uses 5.6 amps.
The SHPM2.5 has a total of 2.6 hp and uses 10 amps.
The SHPM1.0 gets about 75 gpm on this system curve (Curve C) and the SHPM2.5 gets about 95 gpm on the same curve.
So, even though you are doubling the power, the flow is only marginally better.
- .5, .75, 1.0, 1.5, 2.0, 2.5, 3.0, 5.0 HP Models available.
- May 3, 2007
- 18,129
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
Sometimes I get Vuja De, which is the unsettling feeling that none of this has ever happened before.
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