I agree, and my thread made that pretty clear.
In any case, Hayward is the one making the label, so you have to ask them about why they choose to do things that way when it is confusing and it will lead people to make bad choices.
Impeller Ratings
- Thread starter Zurak
- Start date
In any case, Hayward is the one making the label, so you have to ask them about why they choose to do things that way when it is confusing and it will lead people to make bad choices.
- May 3, 2007
- 18,067
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
This type of identification is not unique to Hayward. Pretty much all manufactures use this same type of labeling. Much like a motor nameplate HP (pre-DOE), the impeller HP labeling is not the same as THP and it is just important to remember that.
Why did they do it this way? You could ask the same thing about motor nameplate HP. It is basically the same thing and probably why they chose to do the same with impellers. It is mostly historical convention from applications where motors basically were run under two different loads (with and without SF). This of course does not apply to pool pump motors where the load is fairly constant with RPM (except for valve changes).
But if you look at the part# for the label, it is similar to the pump model#. In this case, the SPX3215C is the correct impeller for the following pump models:
Full Rated Versions (1.5HP Nameplate HP)
TriStar SP32152EE
TriStar SP3215EE
Up Rated Versions (2.0HP Nameplate HP)
TriStar SP3215X20
TriStar SP3215X202
TriStar SP3215X202BH
Note how the number 3215 is in all the part #s. The up rated versions will have a lower SF motor than the full rated versions. But the head curves for all these pump models are identical because the impellers are identical.
That was the reason that I wrote the thread about Eliminating the Service Factor and shortly thereafter, they eliminated the Service Factor, mostly due to my thread (In my opinion).
In any case, now they have something called WEF (Which stands for Worthless Efficiency Factor), which is even dumber than Service Factor.
Apparently, they need at least 1 idiotic metric that they can use to baffle and confuse the world with.
Last edited:
Service factor yes, impeller no. I will let everyone know what Hayward has to say
Your examples show that SPX3215C is the correct impeller for the motors/pumps you listed, but not what the actual impeller HP rating is.
The Hayward packaging for the SPX3215C states it's a 1-1/2 HP impeller, yet websites change the description which is confusing. If the actual impeller HP rating is different than what Hayward states on their packaging then it is even more confusing and hence my question.
The Service Factor is what caused the problem in the first place.
A 1.0 H.P pump with a 1.65 SF and a 1.5 HP pump with a 1.1 SF are the same pump but one is labeled as a 1.0 hp pump and the other is labeled as a 1.5 hp pump even though they are both 1.65 total hp pumps.
So, the impeller might be labeled as going to a 1.0 hp or a 1.5 hp or a 1.65 hp pump.
You are correct that the ratings are confusing and misleading.
I suspect that Hayward will not have any sort of satisfactory answer for the issue.
There is a 99.9% probability that the person who responds won't have any idea what you are asking about.
- May 3, 2007
- 18,067
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
That is because unlike a motor, an impeller really does not have a maximum rating. The load that a particular impeller imparts upon the motor is a function of RPM, head curve operating point and is often called braking HP or BHP. The only thing that we can say for sure is that the BHP of the impeller is less than or equal to the THP of the motor at full speed by design. This probably why THP is not used for impellers.
Note too the impellers are not interchangeable between pump lines. That particular impeller will ONLY work on the TriStar pump line wet ends and ONLY for those pump models that it was originally targeted for (i.e. motor THP). However, a motor can be used for many different pump lines and impellers so a maximum rating is much more important.
I think you are still stuck on a single definition of HP. Again label/nameplate HP is not the same as THP. The only thing that matters on that label is part #. You can then use that to determine which pumps that impeller works with as I pointed out above.
There are many definitions of HP
- Nameplate HP (NPHP) - This is the HP rating on the motor nameplate but is pretty much meaningless without the service factor.
- Full Rated HP (FRHP) - Similar to nameplate HP and sometimes used when the pump is full rated.
- Up Rated HP (URHP) - Similar to nameplate HP and sometimes used when the pump is max rated or up rated.
- Total HP (THP) or Service Factor HP (SFHP) = NPHP * Service Factor. This is the maximum load that can be safely driven by the motor and must always be greater than the maximum load from the impeller. A motor can be driven above the THP but will likely fail in a short period of time.
- Electrical Horsepower (EHP) = Input Watts / 745.7 = Volts * Amps * Power Factor / 745.7 - Electrical power input delivered to the motor.
- Brake Horsepower (BHP) = EHP * Motor Efficiency - Power delivered by the motor shaft to the impeller. This is not the same as THP or SFHP. BHP is a function of the load on the motor shaft and will change with Head, GPM and RPM.
- Hydraulic HP (HHP) = BHP * Pumping Efficiency = Head (ft) * GPM / 3960 - Power delivered to the water. Sometimes called water HP (WHP) or pumping HP (PHP).
This was my original question:
Not which motors/pumps they can be used on or a discussion about service factors (which has been greatly discussed on this forum) ...
The answer I received involved was process to look up each motor that Hayward paired with a specific impeller, figuring out the THP of that motor and then inferring that the impeller was a 2.2 THP impeller.
My issue was that websites list the SPX3215C impeller as a 1.5 HP, others as a 2.0 HP and yet others as a 2.4 HP impeller.
The packaging (if it is believable) states its a 1.5 HP impeller. It doesn't define HP in any way or if THP was meant.
In either case, I will let you know what Hayward has to say when they contact me.
- May 3, 2007
- 18,067
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
I understand that but I think the question is technically unanswerable because THP really has no meaning for the impeller, only for motors. The only thing anyone could tell you is which pump model each impeller will work with. From that you can infer a motor THP for each impeller.
All are true depending on the definition of HP. Using just "HP" is ambiguous.
Right, it doesn't, but I think the definition they are using is nameplate HP because this is the same value that is used in the parts lists and in marketing so they wanted to be consistent.
If you have the Performance Curve for the Impeller, you can estimate the power required based on the maximum flow and head loss at the maximum flow.
For example, the maximum flow for a SP3215X20 is about 140 GPM and about 30 feet of head loss.
You can even extend the graph to about 150 GPM and about 20 feet of head loss.
You would have to know the efficiency of the pump at that flow and head loss.
The efficiency is usually highest at the center of the Pump Performance Curve and lowest at the ends of the curve, so the efficiency would probably be pretty low.
In any case, Hayward put a 2.2 HP motor on that impeller, so that should be the correct rating for any replacement motor.
The correct label would be 2.2 hp, not 1.5 HP.
Below is a different pump, but you can see that the efficiency at full flow is about 25%
centrifugal pump power |
pump efficiency | 0.25
fluid density | 1000 kg/m^3 (kilograms per cubic meter)
flow rate | 150 gal/min (gallons per minute)
differential head | 20 feet
gravitational acceleration | 1 g (standard acceleration due to gravity on the surface of the earth)
shaft power | 2.263 kW (kilowatts)
= 3.035 hp (mechanical horsepower)
= 2263 W (watts)
P = (q ρ g h)/η | |
P | shaft power
η | pump efficiency
ρ | fluid density
q | flow rate
h | differential head
g | gravitational acceleration
www.wolframalpha.com
www.pentair.com
For example, the maximum flow for a SP3215X20 is about 140 GPM and about 30 feet of head loss.
You can even extend the graph to about 150 GPM and about 20 feet of head loss.
You would have to know the efficiency of the pump at that flow and head loss.
The efficiency is usually highest at the center of the Pump Performance Curve and lowest at the ends of the curve, so the efficiency would probably be pretty low.
In any case, Hayward put a 2.2 HP motor on that impeller, so that should be the correct rating for any replacement motor.
The correct label would be 2.2 hp, not 1.5 HP.
Below is a different pump, but you can see that the efficiency at full flow is about 25%
centrifugal pump power |
pump efficiency | 0.25
fluid density | 1000 kg/m^3 (kilograms per cubic meter)
flow rate | 150 gal/min (gallons per minute)
differential head | 20 feet
gravitational acceleration | 1 g (standard acceleration due to gravity on the surface of the earth)
shaft power | 2.263 kW (kilowatts)
= 3.035 hp (mechanical horsepower)
= 2263 W (watts)
P = (q ρ g h)/η | |
P | shaft power
η | pump efficiency
ρ | fluid density
q | flow rate
h | differential head
g | gravitational acceleration
pump power at 20 feet of head and 150 gpm - Wolfram|Alpha
Wolfram|Alpha brings expert-level knowledge and capabilities to the broadest possible range of people—spanning all professions and education levels.
www.wolframalpha.com
IntelliFlo3® Variable Speed & Flow Pool Pump
The award-winning, energy-efficient IntelliFlo3 VSF Pool Pump has a quiet design with sensorless flow control, app connectivity, and automation capability.
Last edited:
230 volts at 10.5 amps is 2,415 watts of available power, which seems about right with a bit of margin.
2,415 watts is 3.24 HP.
The pump is labeled as 2.2 total HP, which is 1640 Watts.
This suggests that the motor is about 68% efficient.
If the pump is about 37% efficient at 150 GPM, then that gives a "Wire-to-Water" efficiency of about 25% at 150 GPM.
You can look at the motor efficiency and the pump efficiency and you can look at the combination of motor and pump efficiency.
So, trying to figure out what "Power" a pump, motor or impeller uses is not straightforward at all because there are many different ways to describe power required.
In any case, the engineers are responsible for the calculations, so you just find what motor was used on the original equipment and use the same size or bigger.
Last edited: