Noise levels PMSM vs TEFC vs ODP

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phillip123

Member
Jan 24, 2025
7
Louisiana
I have a Pentair Vsf pump with a PMSM motor that drives a water feature. It always runs at 3400rpm, and I have found it to be relatively quiet. Unfortunately, the motor died, and I have been advised to replace it with a single-speed Pentair TEFC motor or a Century ODP motor.

In reading the forums, I see that one of the TFP Experts has frequently observed that the external fan on TEFC motors is annoyingly loud. My water feature used to be driven by a Pentair Challenger ODP pump that I also found to be annoyingly loud.

Should I expect a replacement single-speed TEFC motor (at a fixed 3450rpm) to be a lot louder and more annoying than my current PMSM motor (which I have found to be okay noise-wise running at 3400rpm)?
Or, put another way, is the PMSM motor significantly quieter than the TEFC motor? Than an ODP motor?
 
The variable speed motor is TEFC.

At 3,450 RPM, all motors are loud.

My observation is that at 3,450 RPM, the TEFC motor is usually louder than a ODP motor where the fan is inside.
 
phillip123 said:
I have a Pentair Vsf pump with a PMSM motor that drives a water feature. It always runs at 3400rpm, and I have found it to be relatively quiet. Unfortunately, the motor died, and I have been advised to replace it with a single-speed Pentair TEFC motor or a Century ODP motor.

In reading the forums, I see that one of the TFP Experts has frequently observed that the external fan on TEFC motors is annoyingly loud. My water feature used to be driven by a Pentair Challenger ODP pump that I also found to be annoyingly loud.

Should I expect a replacement single-speed TEFC motor (at a fixed 3450rpm) to be a lot louder and more annoying than my current PMSM motor (which I have found to be okay noise-wise running at 3400rpm)?
Or, put another way, is the PMSM motor significantly quieter than the TEFC motor? Than an ODP motor?
Click to expand...
Pentair has TEFC, single-speed motors. 354815S is 2hp. 324821S is 1hp.
 
You can do a Waterfall pump, which runs at 1,725 RPM and that should be quieter.

www.pentair.com

WaterFall Specialty Pumps

The Pentair Waterfall Specialty Pool Water Features Pump has a closed impeller, low-head pump ideal for water features such as fountains, waterfalls and other special pool features.
www.pentair.com www.pentair.com

A Large Variable speed pump can potentially be run at lower speed to make it quieter.

The lower the RPM, the quieter the pump.

How much flow do you need?

What size is the Suction Plumbing line and how long is it?

What is the current pump?
 
Noise is also subjective on the person and the pump location. My pump is located right outside my kitchen window and the old single-speed motor seemed quieter when I was next to it than my newer variable-speed motor at full-speed, but the old motor had a lower sound which transmitted into the house. When I am indoors, I can't hear the VS motor at full-speed at all but I could easily hear the low-pitched hum of the single-speed motor when I was indoors.
 
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JamesW said:
Here, you can see the internal fan.
View attachment 625671

Century 56Y Full Rate Single Speed Series B2846, B2847, B2848, B2858, B2849, B849, B2748 Parts - INYOPools.com

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Below is the IntelliFlo TEFC with the back fan.
Click to expand...
Again, very helpful. Thank you.
 

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JamesW said:
You can do a Waterfall pump, which runs at 1,725 RPM and that should be quieter.

www.pentair.com

WaterFall Specialty Pumps

The Pentair Waterfall Specialty Pool Water Features Pump has a closed impeller, low-head pump ideal for water features such as fountains, waterfalls and other special pool features.
www.pentair.com www.pentair.com

A Large Variable speed pump can potentially be run at lower speed to make it quieter.

The lower the RPM, the quieter the pump.

How much flow do you need?

What size is the Suction Plumbing line and how long is it?

What is the current pump?
Click to expand...
The water feature in question is a 21ft. long negative edge.

I had thought about a waterfall pump, and started looking into it, but when I consulted the TFP Pump Database, it lists the GPMc for my current pump (Pentair IntellifloXf Vsf, #022056) as 100.94gpm, and the GPMc for the old, previous pump (Challenger CHII-N1-2-1/2A) as 93gpm. On the other hand, I was very surprised to see the GPMc for the AF-180 waterfall pump listed as only 55.47gpm. (Am I somehow reading this wrong?) Anyway, since the Challenger underdrove the 21ft. negative edge, I decided, based on this 55gpm GPMc figure in the pump database, that the AF-180 (or AFP-180) waterfall would definitely underdrive the negative edge. Does this make sense, or am I missing something?

I apologize, but unfortunately, I don't know how much flow I need, just empirical evidence. The Challenger CHII 2.5HP high pressure pump (Performance Curve K in the Pentair pump literature) was insufficient to drive the entire length of the 21ft. negative edge. The current IntellifloXf Vsf pump (#022056) running at 3400rpm is fairly good at driving most of the 21ft. length, but not terrific.

The plumbing lines are 2.5". The pump is on its own concrete pad, and the plumbing lines disappear underground immediately off the pad. I will measure the distance from the pad to the pool today and report back to give you an idea of suction line length.
 
InyoRich said:
Noise is also subjective on the person and the pump location. My pump is located right outside my kitchen window and the old single-speed motor seemed quieter when I was next to it than my newer variable-speed motor at full-speed, but the old motor had a lower sound which transmitted into the house. When I am indoors, I can't hear the VS motor at full-speed at all but I could easily hear the low-pitched hum of the single-speed motor when I was indoors.
Click to expand...
That's interesting. I absolutely agree about pump location. Most of the pool equipment is on the side of the house, away from the pool, and very quiet. The water feature pump, on the other hand, is located separately and very close to the pool. When it was a single-speed ODP pump, it was annoyingly loud. The IntellifloXf Vsf has been a vast improvement.

I am, or at least was, worried that the single-speed TEFC motor, with its external fan, will be a step backwards noise-wise. However, as JamesW explained, the variable-speed PMSM motor is still a TEFC motor with an external fan. So, possibly the two motors are comparable, noise-wise?
 
phillip123 said:
The water feature in question is a 21ft. long negative edge.
Click to expand...
For 2.5" lines, the flow for suction should be limited to about 90 gpm, which is 4.28 GPM per foot or just under 1/4" lift over the edge.
However, you can generally get up to about 17 feet of head loss before the pump begins to have issues.

Assuming a 100 foot long line, that allows up to about 167 GPM, which is 7.95 GPM/ft, which will give just under 3/8" lift.

If the return is also 100 feet at 2.5", then the total head loss is about 35 feet of head loss.

If we use a 5 hp WhisperFlo xf 5 hp pump, you can get this at about 2,700 RPM.

For an AFP-150, you might get about 110 GPM, which is 5.23 gpm/ft, which is just over 1/4" lift.

Infinity Edge Flow vs. Lift
1737817901130.png
phillip123 said:
The plumbing lines are 2.5".
Click to expand...

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www.engineeringtoolbox.com

Hazen-Williams Water Flow Formula: Head Loss, Data, Charts & Calculator

Friction head loss (<i>ft<sub>H2O</sub> per 100 ft pipe</i>) in water pipes can be estimated with the empirical Hazen-Williams equation.
www.engineeringtoolbox.com www.engineeringtoolbox.com

Equipment Pad Best Practices - Further Reading

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New Construction Started - Willis, TX (north of Houston)

After a year of due diligence and research we finally broke ground. I'm a bit in arrears but here's the progress over the first 4 days: 6/2 - Dig Day 1 6/3 - Dig Day 2 6/4 - Steel (#5 for footing/#3 for footing "wrap-arounds), #4 everywhere else. 8" thick gunite for floor, 6" for footing...
www.troublefreepool.com www.troublefreepool.com

 
Intelliflo VSF 140 gpm at 3110.

1737820665534.png

Intelliflo XF 170 gpm at 35 feet at 3,110 rpm.
1737820107249.png

www.pentair.com

IntelliFloXF VSF Pump

Pentair IntelliFloXF VSF Pump - This innovative, variable speed & variable flow pool pump offers precision and savings for large and feature-rich pools.
www.pentair.com www.pentair.com

www.pentair.com

WhisperFloXF® VS 5HP Variable Speed Pump

The WhisperFloXF VS 5HP Commercial Pump is the first five-horsepower variable-speed pool pump that runs on single-phase or three-phase power.
www.pentair.com www.pentair.com

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IntelliFlo® VSF Variable Speed and Flow Pool Pump

The IntelliFlo VSF pump is the first of its kind to respond to changes in your pool’s environment in order to maintain a preprogrammed flow rate. There’s no more guesswork—just set the desired flow rate and the pump will adjust as needed. It’s like cruise control for your pump. And, the...
www.pentair.com www.pentair.com
 
Note: Assumes 2.5" lines with an Equivalent Length of 100 feet and the pump is at the same elevation as the pool.

You have to subtract the height of the pump inlet to the pool water surface in the trough while operating.

If the Pump inlet is 5 feet above the water in the trough, then you only have about 12 feet of suction to work with.

That limits the flow to about 140 gpm, 6.67 gpm/ft, about 5/16" lift.


1737821548559.png
 
phillip123 said:
Yes, that's one of the motors I'm being advised to use. (That, or a Century ODP.) These are the WhisperfloXf motors, correct? I've been advised to replace the IntellifloXf Vsf variable speed motor with one of these single speed TEFC units.
Click to expand...
Yes. If you aren't going to use the speed control of a VSP, why spend the money if you have good results now.
 
JamesW said:
If the Pump inlet is 5 feet above the water in the trough, then you only have about 12 feet of suction to work with.
Click to expand...
Below, the last column is the amount of dynamic head loss that the suction line can have at that flow before the pump begins to have suction problems.

Total head = Total Suction head loss plus total return head loss.

Total Suction head loss = Static head loss plus dynamic head loss.

Since the pool is higher than the trough, the system has a net static head loss equal to the height difference from the pool water level to the trough water level while the pump is on.

This is usually about 3 to 5 feet.

Static Suction Head Loss is typically about 2 feet more than net static head loss because the pump inlet is usually about 2 feet higher than the pool water level.

So, you can probably hit about 155 gpm before getting into cavitation range.

Flow..........NPSHr........Total..........-5 feet.

100...............9...................25.............20
120............10....................24.............19
140.............12...................22.............17
150.............13...................21.............16
155.............14...................20.............15
160.............15...................19.............14
180.............17...................17.............12


1737823050807.png
1737822147401.png
phillip123 said:
I've been advised to replace the IntellifloXf Vsf variable speed motor with one of these single speed TEFC units.
Click to expand...

phillip123 said:
my current pump (Pentair IntellifloXf Vsf, #022056)
Click to expand...

phillip123 said:
The current IntellifloXf Vsf pump (#022056) running at 3400rpm is fairly good at driving most of the 21ft. length, but not terrific.
Click to expand...
The pump might be underperforming due to the undersized suction line.

The line should be about 4".

Once you exceed about 155 GPM, the pump is probably underperforming.

You can put a vacuum gauge on the suction near the pump to see where the head loss is.

The gauge measures the total suction head loss, which includes the static and dynamic.

Once the NPSHr drops below the requirements the pump can begin to underperform.

NPSHr = 34 - head loss in feet.

For example, if the vacuum is 15" Hg at 180 gpm, the head loss is 17 feet (5 static plus 12 dynamic).

The NPSHr = 34 - 17 = 17.

So, at 180 gpm, the pump is getting 17 feet of NPSH, which is what is required.

If the vacuum is 17" Hg, the head loss is 19.3 feet.

The NPSHr = 34 - 19.3 = 14.7, which is ok up to about 160 gpm.


1737823390810.png
1737823774780.png


Convert in Hg to foot of head - Conversion of Measurement Units

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The quietest pump might be a Whisperflo XF 5 hp Commercial.

You can probably hit 150 gpm at about 2,500 RPM.

You can use a vacuum gauge to slowly increase the speed while watching the vacuum to know when you hit the vacuum limit.

This will give you maximum performance at the quietest speed.

Most likely, the pump will begin to cavitate somewhere between about 2,600 RPM and 3,000 RPM.

1737824562113.png
 
phillip123 said:
Should I expect a replacement single-speed TEFC motor (at a fixed 3450rpm) to be a lot louder and more annoying than my current PMSM motor (which I have found to be okay noise-wise running at 3400rpm)?
Click to expand...
Either one will be loud, but in slightly different ways.

What model numbers are you being quoted for replacement.

The total HP needs to be at least 3.45 hp and maybe up to 3.95 hp.

A 3 hp with a Service Factor of 1.3 should work.

The motor total HP is about 3.95 hp.

Pentair IntelliFlo 3.2 Kw Variable Speed Almond Motor - 350305S

1737836645371.png

The WFE-12 has a 3.45 hp motor.

355033S

Pentair Replacement Pool Pump Motor, 3HP, 230 Volt, Single Speed, 56Y Frame - 355033S Standard E 230V - INYOPools.com

Pentair Replacement Pool Pump Motor, 3HP, 230 Volt, Single Speed, 56Y Frame - 355033S Standard E 230V
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Pentair Replacement Pool Pump Motor, 3HP, 230 Volt, Single Speed, 56Y Frame - 355033S Standard E 230V

Century (A.O. Smith) 3.0 HP Full Rate EE Motor, Square Flange 56Y Frame, Single Speed - Model B2844 - INYOPools.com

Century 3.0 HP Square Flange 56Y Full Rate EE Motor - B2844
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HP = 3, RPM = 3600, Voltage = 208-230, Amps = 15.0-13.6, Service Factor = 1.15, Frame = 56Y, Shaft = Threaded.

1737826105178.png
www.pentair.com

IntelliFloXF VSF Pump

Pentair IntelliFloXF VSF Pump - This innovative, variable speed & variable flow pool pump offers precision and savings for large and feature-rich pools.
www.pentair.com www.pentair.com


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1737828237422.png


Motor, Pentair WF/WFXF, 3.0hp, 208-230v, 1-Spd, 56Y, SQFL, TEFC - 354817S - INYOPools.com

Motor, Pentair WF/WFXF, 3.0hp, 208-230v, 1-Spd, 56Y, SQFL, TEFC - 354817S
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Motor, Pentair WF/WFXF, 3.0hp, 208-230v, 1-Spd, 56Y, SQFL, TEFC - 354817S. $749.99

Pentair Motor 3.0 HP, Square Flange, High Efficiency 208-230v - 355016S - INYOPools.com

3hp High Eff 208-230V - Pool & Spa Parts
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Volts:208-230 V
Total HP:3.45 HP
Single Speed Pump:Single
Phase:1
Flange:Square
Amps:15.0A-13.36A amp
Shaft:Threaded

 
Last edited:

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