230 vs. 115v power for Pentair SUPERFLO VS

[mvoltin]

I have option of connecting the pump to either 230 or 115 but always assumed pumps ran better with 230 and this was my plan. I just noticed the efficiency with 115 connection is higher (WEF 7.3 vs. 6.6). Is there another compelling reason to use 230v connection? horsepower and other stats are the same - so confused.

 

[JamesW]

In my opinion, the WEF is mostly a useless number.

At 120 volts, the pump won't perform to the full potential as shown in the pump performance curve.

At 120 volts, the drive reduces the rpm as needed to keep the current below the limit.

If you have a choice between 120 or 240, I would always go with 240.

 

[drsipe]

I'm not sure about the efficiency of this pump comparing 115 to 230V, so that may make a difference in what I am about to tell you. Basic electricity, the big difference is that using actually 220, you can use smaller wire which is cheaper to run, and since the amperage is lower, there is less resistance in the wire. The motor should take about the same wattage to operate 110 or 220, but with higher voltage, amperage is much lower (voltage x amperage = watts). Amperage is a measurement of flow, higher flow (amperage) creates more resistance (heat) and requires larger wire. In my experience it's always better to use 220 on any large current draws, such as pumps and heaters.

 

[mvoltin]

I'm not sure about the efficiency of this pump comparing 115 to 230V, so that may make a difference in what I am about to tell you. Basic electricity, the big difference is that using actually 220, you can use smaller wire which is cheaper to run, and since the amperage is lower, there is less resistance in the wire. The motor should take about the same wattage to operate 110 or 220, but with higher voltage, amperage is much lower (voltage x amperage = watts). Amperage is a measurement of flow, higher flow (amperage) creates more resistance (heat) and requires larger wire. In my experience it's always better to use 220 on any large current draws, such as pumps and heaters.

I agree and understand what you said. the problem (or my situation) is that I already have #6 wire that should support max amperage on either 115 or 230 (I initially planned on heat pump - no considering gas heater - hence, extra bandwidth in wires). I was just surprised that it runs almost 10% more efficiently with 115v. Like you, I always heard that, if there is an option, always use higher voltage. In addition to wire sizing needs, I always assumed the motor ran at a higher efficiency when using 230...

 

[JamesW]

I don't think that the efficiency is better at 115 volts. The WEF number is useless and confusing. The pump won't produce the full gpm possible, so the WEF numbers are not comparable.

See the pump performance curve where the 115 volt curve deviates from 240 volt curve.

Comparing the WEF at two different gpm flow rates is not correct.

I would definitely recommend 240 volts.

 

[Jimrahbe]

M,

If JamesW told me that the Moon was made of Swiss Cheese, I'd believe him..

Just saying...

Thanks,

Jim R.

 

[JamesW]

Weighted Energy Factor (WEF) is a standardized measurement of how much energy is required to move the water in terms of gallons per kWh of energy use.

A pump with a WEF of 7.847 means the pump is rated as being able to pump 7,847 gallons of water with one kWh of energy.

The problem with the WEF is that the gpm is not part of the equation.

You can move 7,847 gallons a lot more efficiently at 20 gpm than 40 gpm or 80 gpm through the same system.

So, unless you know that both pump's WEF numbers were measured at the same gpm, the WEF is not going to tell you the real information.

In my opinion, the WEF should be given at specific flow rates and on the exact same system curve.

In my opinion, giving the amount of water (gallons) moved for a specific amount of energy is a bogus term without specifying the flow rate and head loss.

In the case of the Superflo vs, it doesn't make sense that the pump would have any efficiency difference between a 115 volt supply and a 230 volt supply when moving the same gpm through the same system curve and the same head loss.

The pump affinity law shows that the power required to move water increases exponentially as the gpm increases.

For example, if the gpm is doubled, the power required is 6 to 8 times as much.

To move a set number of gallons, doing it twice as fast will take half the time. So, the energy used will still be 3 to 4 times as much.

For example, if you run at full speed and it's 2,000 watts for 8 hours, you will use 16 kilowatt hours.

If you run at half speed and it's 333 watts at 16 hours, it takes 5.333 kilowatt hours.

So, running at full speed takes 3 times as much energy to move the same number of gallons.

 

[JamesW]

120V vs 240V - Superflo VS Pump - More efficient at 120V?

Looking at the Superflo VS pump specs: 115-volt: WEF 7.3 THP 2.2 230-volt: WEF 6.6 THP 2.2 Does this mean it is more efficient at 120V than 240V? I know I'll get a higher flow rate at high speeds at 240V, so I may go that route anyways. Any reason to go for one voltage over the other...

www.troublefreepool.com

 

[mvoltin]

Weighted Energy Factor (WEF) is a standardized measurement of how much energy is required to move the water in terms of gallons per kWh of energy use.

A pump with a WEF of 7.847 means the pump is rated as being able to pump 7,847 gallons of water with one kWh of energy.

The problem with the WEF is that the gpm is not part of the equation.

You can move 7,847 gallons a lot more efficiently at 20 gpm than 40 gpm or 80 gpm through the same system.

So, unless you know that both pump's WEF numbers were measured at the same gpm, the WEF is not going to tell you the real information.

In my opinion, the WEF should be given at specific flow rates and on the exact same system curve.

In my opinion, giving the amount of water (gallons) moved for a specific amount of energy is a bogus term without specifying the flow rate and head loss.

In the case of the Superflo vs, it doesn't make sense that the pump would have any efficiency difference between a 115 volt supply and a 230 volt supply when moving the same gpm through the same system curve and the same head loss.

The pump affinity law shows that the power required to move water increases exponentially as the gpm increases.

For example, if the gpm is doubled, the power required is 6 to 8 times as much.

To move a set number of gallons, doing it twice as fast will take half the time. So, the energy used will still be 3 to 4 times as much.

For example, if you run at full speed and it's 2,000 watts for 8 hours, you will use 16 kilowatt hours.

If you run at half speed and it's 333 watts at 16 hours, it takes 5.333 kilowatt hours.

So, running at full speed takes 3 times as much energy to move the same number of gallons.

Thank you, James. This makes perfect sense.

 

[JamesW]

In my opinion, the WEF numbers are ridiculous and useless.

Trying to give a single number for the "efficiency" of a pool pump is stupid and worthless.

No one is going to use the number other than for marketing that exploits people's ignorance, like what happened with horsepower and service factor.

The only thing that the WEF does is incentivize the manufacturers to try to game the system to get better WEF numbers even when the changes are counterproductive.

99.9% of people don't know how to select the best pump anyway. Adding another metric will do nothing to make the situation better, especially because the metric is completely meaningless.

The WEF will make zero difference in anyone's ability to choose the best pump for their application.

In my opinion, the power usage in watts should given for specific operating points where the gpm and TDH are given.

Every manufacturer can produce a chart where the power, gpm and TDH are given for multiple points.

In addition, the manufacturer should be able to provide a calculator that can accept inputs such as rpm, TDH, gpm and power and provide the missing variables.

For example, if you input the tdh and gpm, the calculator will return the rpm and watts.

The calculator should even be able to tell you the best pump for your application based on your system requirements.

That way, you can compare one pump against another in a fair and accurate way.

Until the numbers are transparent about exactly what they are measuring, they should be ignored, in my opinion.

 

[JamesW]

The important thing about efficiency is how much power a pump will use on your application, not on some theoretical system that is unlikely to match yours.

For every system, there are one or more flow rates that you will want or need to accomplish what you’re trying to do.

At each flow rate on your system, there will be a corresponding TDH (Total Dynamic Head), which is the amount of resistance produced by moving the water through the system.

What matters is how much power a pump will use for your unique application.

This would be relatively easy for manufacturers to measure with their current test equipment. They could produce charts and calculators that will output the power at any input THD and gpm. In fact, this is what Pentair has already done with the Intelliflo to allow it to calculate the flow on its variable flow models. The intelliflo calculates the TDH and the flow (GPM) from the RPM and the power usage.

Once you know the amount of power needed at each flow rate, you would multiply the power by the time needed for each flow rate and that will give you the amount of energy needed in kilowatt hours, which is what you pay for.

The people pushing WEF say it’s analogous to MPG for a car, but it’s a completely different situation.

The power usage of a pump changes exponentially by a cube factor. So, going from 30 gpm to 60 gpm uses 2³ or 8 times as much power.

For a car, the amount of gas required does not increase by 8 times when going from 30 to 60 miles an hour. If that were true, the mileage would go from 40 mpg to 5 mpg when going from 30 to 60 miles per hour. In that case, what mpg rating should the car get? 5? 40? Somewhere in between? Depends a lot on how fast you're going to drive. Without knowing how fast you're going to drive, it's pointless to say what the mpg will be.

Interesting note. Pumps with three-phase motors are exempt from the WEF requirements. Variable speed pumps have three-phase motors. So, one could argue that they are exempt from the requirements.