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.