Question on Energy Efficient Pump Driving Caretaker In-Ground Cleaning System

[mas985]

I agree with Doc. An in-floor system is the antithesis of energy efficiency. Energy use of any pump is primarly driven by flow rate and pressure (i.e. hydraulic power). So if you want the same performance out of the your in-floor system, the flow rate will need to be nearly the same to achieve the same pressure at each popup head and the hydraulic power will need to be the same no matter what pump is used.

As for efficiency of the pump, it can be broken down into two parts, the wet end pump efficiency and the motor efficiency.

Most variable speed pumps use the same wet end as the largest single speed in a pump line. For example, the Intelliflo uses the same wet end as the Whisperflo WFE12 and the EcoStar is the same as the Tristar 3220EE wet ends. So the variable speed wet end performance should be no different than their single speed counter parts that use the same impeller. But pump efficiency is also dependent on the impeller size, diffusor clearances and other factors. So in general, smaller pumps tend to have lower pump power efficiency but higher gallons/watt-hr efficiency. While the flow rate decreases for smaller pumps, the power use decreases much faster.

Motor efficiency is a different story. A VS pump, primarily those that use permant magnet motors such as the Intelliflo and EcoStar, have very effiicient motors and so their efficiency tends to be a little better than a single speed pump at the same flow rate (~5%-20%). But the increase in motor efficiency can be offset by a less efficient wet end design.

For example comparing your pump to the Intelliflo at the same flow rate using the CEC plumbing Curve-A:

RS2002: 67 GPM @ 2040 watts - 2 gallons/watt-hr

Intelliflo: 67 GPM @ 2067 watts (3300 RPM) - 2 gallons/watt-hr

EcoStar: 67 GPM @ 1771 watts (3300 RPM) - 2.3 gallons/watt-hr

The EcoStar actually does better than the Intelliflo which is probably due to a better wet end & VFD design.

How much you save and when the pump pays for itself will depend on how much you run the pump. Technically, you may only need 3 hours per day at that flow rate to turnover the pool once per day but most people will run the pump longer to have circulation during the day and run the cleaner. Also, total savings will depend on how much time that you run the pump at lower speeds vs higher speeds.