Installing a lot of IntelliFlo's keeps me pretty much in tune in dealing with all of these estomates. The first thing one needs to be mindful of is that we are always dealing estimates so that is exactly what they are. Anyone who says you will save this much is giving more sales pitch than sales advice. Voltage fluctuations, system head changes and equipment degrading all figure into the equation.
I can tell you this based on those rough numbers that should be used for shopping comparison. Keep in mind, the degree to which you invest is the degree at which you will save. If you took a hypothetical pool motor that turned 60gpm for 5 hours per day and installed a two-speed pump in it's place and only ran it on low speed for 10 hours, your savings would be about 25%. Full flow at high speed equals half of the flow at low speed. To filter the same amount of water will take twice as long but the power consumption is 1/8 of what it was at high speed. This equates to the 25% savings number.
Savings lower slightly as you run the higher speed for sweeps, jets, etc. To bump up a level of savings you would go into something like a 4x160. Most of these will run as two speeds but the high end speed is usually lower than a typical single speed pump AND the motor is much more efficient. Savings typically run about 40% on this type of pump if properly programmed.
Moving into a true variable speed pump such as an IntelliFlo 3.2 costs the most, but it's payback is greatest. The main reason being that the speed is constantly seeking the most efficient and that is what a 4x160 or lesser pump can't do. When using a clamp on watt meter on the old motor and then reading the on board watt meter on an IntelliFlo, we find most owners are consuming about 12-15 thousand, yes thousand watts LESS per day. That is the number you need to consider.
It's the equivilant of leaving 15 lights on in your house every day when you leave for work. That is exactly what we do everyday with a single speed pump. That might not seem like a lot when you're paying low rates of .08/kw as I have seen some post. In California, where we cannot install a single speed pump any longer, that rate is upwards of .32-.35/kw and we use a tier system of rates. So, savings of $5-6/day are easily obtained around here and in a month that amounts to over $150 savings when operating at peak time. Suddenly the $1500 cost to install makes sense. It's not like paying more for gas in your car. There you pay more and get hte same mileage. With pumps like this, you are paying more up front but sending less to the utility ach month.
The final kicker that most don't realize around here is the tier reduction. If you can knock out 350-450kw off of your bill each month, you are usually keeping yourself out of that upper tier and the higher rate that goes with it. This lowers your cost for all other usage in the home as a side benefit as they operate at a lower rate per kw.
It really comes down to money that you have to purchase today. If you spend it, there is a return. As soon as you spend it, that money goes to work for you the next day. a pretty good deal in a day when everything else drains us.