On Apr 22, 11:42*am, DD_BobK wrote:
On Apr 22, 8:16*am, "
wrote:





In the Polaris pool cleaner thread the subject of variable speed
pool pumps came up. * Which got me thinking about them
again because a friend who has a pool with a single speed
pump is considering options. Doing a bit of research, here's
*what I have concluded and I wanted to see if anyone has
*addional thoughts.

First, it looks like because of the design of the variable speed
permanent magnet motors, they are inherently more efficient
so you use about 15-20% less energy even at full speed.

Second, the biggest savings in energy come from slowing
the pump down, reducing the flow resistance. *That means
you can run the pump for say 4 times as long, at 1/4 the
flow rate, move the same amount of water, but save 70 to
80% or so in energy.

However, the price of these pumps is very high. *A complete
new pump runs from $900 to $1200 dollars online. *The next
obvious problem is that they typically have only a 1 yr
warranty. * I found an online story where a guy bought
a Pentair Intelliflow one where one of the two small control
boards failed shortly after the warranty ended. *He says
Pentair will not sell the replacement board as a seperate
part or take pumps back for repair. *He would have to buy
a whole new pump. * It looks like Jandy, another major
manufacturer, does sell parts, but the equiv part for their
pump would be $400.

So, this got me to thinking. *It appears to me the biggest
part of the energy savings can be obtained by just going
to a dual speed pump. * And since my friend has a working
pump that is about 5 years old, I'm thinking the most
cost effective solution is to just replace the motor with
a dual speed motor. *We could do that for under $300.

With the variable speed pump, assuming we bought the
lowest cost one, by my calcs, with the energy savings
*it would take almost 4 years
to break even. * With the dual speed motor, it would take
less than 2 years. *The pool is seasonal, used 3.5 months
a year. * And it looks to me like the additional savings in
energy going with the true variable speed pump is only
about $50 more a year over the dual speed. *And then
what happens if the fancy electronics on this motor,
which sits outside all year, fails at say year 3, 5 etc?

The only other advantage of the variable is you can fine
tune it to run at exactly the speed you want, but I don't
see a compelling need for that. *Also, there aren't any
utility rebates available here that would alter the
equation. * So, it seems for this app, the variable speed
makes no sense. * If you had a pool running year round,
higher cost electric, rebates, etc, then the results
might be different.

So, swap out the motor for the dual speed for $300? *Any other
thoughts, issues I missed?

T4-

Looks to me like you covered all the issues..... *dual speed is right
choice.
Fancy electronics (unless cheap to replace) will eat up any energy
cost savings when the board fails. *

cheers
Bob- Hide quoted text -

- Show quoted text -

I don't have a pool, but the OP seems to have his ducks right in line.