Hundreds of pool and spa professionals packed
into conference rooms at the AQUA Show and the
International Pool & Spa Expo this fall to talk
about the problem. It's been the focus of several trade magazine articles, and since 2001 the state of California has invested over a million dollars to educate builders and retailers on the issue.
What's all the hubbub about oversized pumps? They've
been turning over pools without much comment or incident for more than 50 years. And if they've been a bit
huskier than necessary, what's wrong with a little extra
horsepower in the circulation system. Most people, indeed
most customers, see that as a positive.
Unfortunately, it's not. While "a little extra horsepower"
may be useful under the hood of your car, in a pool circulation system, it's very bad news.
The reason is found in the physical equations that govern fluid flow through a pipe.
Most of the time, our natural laws offer no bargains.
That is to say, most equations of physics are linear. If a
new model of car is a pound lighter, for instance, its force
in a crash at the same speed is a pound less.
But when it comes to pool water in a pipe, friction losses
go up exponentially with increased .ow. And therefore, so
does waste, in terms of kilowatt-hours, and the pool owner
is paying for it.
If the industry can be shown how to circulate pool water
using smaller pumps, the implications for its customers are
huge — and getting larger with each utility rate increase.
Because the pump is such an energy hog, a pool owner's
savings in utility bills can be eye-popping. Scott Clay, program manager for Pacific Gas & Electric in San Francisco,
estimates the savings for a typical California pool owner
(where rates are higher than most states) switching to an
energy-efficient motor and pump using lower head to be
$600 per year.
In 10 years, that's $6,000 in utility bills alone — to say
nothing of the enormous savings in the cost of premature
component failures. Tack that on to the bill, too. High .ow
rates can damage filters, heaters, plumbing components
and pumps. For example, with too
much water coming through under
high pressure, sand filters become
channeled, and DE filter grids are
prone to collapse.
It all adds up to high pool-operating
costs, a drag on future sales and
needless depletion of resources. In
the state of California alone, according to Clay, it takes three fully functional power plants to provide the
electricity that is wasted by pool
pumps. If every pool owner in the
state would switch to a less-costly,
more-efficient pump, the state could
actually shut these power plants down
— or use them to meet growing demand instead of building new ones. Scale these figures across the United States and they show that the effort to promote sensible pool-pump
sizing and lower line speeds could
have a real impact on the overall energy consumption (and energy dependence) of the entire nation.
The problem, in a nutshell, is that too
many swimming pool pumps are
oversized. That means that .ow rates
are frequently too high, and the faster
you try to put that water through the
system, says Steve Gutai, Waterpik
Technologies' product manager for
pumps, filters, valves and water features, the more resistance is created.
At this point, the pump is really
wasting electricity. To quantify that,
Clay's group at PG&E has done some
calculations. "The staggering part, as
far as the cost to the California customer is concerned, is that by using
that amount of energy just for the
pool, their overall usage goes up into
the higher tiers of our rate structure. In California, the more you use, the
higher rate you pay.
"So based on these penalties, a
Central Valley pool owner may be
paying an extra $50 to $80 per month
to operate their pool pump. By
switching to an efficient motor and
two-speed pump, they can save that."
For the utility that Clay represents,
and ultimately, the general public it
serves, the timing of usage is just as
important as the amount. "Pool
pumps run at the peak hours of energy usage," he says, "from noon to six. That's when everybody in California
uses their air conditioning and so on. So reducing the load of these pool
pumps means a whole lot in terms of
reducing peak power."
In addition to wasting scandalous
amounts of energy, oversized pumps
result in higher noise levels and premature equipment failure, notes Skip
Phillips, owner, Questar Pools and
Spas, Escondido, Calif.
"Let me give you an analogy," he
says. "It's like sticking a 500-horsepower engine in a Mini Cooper. And
we're not going to change anything,
we're not going to redesign the transmission, we're just going to let it selfdestruct. Everything downstream gets
That's true, agrees Gutai. "If your
pump is oversized, you could potentially cause damage to the filter components and your filtration system
will not be as efficient.
"If you have a sand filter it will
cause channeling as the water drives
itself through the sand bed too quickly, resulting in poor filtration. If you
have a cartridge filter or a D.E. filter,
it will contribute to the collapse of the
cartridge or the grid."
If oversized pumps are so expensive
to run and are so hard on the circulation system, why are so many of them
Human nature. Pervasive myth. If
the pump is the engine of the circulation system, then the biggest,
strongest engine is best, isn't it.
Of course the answer is no, but to
many people, both outside and inside
the pool industry, this myth is just
common sense, applicable to machinery in general; planes, trains, blow
dryers — you name it.
And while few contractors will say
so on the record, it is a fact that many
builders try to win sales with bids that
include higher-horsepower pumps
than are necessary. They do this because it frequently works; the horsepower myth is accepted by most customers as a simple and obvious truth. To them, the contractor that is offering a higher-horsepower pump is offering a better pool.
Particularly in the highly competitive above-ground market, where buyers often compare advertisements
from two or more retailers, the spec
with the 1-horsepower pump looks
better than the one with the - horsepower pump.
"People are convinced that their
system is being degraded if they fail
to have these high-horsepower systems," says Phillips.
At this point in the sales process,
notes Rob Stiles, product manager,
pumps, Pentair Water Pool & Spa,
Sanford, N.C., efficiency can be an
awkward topic, because it forces the
salesperson to focus on the ongoing
energy costs associated with pool
ownership. "You've got to explain to
someone that it's going to cost them
money even after the pool's paid for,"
he says. "And that's not something
that a lot of people in the pool business want to talk about."
Slow It Down
The key to efficiency, whether you sell
on it or not, is lowering the flow rate. Reduce flow rate, says Clay, and you
dramatically cut the electric bill. "There's a law of physics at work here
called the affinity law," he notes. "And what it states is that, in an ideal
system, when flow is reduced by onehalf, the energy draw drops by oneeighth. What we find in a real system
is that it actually drops by one-fifth."
The needs of the pool, of course,
must not be sacrificed in the process. One good way to meet equipment
needs and still save the maximum
amount of energy is by installing a
A two-speed pump has a high
speed that runs at 3,450 rpm and a
low speed that runs at 1,725 rpm. The high-speed mode is useful in highbather-load situations or to address other system needs. The low speed isused for normal filtration; when you drop the motor speed to half, efficiency goes through the roof.
"The typical 1 1/2 or 2-horsepower
pump runs at about 9- to 14 amps,"
says Clay. "So when you drop that
same size pump down to half speed,
you're drawing between 2 and 4
amps. That's a huge difference, even
after you factor in the fact that at half
the .ow, you have to keep it on twice
as long. Taking that into consideration you end up using between one-fourth and one-half the energy."
At the same time, pump manufacturers are introducing new products
to help solve the problem and save
consumers money. For instance, Pentair recently introduced a pump with
a variable-speed drive, according to
"It uses a processor and a computer
to size itself to the system," he says. "You input pool size (say 20,000 gallons) turnover time, and when to run
(10 hours, between 8 a.m. and 6
p.m.), and the pump will calculate the
most efficient point to run."
While new products are arriving on
the market and awareness is growing, change takes time. Clay has been
working to educate Californians on
the need and the means for change
for the last three years. His group is
part of a strong push by electrical
utilities in the state for pool pump
downsizing with education programs
and generous rebates to homeowners
— as much as $300 for downsizing
to a two-speed pump and energy-efficient motor.
And in his three-year effort to fight
excess resistance in pool plumbing,
Clay has encountered some resistance of his own. "When we went to
the pool service association meetings," he says, "and came to the subject of [switching to] two-speed
pumps, the congregation would get
kind of unruly. Many of them felt
they would not work on pools.
"We heard things like: 'You don't
get enough flow in the pool to get
good circulation. There's not enough
flow to make the weir skimmer
work. Not enough pressure to make
the pressure cleaner move around
the pool or to fill the solar heating
Good pool circulation is not an
issue with lower line speeds, Clay
says. In fact, it is improved. He
points out, for instance, that a pool
that is turned over in 16 hours at low flow and then sits for 8 hours will provide cleaner, better-mixed water than one that is circulated 8 hours at high flow and then sits for 16 hours.
And where necessary, he says, the
pressure needs of the solar panels
and the automatic cleaner can be addressed by starting a two-speed
pump on high speed for an hour or
two, and then once the solar panels
are full or the automatic cleaner has
performed its job, reducing to low
Phillips's experience has been similar to Clay's. After teaching seminars
on pool circulation, Phillips has come
to believe that most industry personnel are unaware of the problem of
oversized pumps — and are contributing to it. In class, he displays
what he calls a "typical" pool circulation system — which includes an
oversized pump. "And everybody's in
there nodding, saying, 'Yeah, I do
that.' And then I tell them there's absolutely no justifiable reason to do
Clay believes the message is getting
through in California, with the combined effect of education and customer rebates. "We're starting to win
folks over," he says, "but it's been a
California: Land Of The
Necessity is the mother of attention,
to tweak an old adage, and in some
ways the emergence of oversized
pumps as an issue is a result of the
California energy crisis. Says Stiles,
"I think what gave the big kick to the
industry to start moving was the
state of California and everything
that's happened out there in terms
With energy prices still astronomically high by most standards, the
pressure to conserve has produced
tangible gains, he notes. "Now they've
got guys running pools out there on a
third of a horsepower, when in the
past you might see a two- or three-horse pump on there."
There's a long way to go, however. It is a classic issue of industry maturity. Growing pains. Thirty years ago,
notes Gutai, when pools were simple
and energy plentiful, having a higherhorsepower pump hardly mattered. It's different now.
"Projects today can be much more
complex," he says. "Now you have
multi-level pools with vanishing
edges, with gravity feed systems, with
extensive water features and spas. And swimming pool builders understand that to execute a job like that,
where they can make a lot more
money, they need to understand fundamental concepts of hydraulics."
In assessing progress, Gutai is optimistic: "Across the nation, I think
pool builders are getting more and
more attuned to this problem. I think
they're learning the proper way to
According to the Residential Pool
Standard established by NSPI (soon to
be administered by the International
Aquatic Foundation), in no case
should water velocity be greater than
10 feet per second at the pump outlet
or 8 feet per second at the pump inlet
using PVC pipe. For copper, 8 feet per
second is the maximum.
Scott Webb has been with AQUA magazine in one capacity or another since April 2001; he now serves as executive editor. Scott has a degree from University of Cincinnati in Aerospace Engineering and lives in Madison, Wisc.