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Can you really
reduce your
electricity bill?
By JOHN CAMERON*
With recent large increases to commercial and domestic electricity
tariffs and promises of more to come, everyone wants to know
how to reduce their electricity consumption. This can be done but
it is neither simple nor easy. In this article we will review some
strategies for saving power – and debunk some of the scams around!
T
he review of the FutureWave
Energy Saver for swimming
pool pumps in the June 2011
issue of SILICON CHIP has created a lot
of interest.
It really does work, unlike most
energy saving gadgets promoted to an
uninformed public.
There are two main types of energy
‘saving’ devices sold over the Internet,
at flea markets and unfortunately, by
some retailers who should know better.
Most are so-called power factor correction devices or devices which are
claimed to “clean up” or otherwise
fix your “dirty” or “unusable” power.
These provide no benefit to domestic
consumers and have been frequently
discredited. (See the November 2007
and May 2008 issues of SILICON CHIP).
Less common power saving products
are voltage reduction devices for electrical motors. They vary the voltage to
the motor, depending on the load. More
on these devices later.
Possibly some readers may have
suspected that the FutureWave device
reviewed in the June 2011 issue was
just another device varying the voltage
fed to the motor. But the review gave a
different picture.
It is intended for controlling swimming pool pumps which are driven by
22 Silicon Chip
induction motors.
The FutureWave reduces the supply frequency fed to the motor, as
well as manipulating the voltage and
waveform.
The end result is reduced motor
power consumption while still providing adequate torque and power output.
This is the real advantage of the
FutureWave compared to anything else
on the market.
It was determined by the developers
of the FutureWave Energy Saver, after
studying pump curves and graphs of
pool pumps and much testing, that
dropping pump speed below 1700
RPM, the resulting flow rate drops is
not adequate for effective filtering.
Hence the lowest flow setting on the
FutureWave is 31.5Hz, giving a pump
speed of around 1800 RPM (for a 2-pole
induction motor with a nominal speed
of 2850 RPM) and allowing flow rates to
be maintained to adequately maintain
filtering and cleaning performance.
On average. this will provide a
power saving of about 70%,
Where do the savings come
from?
The savings come about because
swimming pool pumps are over-specified for normal water filtering. The
FutureWave provides large savings
by reducing the flow rate through the
pool’s plumbing to a rate better suited
for efficient pumping and filtering.
So why is the pump not the ideal
size for normal water filtering? It is
basically because a larger pump with
enough power output is required to
prime the pool’s plumbing system, run
The FutureWave
Energy Saver was
reviewed back in the June 2011 issue.
It’s one device which really can cut
your electricity bill if you have a pool!
siliconchip.com.au
a pool cleaner and provide adequate
flow to perform backwashing.
The FutureWave allows the pump
to prime the pools plumbing system
before its energy saving mode kicks
in. It will then reduce the power consumption whilst providing adequate
flow rates to operate the pool cleaner
(eg, Kreepy Krauly). A pump has to be
able to pump 120-180 litres/minute
against a reasonably high ‘head’ (eg,
the depth of the pool plus height of
pump above the pool) to keep the
cleaner operating.
When the cleaner is not in use, ie,
when the pool water is simply being
filtered, the pump does not slow down.
It continues to pump hard, forcing lots
of water though the system.
This is not efficient because the friction loss in the PVC pipes of the typical
swimming pool rises as roughly the
square of the water flow.
So when you double the flow rate
the friction loss of a system increases
by a factor of four. In other words, you
need four times the power to pump 240
litres/minute around a pool system
compared to 120 l/min.
This was seen with figures given in
the June FutureWave article. A 40%
reduction in motor power frequency
and thus water flow gave over a 60%
reduction in power consumption.
Halving the water flow rate would
give a 75% reduction in pump energy
needs.
In effect, the FutureWave Energy
Saver converts a normal swimming
pool pump into a variable speed pump
that can be scaled to better meet water
pumping requirements, giving energy
savings when high water flow rates or
pressures are not needed.
Variable speed pumps
So why not simply use a variable
speed pump?
In fact, they are available, from most
swimming pool shops. A typical example is the Hydrostorm ECO which
has three speed settings (2850 RPM,
2410 RPM and 1900 RPM) and which
according to waterco.com.au can slash
its energy use by up to 67%. It costs
about $1,200. See: www.waterco.
com.au/pool-spa/11-hydrostorm-ecothree-speed-pumpThere are a range of other variable
speed pumps including the Zodiac
FloPro ePump which has up to eight
different speeds (www.zodiac.com.au/
products/pool-pumps/flopro-epump)
siliconchip.com.au
The all new ‘Dual’
Future Wave Energy Saver
We looked at this “Electicity Saving
Box” back in November 2007 and
proved it wasn’t even worth the box
it came in . . . nothing has changed,
except now there are lots more of
them around. Don’t believe the claims:
they’re a con!
and the HurlconViron P300. See
www.rodepools.com.au/content.
php?pageid=1276835758
These variable speed pumps all
use brushless permanent magnet motors which are driven by switchmode
controllers.
Not only do they have the advantage of lower power usage, they are
also substantially quieter than typical
pumps driven by induction motors.
That gives a further advantage in that
they can be run from off-peak power at
night without disturbing neighbours.
We should note that the developers
of the FutureWave Energy Saver have
pointed out that “while variable speed
brushless DC motor driven pumps
may claim over 70% savings, they also
mention that at the reduced pump
speed (600-800 RPM) the flow rate is
reduced to 80-100 litres/minute, well
below the required flow rate for a filter
and cleaner to perform adequately.”
From talking to people in the pool
industry it appears that customers are
reluctant to spend more on variable
speed pumps or on water filters, above
the minimum required.
The initial cost is an issue. A regular 750W (1 HP) pump typically costs
about $400-500 and a 1.5HP unit only
slightly more. Compare that to a new
variable speed pump which costs $500
to $1000 more to install.
In the past the running costs have
not been a major concern to customers at the time of the pool or pump
purchase.
Following on from the highly
successful single connection Future
Wave Energy Saver a dual unit has now
been developed and released.
Feedback from pool owners was
highlighting the growing concern that
a lot of pool owners are running more
than one pump to maintain and run their
pools. Along with the main filter pump,
pools are running extra pumps for such
tasks as solar water heating or to run
their pool cleaning systems.
Running extra pumps of course
means more energy usage and higher
costs.
The Dual Future Wave has been
developed with this in mind.
The option prior to the Dual unit was
to either have a separate Single Future
Wave on each pump or maybe only
run one Future Wave on the main filter
pump as it typically runs longer and
subsequently higher electricity costs.
The Dual Future Wave now offers a costeffective way to address this concern.
The Dual unit allows the filter pump to
be connected to the ‘Pump 1’ side with
the second pump connected to ‘Pump 2’
and can provide control over ‘Pump 2’,
not allowing it to start unless ‘Pump 1’
is running and also a time delay.
This is critical for solar pumps or
cleaner system pumps where they rely
on the main filter pump be running to
operate.
The Future Wave Energy Saver (Dual
& Single) with its ‘Flow Adjustment’
setting allows the pool owner to
perfectly match and achieve the
maximum energy savings to the
required output or flow rate of each
pump that it runs.
Please refer to the advertisement at
the end of this article for pricing and
contact details.
September 2011 23
Hydrostorm’s ECO pool pump and
filter – it looks similar to most
standard pumps but features a
variable speed motor.
But with skyrocketing electricity
costs, that is now changing rapidly
and people are likely to be far more
sensitive to electricity bills.
In practice many pools would be
better cleaned if they had a larger filter
and a smaller pump. Filtering works
best at lower flow rates.
We understand that Sydney pools
typically use 1HP pump motors with
1.5HP motors being mainly limited to
80,000 litre and larger pools.
It is also possible to separate pool
filtering and cleaning. Pool water filtering can be done with a smaller pump,
typically 0.5HP, with the automatic
pool cleaner running off a booster
pump when required.
Finally, for the lowest energy consumption, swimming pool shops sell
a number of electrically-driven pool
cleaners (often described as pool
cleaning “robots”).
These are powered by 24V DC motors and are very energy efficient. They
typically draw about 100-150W when
running.
A low-voltage (24V DC)swimming
pool “robot” cleaner. They’re claimed
to save money because they are not
reliant on a large pool pump working
hard to control them. They are
suitable for all sized pools including
large commercials.
24 Silicon Chip
Similary, the Hurlcon Viron P300 also
sports a variable speed motor. At
about $965 it’s not cheap but claims
power savings (at 2010 prices) of up to
$700 per year over conventional (ie,
constant speed) pumps.
Overseas experience
Oversized pool pumps are not just
an Australian problem. In a study of
120 pools by the USA Center for Energy Conservation at Florida Atlantic
University, some pool owners saved as
much as 75% of their original pumping bill by replacing large pumps with
smaller pumps and by simply reducing
running time.
The study showed that a 0.75 horsepower (600 watts) or smaller pump
is generally sufficient for residential
pools.
By the end of this year Florida will
ban the sale and professional installation of single-speed pumps of one
horsepower or greater for domestic
swimming pools.
Also, California has, as you would
expect, a large number of swimming
pools and has studied pool energy requirements in detail. See www.energy.
ca.gov/title24/2008standards/prerulemaking/documents/2007-02-26-27_
workshop/supporting/PGE-DRAFT_
REPORT_RESIDENTIAL_SWIMMING_POOL.PDF
In summary, the most economical
pool system is one designed for efficient water flow and fitted with a
variable speed motor.
The simplest option for most people
would be to reduce the filtering run
time for their existing pump as far as
possible and when the pump motor
is next replaced install a multi-speed
motor.
er electrical consumption, frequently
with impressive university reports
setting out the electricity savings. But
whether these devices actually save
money is another matter.
They are intended for use with
AC induction motors. They work by
monitoring the motor and lowering
the voltage when the motor is lightly
loaded.
The monitoring technique was developed by NASA engineer Frank Nola
to lower energy consumption in motors and fans on NASA-built vehicles.
NASA still lists it as a NASA technology spin-off. Details can be found on
the NASA web site www.nasa.gov
This concept generated a lot of interest during the 1990s and there were
many manufacturers of these devices,
claiming spectacular savings.
In simple terms, the device monitors the motor’s load by measuring
the power factor and then uses some
sophisticated electronics to control
the voltage to keep the power factor
constant even as the load changes.
This reduces the losses in the motor when the motor is lightly loaded.
Lowering the voltage of a synchronous
motor does not change the motor speed
but does reduce its torque.
The cleverness in Nola’s work was
how he used power factor changes to
automatically determine the required
The Blue Diamond
robotic pool cleaner
is claimed to clean the
average pool in about
three hours. It operates
from 24V DC and
consumes about 120W
– a fraction of the
power of pool
pumps.
Energy saving devices
As already noted, simple capacitorbased power factor correction boxes
do nothing in a domestic environment
as far as power saving is concerned.
But other devices can appear to lowsiliconchip.com.au
voltage adjustment so that power increased when more
torque was needed. Microprocessor-based integrated circuits are available to handle the device smarts, for example
the Microchip MTE1122.
A typical device sold to the public for domestic appliances is the Reegen uPlug power saver, marketed widely
around Australia in 2009.
Results on unloaded motors using this device can be
impressive. For example, tested it with a 0.3 HP drill
press motor, readings fell from consuming 190W to 145W,
an apparent 25% reduction. But operated under heavy
load – in other words, working as intended– it showed
NO power saving.
In a domestic environment they do not save money.
Tested on a wide range of devices such as refrigerators
and washing machines, there are minimal electrical savings
on most devices because their motors are already running
at close to full load.
In fact, the claimed savings all seem to be on motors running with no load. Details of some studies of these devices
with a range of motor sizes can be found at http://home.
clear.net.nz/pages/lmphotonics/es090698.pdf
Refrigerators are an interesting case and show that simply measuring the power consumption (ie, watts) can be
misleading. I have tested refrigerators that show a 5-10%
power saving on a commercial wattmeter.
But when total energy used over 24 hours is measured
there is no saving. This is because the refrigerator simply
ran for longer times when on the energy savings device. It
still had the same amount of work to do to cool the contents.
In summary, these devices provide no benefit in the
normal home, especially as they typically cost $200 to
36 days of free
electricity per year!*
Eliminates 100% standby energy of all connected
appliances
Easy access – ecoswitch® can be placed within easy reach:
no bending, straining or forgetting
Easy to use and install – even for the elderly and disabled
Pay-back period for the average household is less than 26
weeks*
Save over $120 per year off your electricity bills*
Save over 800kg of carbon dioxide per year*
Reduces fire risk
Longer life for appliances
Control your appliances from a new easy location of your
choice
No electronics inside to fail or emit nasty electronic noise
Safer than an ordinary extension cord
Double sided tape and clips keep cords tidy
Works with all 240V appliances (full 10 amps capacity)
12 month warranty
Unlike other energy saving devices, the ecoswitch®:
Doesn’t require programming, a remote control, or batteries
Can be used with your existing powerboard/s
Has a special flat plug that lets furniture sit closer to the wall
*estimated using 3 units per household
Visit www.ecoswitch.com.au for more information, or contact us at sales<at>ecoswitch.com.au
Factory is ISO9001 certified. Approved to Aust/NZ standards . Patents Pending.
Carbon Reduction Industries Pty Ltd ACN 128 270 388
ECO004 FastFacts.indd 1
7/10/2010 5:11:44 PM
The Micro Plug Power Saver: first released a couple of years
ago, these were supposed to connect to electric motors and
save you money. Did they work? On motors with no load, yes.
But how many motors run with no load? At $198.00 each, your
grandkids (or theirs) might see a payback . . . but we doubt it!
siliconchip.com.au
September 2011 25
$500. For an overview, see http://www.
bar-fridges-australia.com.au/pdf/reegenmicroplugpresentation1.pdf
Voltage optimisers
“Voltage Optimiser” devices are
another recent development. They
have appeared across Australia with
marketing targeted at clubs and small
businesses wishing to lower their
electricity bills.
The promoters claim to “reduce
electricity cost by up to 20%” by better
controlling the voltage.
The optimiser is frequently a transformer that reduces the supply voltage to the area or site. It is difficult
to see how installing these voltage
adjustment devices can save money
by themselves.
If simply lowering the mains voltage
to a device made a major difference to
energy consumption you would presumably have larger electricity bills
if you lived in an area with higher
voltages.
In Australia our electricity supplies
run at a nominal 230VAC but can be
anywhere between 216 and 253VAC.
Until 2000 the nominal voltage was
240VAC and there were a number of
studies done during the 1990s on what
impact a change of voltage would have
on typical domestic appliances.
In practice it was found that voltage
changes have minimal effect, particularly for motor-driven devices.
One particular study, that in the
1990s by the University of Ballarat,
which included substation monitoring, concluded that voltage variation
has minimal effect on energy usage.
For further information see http://
itee.uq.edu.au/~aupec/aupec04/papers/PaperID77.pdf
It stands to reason: simply lower-
ing the voltage to an air conditioning
unit does lower its power reading in
Watts – therefore you apparently use
less power – but to maintain the same
temperature, the unit now cycles so
that it is on for longer.
Total energy consumption and cost
will be unchanged.
In reality, it would be very difficult for customers to tell if voltage
optimisers really are giving a cost
saving. In particular, refrigeration or
air conditioning unit energy consumption depends heavily on ambient air
temperature.
There are any number of websites
where enthusiastic suppliers show
actual energy bills to “prove” their
point. But showing energy savings
by comparing electricity bills can be
simply showing different average air
temperatures.
For example, a colleague remarked
the other day that this past winter
(2011) is as cold as he can remember,
having used his air conditioner on all
but about ten nights. Compare this
with the mild winter of 2010, where
he recalled using the air conditioner
for ONLY about ten nights!
To my way of thinking the best way
to make a real saving is to adjust the
thermostat on the air conditioning to
be closer to the ambient temperature
and to turn devices off when they are
not needed.
The only case where these energy
devices are cost effective is where
motors run at well under their design
load for long periods, for example
escalators or conveyor belts that are
only intermittently loaded.
Escalators must be designed to allow
for two people on every tread – yet
they work day in, day out often with
virtually no-one on them. (Modern
This
intelligent
power meter from
Jaycar Electronics simply plugs into a
normal power point (GPO) and turns
it into a real-time power monitoring
outlet. You can enter the local price of
your electricity and the meter will tell
you exactly how much the appliance
is costing to run.
buildings often have escalators that
either stop or slow right down until
someone steps on them).
Similarly, conveyor belts need to
cater for worst-case scenarios but often
have significantly less than maximum
usage.So be very wary of any company
who claims that their device substantially lowers power consumption and
costs by modifying the mains voltage.
A reduction in power (Watts) will
almost certainly be offset by longer
running time. Total energy use (kWh)
and cost will be unaltered.
Lighting? Tiny savings are
possible
If reaching behind cupboards to turn things on and off isn’t to your liking (or
maybe the floor is too far away!) this Ecoswitch allows you to put the on/off
switch wherever you find convenient. It’s great for home theatre systems.
26 Silicon Chip
The only area where voltage does
have a more than minimal effect is
lighting, where power consumption
and light output are roughly proportional to voltage.
The newer fluorescent lights (both
compact fluorescent and those with
electronic ballasts) draw a constant
current and are much less sensitive
to voltage than incandescent lamps.
But the same saving can be obtained
by using lower wattage light bulbs.
What’s more, some bargain CFLs
siliconchip.com.au
can be responsible for a higher power
usage than quality, brand-name units
(although even this is not always the
case).
You see a lot of comment in the
popular media about turning lights
out when not in use but the truth is
that lighting represents only a tiny
percentage of overall household power
consumption.
Some other, admittedly marginal
savings can be made by reducing the
“on” time of sensor lights, particularly
outside floodlights which tend to be
a bit more power hungry. If whoever/
whatever caused them to trip is still
moving around out there, they’ll come
back on again!
Overall though, you’re not going
to save any real money by modifying
your lighting usage (with the possible
exception of large outside floodlights).
Standby power
It is estimated that a typical household uses up to 100W in standby
power – they’re all the things that are
turned on by remote controls, or by
pressing “soft start” buttons.
100W continuous adds up to about
siliconchip.com.au
875kWh a year and at (say) 25c/kwh,
will cost you a couple of hundred dollars or so a year.
So can you save this by turning everything off at the power point?
Yes you can – but you will often lose
a lot of convenience. Anything with
a clock may well lose its settings, as
may many other devices which rely on
standby power to keep their memories
active. Some devices, such as Foxtel
boxes, can take quite a while to reset
themselves.
It can be a real pain to have to reset
everything each time the power goes
back on!
But you can – and arguably should –
turn off quite a number of devices such
as computers and monitors, amplifiers,
indeed most home theatre equipment,
ceiling fans/lights, and so on.
Often it’s very inconvenient to reach
a power point to turn devices on and
off (another reason most people don’t
bother!) but Carbon Reduction Industries have a handy “Ecoswitch” which
brings the switch up to where it’s convenient. The socket end can connect
to powerboards, etc, if required (www.
ecoswitch.com.au).
Magic Bullets?
Sorry – there are no magic bullets.
In the end it is as simple as making
certain you understand where your
electrical energy is used and that any
inefficiencies are removed.
The best energy saving device you
can try is one of the cheap and cheerful
energy meters available from Jaycar,
Dick Smith and other stores. They
are reasonably accurate and include
power factor measurement.
Those tried are within 2% of commercial meters. Their main disadvantage is limited resolution in measuring
energy consumption (usually kWh, not
Wh) over a period and also some can
be “fooled” by complex waveforms
when measuring low-power switchmode devices.
In conclusion, there is only one
golden rule in assessing promised energy and cost savings: “Only energy that
is being wasted can be saved”.
SC
* This feature was inspired by, and largely
based on, a contribution by John Cameron,
with additional material by Leo Simpson
and Ross Tester of SILICON CHIP.
September 2011 27
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