ENERGY SAVING
Fix your cistern to save power
Y
ou may be able to save
electricity by making an
alteration to your toilet
cistern. Sounds impossible?
OK, there are a few observations first, but here's how.
It presupposes your house
water supply is fed, like many
smallholders' houses are, via a
pressure pump. And that your
toilet cistern is fitted with an
old-fashioned floating ball
valve.
Here's the theory. When you
flush your toilet and the
cistern starts to refill, the
pressure switch on your
pump senses the drop in
pressure in your water system
and instructs the pump to
switch on. And here's the
kicker: A water pump is
driven by an electric induction motor, and an induction
motor uses up to three times
its rated power as it starts up.
(If you have a back-up
generator you'll have
noticed how it takes
strain for a second
or two when your
pump comes on.
C
That's the extra
power it's supplying
to the motor.)
Now while the flow
of water into the
B
cistern fitted with a
ball-valve is quite
fast to begin with, as
A
the cistern fills the
ball-float slowly
squeezes down on
the washer in the
valve, gradually
cutting off the flow
of the water, until
Modern energy-saving cistern valve. When
eventually
it ceases
water flows over the rim of the outer cup (A) it
causes the inner cup (B) to float, in turn exert- to flow altogether.
ing an upward force on the cut-off lever (C)
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In this situation there may be
two or three times when the
pressure in your piping is
sufficient for your pressure
switch to tell the pump to
switch off, only to have the
pressure gradually drop, and
switch on again, as the last
few litres enters the cistern.
So if you could reduce the
number of times your pump
switches off and on again to
compensate for the slowly
dropping pressure, you
would save the power surge
required each time by the
motor, and thus save
electricity.
And you can do that simply
by replacing your ball-valve
mechanism by a more
modern cup-valve.
This mechanism effectively
has two cups, one inside the
other. The outer one is the
right way up while the smaller
inner one is upside down, its
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