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How to save energy and money - build a timer
for your electric water heater for less than $50
To start with, this project may not work out for you if you have a large family that needs access to
hot water at many different times throughout the day.  But my wife and I live by ourselves, with only
3 cats and a couple parakeets to support (we kinda like it that way!).  Thus, we generally have a set
routine in which she showers early in the morning, and I take mine late in the evening.  Other than
that, all we really need hot water for is washing dishes after supper.  

Since electricity is more expensive between 12 noon and 5 o'clock, it's best not to operate the
water heater during these times - not to mention running it all night when we don't need it.  I have
come up with a way to turn our water heater off, except when we will be using hot water.  With this
timer, we've cut the water down to a few hours per day instead of it running continuously.

This timer is constructed using standard available materials.  The only somewhat specialized part
is a contactor for an outdoor air conditioning unit, which can be found at Home Depot or any
electrical supply store.  Unfortunately, most HVAC supply houses will only sell to the industry, so
it's good that you can purchase this contactor at a more society-friendly place.
Description of operation:
The heart of the timer is a standard wall timer that you plug into the wall outlet, then plug a lamp into so you can
set the times the lamp goes on and off.  Any timer of this type will work just fine.  The wall timer allows you to set
the turn-on and turn-off times, then sends the 110 AC line voltage to the lamp when light is called for.

Of course, this line voltage is not enough to operate a 240 volt water heater.  For one thing, the water heater
requires  TWO "hot" legs (each consisting of 110 volts AC) along with the safety ground, whereas your 110 line
voltage only has one hot leg, with the other prong being neutral (also connected to the ground prong inside the
breaker box).    Secondly, your water heater demands a LOT more current than a wall timer could possible provide,
and you would likely cause a fire if you tried running the timer output voltage into your water heater - the excess
current draw would melt it within minutes, and the circuit breaker may not sense enough current to kick off.

This is where the AC contactor comes in.  The contactor is designed to switch both legs of the high-current 240 volt
line, which supplies your water heater.  So, we are going to wire the wall timer to energize the contactor, which will
then safely switch the 240 volts to the water heater.  NOTE:  The coil in most contactors is designed to operate
on 24 volts AC, the standard low voltage level in Heating and Cooling.  You can also find contactors with a 110 volt
coil, but they aren't as easy to locate in the average home improvement supply house.  IF YOU CAN'T FIND A
CONTACTOR WITH A 110 VOLT COIL, YOU MUST ALSO PURCHASE A TRANSFORMER TO CONVERT THE
110 VOLTS FROM THE WALL TIMER TO THE 24 VOLTS REQUIRED BY THE CONTACTOR COIL!

From here, simply find a way to supply 110 volts to the wall timer (which is best mounted close to the water heater),
then wire an AC plug to plug into the wall timer and supply either the 110 volt contactor coil, or the 24 volt transformer
which will then feed the contactor coil.  Then it's just a matter of inserting the contactor into the 240 volt circuit,
with the high-current contacts interrupting power to the water heater.  Then set the wall timer for the times you
want the water heater to turn on and off, and the timer will do the rest.  Remember that your water heater will not
heat the water immediately - so you'll need to set it to turn on about an hour BEFORE  you'll need hot water.

But you can also set it to turn off about an hour BEFORE you won't need hot water anymore, since your water
heater will keep it nice and hot for a few hours after it turns off.  For instance, if you plan to shower around 7 PM,
you can set the wall timer to turn ON around 6 PM, and the water should be nice and hot by 7 PM.  It will take a
little experimenting to get the times where you want them, but you'll save a pretty nice chunk of money by not
running your water heater except when you will actually need hot water.

Each installation will be different depending on the location of your water heater, nearby available voltages, etc.
You may need to run a separate 110 volt line to somewhere close to the water heater, or you may already have an
outlet close enough to plug the wall timer right in.  ALWAYS FOLLOW LOCAL AND NATIONAL BUILDING CODES
WHEN INSTALLING AND MODIFYING YOUR HOME WIRING.  I strongly suggest encasing all wiring in conduit,
and using proper junction boxes to house the AC contactor and wiring junctions.  And of course, TURN OFF THE
BREAKER TO BOTH THE WATER HEATER CIRCUIT, AND THE CIRCUIT YOU'RE USING FOR THE WALL TIMER!

NOTE:  The contactor can produce a loud hum when energized, so it's best to locate it where it won't be heard.