ter heater. Learning how
to use hot water more efficiently not only reduces
current and future water-heating costs, it can also
allow you to install a smaller, and therefore less costly,
solar water heating system. The monthly energy savings
resulting from conservation steps can be applied to
paying for a future solar water heating system.

The steps to efficient hot water use begin with
simple tasks that only need to be done once to save
energy for years to come.

1. Turn Down the Thermostat

Turn down the thermostat on the water heater to
115
o
F or 120
o
F. The unit will still provide hot water but
will use substantially less energy. For example, a typical
52-gallon water heater set back from 140°F to 120°F
will save 410 kWh/year of electricity or about 17
therms/year of gas.
1
At $0.07/kWh, $28.70 would be
saved, and at $0.60/therm, $10.20 would be saved,
every year. Saving this much energy would reduce the
size of solar collector needed by up to 10 square feet.
This would result in significant savings, considering
that a 52 square foot collector area, composed of two
4-foot by 6.5-foot collectors, retails for about $1030,
whereas a 4-foot x 10-foot, 40 square foot collector
retails for about $655.

Adjusting the Thermostat on a Water Heater


To turn down the thermostat on an electric water
heater, first switch off the circuit breaker for the
heater before removing the cover plates over the
thermostats. Electric water heaters typically have an
upper and a lower element. Set the upper thermostat
five degrees higher than the lower one. For gas water
heaters, the fuel doesnt have to be turned off to
adjust the thermostat. Simply turn the knob. In either
case, gradually adjust the temperature over a period of
days until you find the minimum satisfactory setting. If
you use a dishwasher, its cleaning power may be
affected by lower water temperatures. If your
dishwasher has an electric water-heating booster, that
may compensate for the lower incoming water
temperature.

Note: If it seems that you run out of hot water too
quickly, your tank may have a broken dip tube (a tube
that extends inside the tank from the cold water inlet
to the bottom section of the tank). This is not
uncommon and can easily be repaired by disconnecting
the cold water supply line, removing the old dip tube,
and replacing it with a new one (available at most
hardware stores).

2. Insulate the Water Heater
Most water heaters have only one or two inches of
insulation and adding an additional two to six inches can
produce significant savings. You can buy a tank
insulation kit or simply wrap the heater with six inches
of fiberglass insulation. Tie the insulation with wire or
cord and seal the seams with duct tape. Be sure not to
obstruct the pressure-and-temperature relief valve at
the top of the heater. On electric water heaters, cut
out a plug of insulation over each thermostat, allowing
easy access to the thermostat adjustment knobs. The
insulating plug can be reinserted after the tank is
wrapped. For gas fired heaters, make absolutely sure
not to cover up the combustion air intake vents at the
base of the unit. Also leave a gap a couple of inches
wide between the insulation and the flue pipe at the
top of a gas or oil heater. Insulating your water heater
should take less than an hour and should cost $10 to
$30. Within a year the insulation will save you this
much on your electric or gas bill.

A slightly more expensive, but possibly more
aesthetic, option would be to wrap two layers of
Reflectix aluminum foil/bubble-pack insulation
around the water heater. In tight spaces the Reflectix
may be easier to install than fiberglass.

3. Prevent Heat Loss through Plumbing
Insulate exposed hot water pipes with pipe
insulation rated R-4 or better. (Dont bother with pipes
buried in walls - its not worth the trouble of ripping
apart walls.) Also insulate cold water supply pipes six to
eight feet from the hot water tank. This will reduce
heat loss from pipes and will at times allow hot water to
flow immediately from the taps (alleviating the need to
wait while cold water is flushed from the lines).
Install heat traps on the cold and hot water
connections to the water heater. Heat traps are check
valves that prevent heat from migrating by natural
convection into service pipes when in standby mode.
Some look like a simple ball-check valve. A 360-degree
loop in the piping can also serve as a heat trap.
2
Many
newer water heaters are now sold with heat traps.

Chapter Nine
Water Conservation and Energy Efficiency 60 Water Conservation and Energy Efficiency
4. Install a Timer on the Water Heater

If you only use hot water during one or two distinct
periods during the day, energy can be conserved by
installing a timer. The timer will turn the heater on and
off around those times of peak use. While one study by
the Florida Solar Energy Center (FSEC) found the
savings from using a timer to be minimal ($0.21/
month),
3
other studies have found substantial savings
from the use of timers. These different findings may
be due to factors such as hot water use schedules,
water heater thermostat set-points, the temperature
in the room where the water heater is located, water
delivery temperatures, the cost of heating and cooling
energies, and whether the water heater is also used
for solar storage.
4


Using a Timer in a Solar Water Heating System

Timers can be beneficial in solar water heating
systems that use a single electric tank. Try to buy the
tallest tank available with the proper volume,
disconnect the bottom element, and install a water
heater timer to control the operations of the upper
element. (These specifications are difficult to achieve
with a natural gas- or LP-burning water heater.)
Especially in households where the major demands for
hot water (i.e. pre-school and pre-workday showers,
dishwashing, etc.) occur in the morning, set the timer
to prevent the heater element from reheating water
before the sun can accomplish its heating. For optimum
timer operation, the element should be shut off
BEFORE the start of early morning hot water demand,
so that the coolest water is sitting in the tank, ready
to be heated later by the sun. The timer's next on-
cycle can be easily adjusted to ensure adequate hot
water for the next major period of hot water use, like
evening showers or dishwashing when everyone is home
from school or work.

Since electric water heater timers offer at least
two on-off cycles per day, you can easily turn the
heater off again in the evening, to reduce standing
losses when everyone is asleep. As with morning
operation, it is most efficient to heat up the water
right before it is needed, then make sure there is no
reheating during the actual hot water use. Unless hot
water use is so large that reheating during use is
necessary to keep pace with demand, a well insulated
tank will typically keep the water hot long after the
heating elements are turned off. For more casual hot
water needs, like mere hand washing, where warm
water is usually adequate, no periodic reheating is
required, if the water heater and pipes are well
insulated.

If you are interested in reducing your demand for
electricity during utility peak demand periods, you can
also use timers to schedule major backup water heating
between midnight and dawn when most electric utilities
experience their lowest electric demand. Although not
uniform in all areas, electric utility systems commonly
experience their peak electric demand in early
mornings and early evenings during the heating season,
afternoons and early evenings during the cooling
season.

5. Install a Non-Electric Flue Damper
For gas-fired water heaters, install a non-electric
flue damper, which opens automatically when the hot
exhaust from the gas burner flows up the tank. One
model available from Advanced Conservation
Technologies is priced around $50. The American Gas
Association tested a water heater with no hot-water
demand (it simply maintained a set water temperature),
and found that the damper reduced heat loss per hour
by 45 percent.
5

6. Use Less Hot Water
Reduce hot water consumption without sacrificing
convenience by using more efficient fixtures,
appliances, and other strategies. Saving hot water
doesnt necessarily mean taking fewer or shorter hot
showers. Changes can be made that will go mostly
unnoticed, except for the monthly savings in energy
costs, which can range from 25 to 50 percent.


First, install low-flow showerheads and faucet
aerators throughout your home. Low-flow showerheads
can dramatically reduce water consumption in showers
while still providing a powerful and comfortable spray.
These low-low fixtures are inexpensive, easy to install
(they just screw onto the end of existing fixtures), and
can be found in most hardware stores.
Second, consider washing laundry with cold or warm
water rather than hot water. Use hot water only when
truly necessary, and look for detergents designed for
washing with cold water.
Third, when you buy a new washing machine, consider
buying a high-efficiency model. Look for the Energy
Star label to help you identify washers that use water
and energy most efficiently. These washers can
produce dramatic savings in energy and water use.
Fourth, check the water pressure coming into your
house. You can do this with a pressure gauge (available
from most hardware stores) that can screw onto a hose
faucet fixture. If the pressure is continuously above
45 pounds per square inch (psi) you could reduce your
hot water use by installing a pressure-reducing valve.