Electric Tankless Water Heater Savings
A conventional tank water heater is one of the largest energy users in homes and businesses,
accounting for approximately 25 - 35% of the electricity consumed. Part of the reason for
this is because a tank heater continually heats water whether or not it is actually being used.
Tank heaters require you to heat the stored water to an exceptionally high temperature in order to
provide an adequate supply of hot water. This temperature is typically far higher than what
would be comfortable or safe for showering or other household uses. You must first pay to heat
this water only to cool it again by adding cold water to make it comfortable for
use. In other words, you are paying for electricity which heats the water to a much
higher temperature than you will ever actually use. Furthermore, you must pay to keep the water
in the tank hot all day, not just for the few minutes of each day that it is actually needed. This results in a substantial amount of wasted
energy - and wasted money too!
The solution?....A Tankless Water Heater....
The Tankless Concept
Expenses related to heating water represent the largest portion of residential utility
bills (up to 30%). By heating water on demend as it is needed, and only to the temperature that it will actaully be used, Stiebel Eltron Tempra Series tankless water heaters provide unlimited hot water for full house use, offering potential savings of up to 50% of water heating bills in residential applications and even greater savings in commercial applications.
Instead of requiring a 30-80 gallon storage tank, Stieble Eltron tankless water heaters operate on
demand by heating water as it flows through an appliance roughly the size of a brief case.
Stiebel Eltron Tempra tankless water heaters utilize energy only when the hot water outlet is turned on, shutting
down immediately when the outlet is turned off.
The Inefficient Conventional Tank Water Heater
Traditional electric or gas tank water heaters ("conventional heaters") have been used in
commercial and residential properties since the early twentieth century. Conventional heaters
utilize a simple heating element and tank technology that, with the exception of some fairly
recent gains in the area of energy efficiency, have remained virtually unchanged over the years. Conventional heaters require a substantial amount of space; generally located in utility rooms or garages, they consume valuable square footage that could be put to better use. Most conventional heaters have upper and lower heating elements, one of which is cycling on or off 24 hours per day, even when you're not at home.
Conventional Heaters are pre-set at temperatures that are so hot that scalding is possible,
and when water reaches the tap, cold water must then be added so that the temperature is
comfortable to human touch. This process of heating water is an extremely inefficient use of
valuable energy, not to mention a waste of water and money. When a hot water faucet is
activated, the conventional heater is at the same time replenishing the tank supply with
cold water, thereby lowering the overall water temperature in the tank and triggering the
element to draw more power to re-heat the water to the desired set temperature.
Because of this inefficient process, if you have, for example, a 60-gallon tank, you
actually only have about 45 gallons of useable hot water. The other 15 gallons are lost as cold
street water is added to the tank during the usage process.
In addition, a conventional heater is consistently radiating heat (loss), which also
contributes to the re-heating rate and energy consumption. This type of heat loss is often
referred to as "stand-by" heat loss. Simply by eliminating stand-by heat loss alone, energy
consumption can be reduced by 20% to 30%.
Stiebel Eltron Tempra Tankless Water Heater Vs "Conventional" Storage Tank Water Heaters
The following comparison was based on a family of 4.
Assuming 4 daily showers, 2 hand
washing applications per person, 1 hand dishwashing based on filling the sink and 4 bathroom
sink usages per day. Total of 93 gallons of hot water used per day. Amounts are in Canadian dollars.
||GE Electric (40 gal)
||GE Natural Gas (40 gal)|
||GE Electric (50 gal)
||GE Natural Gas (50 gal)|
*These Energy Factors are present in new appliances, a conventional
electric tank will perform at 80% efficiency after the first year
and degrade slowly thereafter. The Stiebel Eltron Tempra Tankless Water Heater
is rated an incredible 99% efficient for the lifetime of the heater!
**ADD $150-$200 /year if you rent your tank.
$0.0719 per kWh for electricity is the SW Ontario average electricity
These comparisons are based on the U.S. Department of Energy Hot Water Usage Guidelines as reported on the Energy Efficiency and Renewable Energy Clearing-House.
$0.38 per cubic meter for gas is the regulated Consumers Gas natural gas
supply rate (Jan 2001), included is a $10.00 per month service charge.
Hot Water Usage Estimates:
Average shower (10 minutes) - 20 gallons
Average clothes washer (one load) -- 10 gallons
Average dish washer (one load) -- 6 gallons
Average faucet flow -- 2 gallons/minute
Total average daily usage is 64 gallons per day
Tank Temperature setpoint of 135 °F, inlet water temperature of
-- °F and 365 day a year use.
Energy Factor and Average Annual Operating Costs based on D.O.E. (Department of Energy) test procedures.