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Tankless fuel cost calculator Estimator
Tankless Energy Calculator provided by Rheem Manufacturing

-Tankless Estimates made are for new water heater in perfect operating environment.
Tankless cannot be exposed to more than 11 grains hardness in water, or efficiency declines within 2 months.

-Tankless Estimates do not consider cost of repairs and cost of required yearly maintenance.

-Tankless Estimates do not consider behavior aspect of promising endless hot water. My experience shows that we use
more hot water when water heater timer is turned OFF, than when we have timer turned ON.
How much does water heater timer save

-Tankless Estimates are for factory-set 120 degree F. People likely set the temperature higher.
Fill in the blanks in the grey shaded areas. This comparison does not reflect stand-by heat loss; or recovery. 
This comparison is not a true reflection of energy use over time; only the costs to heat one tank of water from a cold start; 
and see how the 3 fuels compare.  This spreadsheet uses the actual calculations from the GAMA Directory.
Visit GAMA on the web at http://www.gamanet.org
Natural Gas ** To determine yearly cost multiply daily cost time 365
Volume of   Temperature BTUs EF rating BTUs   Actual
Hot Water H2O Weight rise in required of the purchased Cost per daily cost to
Heated   degrees F to water heater to heat therm heat the 
      heat water   water   water **
64 8.33 77 41,050 0.62 66,210 $1.2000 $0.795
Electric
Volume of   Temperature BTUs EF rating BTUs   Actual
Hot Water H2O Weight rise in required of the purchased Cost per daily cost to
Heated   degrees F to water heater to heat KW/hour heat the 
      heat water   water   water **
64 8.33 77 41,050 0.94 43,670 $0.0841 $1.076
BTUs are used to convert electric for comparion purposes. The math calculation is accurate for electricity.
Propane Gas
Volume of   Temperature BTUs EF rating BTUs Cost per Actual
Hot Water H2O Weight rise in required of the purchased gallon daily cost to
Heated   degrees F to water heater to heat propane heat the 
      heat water   water   water **
64 8.33 77 41,050 0.62 66,210 $1.2100 $0.875
Tankless
Volume of   Temperature BTUs EF rating BTUs Cost per Actual
Hot Water H2O Weight rise in required of the purchased gallon daily cost to
Heated   degrees F to water heater to heat propane heat the 
      heat water   water   water **
64 8.33 77 41,050 0.82 50,061 $1.2000 $0.656

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