Calculation Factors:

Rinnai operating cost is based on DOE efficiency standards and the average retail cost for natural gas for your state. This information is derived from the US Department of Energy (DOE) statistics updated April 1, 2007.

Gas fired existing tank efficiencies are calculated at an energy factor of .58 and based on the average retail natural gas prices for your state as of April 1, 2007 (source US DOE).

Existing electric tank efficiencies are calculated at an energy factor of .93 and based on the average retail electric gas prices for your state as of May 1, 2007 (source US DOE).

Existing hot water energy cost utilizes the following information for each state:

• The number of single family housing units per US census data updated to 2005
• The US Energy Guide label load estimates for hot water usage for an average household
• We calculate estimates based on the portion of existing water heaters that are natural gas or electric fired. We do not consider savings totals available from converting other hot water heating fuels such as oil or LP gas because nationwide pricing data is unreliable and alternate fuels typically represent a small share of the water heating market.