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RESNET Adopts Formal Interpretation on Water Heater EF

Jul 12, 2016

A clarification was needed to resolve conflicting hot water heater EF specifications within ANSI/RESNET/ICC Standard 301-2014.

As specified in Table 4.2.2(1), the Energy Rating Reference Home is required to have service water heating systems with EF values set as follows:

  • Electric: EF = 0.97 – (0.00132 * store gal)
  • Fossil fuel: EF = 0.67 – (0.0019 * store gal)

However, footnote (n) to the same table required:

For a Rated Home without a proposed water heater, a 40-gallon storage-type water heater of the same fuel as the predominant fuel type used for the heating system(s) shall be assumed for both the Rated and Energy Rating Reference Homes. In both cases the Energy Factor of the water heater shall be as prescribed for water heaters by CFR 430.32(d), published in the Federal Register/Volume 66, No. 11, Wednesday, January 17, 2001 for water heaters manufactured after January 20, 2004.

To ensure that all fossil fuels use a consistent value for EF for the ANSI/RESNET/ICC Standard 301-2014, the RESNET Standards Development Committee (SDC) 300 has adopted the following formal interpretation:

Table 4.2.2(1) Footnote (n) shall mean that when a Rated Home has no proposed water heater, the assumed 40-gallon storage-type water heaters in both the Rated and Energy Rating Reference Homes shall use the Energy Factor formulae for the appropriate fuel class found in Table 4.2.2(1).

The effective date for the implementation of the interpretation will be July 20, 2016.

To view the formal SDC 300 interpretation go to Water Heater EF