RESNET Proposes Amendment on Instantaneous Water Heater Efficiency

November 11th, 2011 - Posted by RESNET under RESNET News

There is empirical evidence that instantaneous water heaters do not perform at their rated efficiency when compared to realistic hot water draw profiles. The U.S. Department of Energy’s (DOE) procedure for establishing the Energy Factor prescribes six equal, hourly draws totaling 64.3 gallons during the first 5 hours of a 24-hour testing period. Occupants more commonly make dozens of smaller draws throughout a day. Instantaneous water heaters are subject to significant thermal loss directly following a draw. The DOE procedure does not adequately capture the totality of thermal loses stemming from typical residential use. Based on results of lab and field testing conducted by the David Energy Group, the California Energy Commission adopted into California’s Building Energy Efficiency Standards the requirement that the code-compliance software apply an adjustment factor of 0.92 to the Energy Factor for gas, oil and electric instantaneous water heaters.

The RESNET Technical Committee has proposed an amendment to RESNET standards to adjust instantaneous water heaters efficiency.

The amendment is undergoing an ANSI compliant public review and comment process. Interested parties are encouraged to comment on the proposed amendment. Public comments on the proposed amendment will be accepted until Wednesday, December 14, 2011.

To submit your comments, click on Submitting Comments on Proposed Amendment

Comments are posted real time and you will be able to review comments that were submitted by clicking on Review Comments Submitted

To download the amendment, click on Proposed RESNET Standard Amendment

Only comments made through the online system will be accepted.

After the comment period, the appropriate RESNET committee will consider and document each of the comments submitted and make appropriate changes. The revised proposed amendments then will be submitted to the RESNET Standards Committee who will review the public comment process then recommend to the RESNET Board for adoption.

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