The thermal performance of residential electric water heaters subjected to various off-peak schedules

Journal Article · Wed May 01 04:00:00 EDT 1996 · Journal of Solar Energy Engineering

DOI:https://doi.org/10.1115/1.2848010· OSTI ID:250786

Fanney, A H; Dougherty, B P ^[1]

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1. National Inst. of Standards and Technology, Gaithersburg, MD (United States). Building and Fire Research Lab.

An increasing number of utilities control the supply of power to residential water heaters as one means of reducing peak electrical demand. Water heaters operated in this manner are referred to as off-peak water heaters. Several utilities are also considering the use of solar domestic water heaters as an additional means of limiting power demand during times of greatest electrical usage. The research described within this paper quantifies the variation in thermal efficiency attributable to subjecting residential electrical water heaters to various off-peak and water removal schedules and, thus, forms a basis of comparison to which the thermal efficiency of solar water heaters or other water heating technologies may be compared. Laboratory tests, where the off-peak period and hot water draw schedule were varied, were conducted on two residential storage water heaters. A computer model of an electric water heater was developed and validated. The laboratory tests and the model were used to quantify the effect that various off-peak and hot water draw schedules have on water heater thermal efficiency. Thermal efficiency was found to vary up to seven percent for water heaters which meet the present minimum efficiency standards as specified within the National Appliance Energy Conservation Act. The energy factor, as measured using the Department of Energy Test Procedure for Water Heaters, is shown to be independent of the off-peak schedule because of a ``normalizing`` that occurs as part of the calculation procedure.

• Sponsoring Organization: USDOE
• OSTI ID: 250786
• Journal Information: Journal of Solar Energy Engineering, Journal Name: Journal of Solar Energy Engineering Journal Issue: 2 Vol. 118; ISSN JSEEDO; ISSN 0199-6231
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
ELECTRIC UTILITIES
LOAD MANAGEMENT
PEAK LOAD
PERFORMANCE
RESIDENTIAL BUILDINGS
SOLAR WATER HEATERS
THERMAL EFFICIENCY