Thermal Performance of Residential Electric Water Heaters Using Alternative Blowing Agents.
Thermal Performance of Residential Electric Water
Heaters Using Alternative Blowing Agents.
(1923 K)
Fanney, A. H.; Zarr, R. R.; Ketay-Paprocki, J. D.
ASHRAE Transactions 2000, Vol. 106, No. 2, 1-13, July
2000.
Keywords:
water heaters; blowing agents; efficiency; insulation;
heat loss; residential buildings; thermal conductivity
Abstract:
This paper presents the results of a study designed to
quantify the performance of water heaters insulated
polyurethane foams using three different blowing agents
-- hydrochlorofluorocarbon R-141b, H2O/C02, and
hydrofluorocarbon R-245fa. The thermal conductivity of
the foam was measured as a function of mean temperature,
using a guarded hot plate apparatus. Electric
residential water heaters, insulated with the three
polyurethane foams, were tested to determine the
influence of the blowing agent on the water heater's
energy factor and overall heat loss area coeficient. A
relationship between the overall heat loss area
coefficient and energy factor was developed and compared
to experimental results. An infrared imaging system
revealed that areas surrounding the heating element
access covers, the lower circumference of the water
heater and piping penetrations were significantly higher
in temperature than the exterior surface of the water
heater.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899