Estimating Electric Power Consumption of Grid-Enabled Residential Heat Pump Water Heaters

We present two methods for estimating compressor electric power consumption of residential heat pump water heaters. Power is calculated using data from voltage and current instrumentation, which add costs and potential failure points to the unit. The two methods presented herein use thermal instrumentation or derived data that are typically included within modern residential heat pump water heaters. One method uses data from lower and upper tank temperature sensors. The other method uses an attribute that is commonly available within grid-enabled flexible load heat pump water heaters. For both methods, fit equations were derived, for which coefficients are tuned to achieve a reasonable fit between estimated and measured electric power consumption. Within this paper, we describe the fit equations and the methods for tuning the equation coefficients. We also present metrics of fit between measured and estimated power consumption, sensitivity analyses of the fit equation coefficients, and validation analyses of a tuned fit equation using multiple data sets.