In-Field Test Results of Heat-Recovery Units and Heat Pumps for Domestic Water Heating. Residential Conservation Demonstration Program

摘要

A field experiment was carried out to examine the relative advantages of air-conditioning heat recovery units (HRU's) and dedicated heat pump water heaters (HPWH's) as energy conservation devices. HRU's were retrofitted to six central Florida residences, three of these with additional 80-gallon preheat water storage tanks. The other three residences were equipped with HPWH's which could be operated alternatively to the HRU's. The systems were instrumented with Btu meters and kWh meters to measure the required water heating energy, the energy supplied by either the HRU or HPWH, and the energy provided as backup to either the resistance coils or the HPWH. Data was logged on magnetic tape every 15 minutes and computer interpreted for analysis. The method of installation and the modes of operation are discussed. Problems with the energy conservation equipment and the instrumentation are reported. Results are presented in terms of daily distributions of energy supplied, energy use, and energy saved for water heating in each of the six residences. Hourly distributions of energy required and HRU supply are provided to allow examination of the time-wise mismatch between air-conditioning waste heat availability and hot water demand. Projections of annual energy savings are made and suggestions for maximizing the performance of the HRU's are discussed. A simple payback analysis is done on the HRU's and HPWH's based upon observed performance, present day installed costs, and cost of displaced electricity. (ERA citation 09:002619)