Demonstrating an Integrated Thermal Heat Pump System for Hot Water and Air-Conditioning at Full Service Restaurants.

In this paper the authors summarize data and key findings from the demonstration of integrated thermal heat pump (THP) systems, which are innovative "hybrid" commercial water heating solutions installed such that the THP provides (a) hot water in series with conventional water heater(s), and (b) A/C supplemental to the building HVAC. Major components are the THP, providing high-efficiency heating and 'free cooling' to separate hydronic/chilled water loops, an indirect storage tank in series with conventional water heater (s), and an indoor cooling coil installed as standalone or within the ductwork. At its core is the THP, a direct-fired absorption heat pump providing hot water and A/C through a four-pipe design, with additional flexibility to operate as an air-source THP during periods of low or no A/C demand. Of the estimated 340 million therms per year consumed for commercial hot water in California restaurants, most are consumed by low-efficiency water heaters with a thermal efficiency of ~80%. With an estimated improvement of operating efficiency to 140% or greater for hot water production, broad deployment of THPs could reduce natural gas consumption for commercial water heating in restaurants by 43%, while displacing up to 20% of electricity demand for A/C, providing further energy and operating cost reductions. This potential is assessed in a year-long demonstration of prototype integrated THP systems at two restaurants in Los Angeles, CA, summarizing system design and optimization, energy savings over a broad range of operating conditions, retrofit installation barriers, and interactive effects with other building systems. [ABSTRACT FROM AUTHOR]