Water and Space Heating Heat Pumps

Abstract

This paper discusses the design and operation of the Trane Weathertron III Heat Pump Water Heating System and includes a comparison of features and performance to other domestic water heating systems. Domestic water is generally provided through fossil fired heating units or electric resistance water heaters. When electric resistance water heaters are utilized there are three alternative electric heating concepts available to reduce home energy consumption. They are desuperheaters, dedicated heat pump water heaters and the Trane system Weathertron III. Desuperheaters offer low cost with good payback and low investment requirements. Dedicated heat pump water heaters do not require integration with an air conditioning system. The Weathertron III system is an integrated air conditioning, heating and domestic hot water heating system. This system provides demand hot water heating. It has the best savings and good payback with high recovery capacity. Also, the free cooling provided during water heating can provide additional dehumidification in warm humid climates typical of Texas coastal areas. The basic components of the Trane Weathertron III system are the outdoor unit, indoor air handler, water heating unit and computerized control center. Unique aspects of the Weathertron III system design and operation are described in United States Patent No. 4,299,098, 4,399,644 and others pending. A significant feature of the invention lies in the fact that during operation in any particular mode, the inactive heat exchanger of the circuit is vented to the suction side of the compressor, so as to afford proper refrigerant control within the system. Annual operating cost savings vary from 27% to 36% for the three systems with the Weathertron III having the most. When compared to a conventional all resistance heating system and a conventional heat pump system, the Weathertron III can save 24% to 49% of the space conditioning and water heating energy used in a home.