Ground Loops for Heat Pumps and Refrigeration

Abstract

Ground loops are used for water source heat pumps. Refrigeration can be put on a ground loop. Water-cooled condensing units are more efficient than air-cooled, and they can be put indoors. Indoor location makes piping for desuperheater hot water easy. Since refrigeration equipment runs more than heat pumps, energy savings can be large for ground-coupled refrigeration. The paper presents a design procedure for ground loops for heat pumps, hot water, ice machines, and water-cooled refrigeration. It gives an overview of the commercial ground-coupled systems in Louisiana that have both refrigeration and heat pumps. Systems vary from small offices to a three-story office building with 187 tons. A chain of hamburger outlets uses total ground-coupling in all of its stores. A grocery store has ground-coupling for heat pumps and refrigeration. Desuperheaters provide 80 percent of the hot water for a coin laundry in the same building. A comparison of energy costs in a bank with a ground-coupled heat pump system to a similar bank with air-conditioning and gas for heat revealed a 31 percent reduction in utility costs for the ground-coupled building. Two buildings of the Mississippi Power and Light Co. have ground-coupled heat pumps in one, and high efficiency air source heat pumps in the other. Energy savings in nine months was 60,000 kWh (25 percent), and electric peak demand was reduced 42 kW (35 percent).