指出与其他形式的空间调节相比，地源热泵（GSHP）可以显著降低供暖和制冷成本。直接膨胀式地源热泵使用埋地制冷剂管道从地面吸热。注意到对这项技术的调查，旨在使这些系统更经济实惠。使用三个埋在地下的铜管沟（55米）对其进行了测试。该装置在2.85的性能系数下产生约8千瓦（27600 Btu/h）的热量。螺旋接地线圈占据了传统地源热泵设计所需的大约一半空间，使该产品更容易为改造市场所接受，因为现有的土地使用可能会妨碍传统地源热泵的安装。关键词:热泵，美国，土壤热泵，铜，测试，性能系数，成本，经济性，现代化，空间要求。 引文:研讨会，ASHRAE交易，第97卷，Pt。1991年，纽约

States that ground-source heat pumps (GSHPs) can significantly reduce heating and cooling costs relative to other forms of space conditioning. Direct expansion GSHPs use buried refrigerant piping to extract heat from the ground. Notes an investigation of this technology in an effort to make these systems more affordable. Describes a system using spiral copper ground coils buried in three 17 m (55 ft) trenches which has been built and tested. The unit produces about 8 kW (27,600 Btu/h) of heat at a coefficient of performance of 2.85. The spiral ground coil takes about half the space needed for a conventional GSHP design, making the product more acceptable to the retrofit market, where existing land use may preclude a conventional GSHP installation.KEYWORDS: Heat pumps, USA, soil heat pumps, copper, testing, coefficient of performance, costs, economics, modernising, space requirements.