Water-cooled heat pumps: energy savers

An exception to the generally accepted rule that heat pumps save energy is used to illustrate how to avoid misapplications of hydronic heat pumps. A crucial consideration is whether the volume of water in the system's closed loop can maintain a temperature that is compatible with the individual heat pumps. Five alternative systems are analyzed and applied to a seasonal profile of a school load to compare energy efficiency and cost effectiveness. A water-cooled system is found to be justified on a life-cycle cost basis when the building requirements specify a low sustained cooling load, a small-capacity system, significant operating time when heating and cooling are simultaneous, and when there is no alternative to electric heat.