This paper is based on a study of heat pump service life (age at replacement) . The objective of the study was to survey known heat pump owners who had installed heat pumps between 1964 and 1974, gather empirical data that would provide responses to a series of questions concerning the service life of the known heat pump or, if appropriate, the successor, and determine the factors that influence the replacement decision . The major findings include the following :

1. Between 96% and 98% of the respondents surveyed still had heat pumps;
2. A large percentage of the original units are still in operation;
3. The median age of replacement is approximately 20 years in Alabama.

Units: I-P