4560 -- Heat Pump Life Revisited PDF

A series of studies of heat pump service life were performed in the early- to mid-1980s, beginning with a survey in Alabama in 1984 (Lovvorn and Hiller 1985; Pientka 1987; Bucher et al. 1990; Lovvorn and Hiller 1987). The current paper describes results of a follow-up heat pump life survey performed in Alabama in 1997, some 13 years after the original study. This follow-up survey was performed more than ten years after the original work, so equipment survival curves could be reexamined after a greater number of units had been replaced. Major findings of the current study include the following:

1. Median heat pump service life in Alabama is approximately 20.5 years, which is nearly the same as in the 1984 study.
2. Average age at replacement of units that had been replaced increased to 18.2 years, up from 13.5 years in the 1984 study—this increase was expected because a greater number of units have now been replaced and the survey population age has increased.
3. Approximately 63% of units removed from service were still operational, up from slightly less than 50% in the 1984 study.
4. Approximately 90% of sites still had heat pumps.