Life-cycle costs of air-source heat pumps?
jklump
| Posted in Mechanicals on
We have installed individual and central (VRF) heat pump systems in several of our affordable housing projects (multi family). I would like to be able to develop a replacement reserve based on the actual service life of the heat pump system and its components. I realize they have not been used in the US for that long but does anyone have data on how long these systems last. Thanks for any help.
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Replies
Julie,
According to the U.S. Department of Energy, "The lifespan of a central air conditioner is about 15 to 20 years." For the purposes of developing a replacement reserve account spreadsheet, I think that you can assume that the longevity of a ductless minisplit system is in the same range.
I used to do capital needs assessments for non-profit housing agencies, and most projects had replacement reserve accounts that were woefully underfunded. Do your project a favor, and assume a lifespan of 15 years.
Martin's estimate of 15 years sounds about right, but could be on the short side. It varies by manufacturer (a LOT, if you're looking at second & third tier vendors). A pretty-good Daikin / Mitsubishi / Fujitsu should go a good 15 years between repairs with minimal maintenance, 20-25 years before replacement rather than repair would be in order.
The outdoor unit's coils are susceptible to salt air degradation in ocean side installations. I'm not sure what the mean time between replacement would be in a salt air environment, but probably less than 15 years. The indoor and outdoor units can be purchased separately.
Folks with three shaggy dogs who eat only fried foods and never clean the filters might not make it five if the coils on the interior unit is constantly plugged. Cleaning a totally clogged up wall-coil usually requires removing the head and re-installing it post-cleaning.
Don't have hard data on this, only verbal feedback from folks who have been installing them for awhile now.
I recently heard of a DIY-installed Gree unit failing in less than 2 years, but that's probably an outlier, and the failure mode was unspecified. (Gree is the largest AC manufacturer in China, but many of the internal components are manufactured in lower-cost countries. I'm not sure how good their quality control really is.)
As I understand it several years ago a popular Fujitsu refrigerant valve used inside other manufacturers' units had an unusually high failure rate, but the better-engineered repair part was alleged to be fine.
Dana,
Thanks for your comments. To clarify: I provided Julie advice for the best assumption to use when developing a replacement reserve account spreadsheet. That assumption does not necessarily indicate the predicted lifespan of the equipment under discussion. For a replacement reserve account, conservative assumptions are essential.