Equipment lifespan

How much longer will it last? AC, heat pump and gas furnace lifespan by age

Enter the type and its age, or the year it was built. The page works out, for the national stock of that type, how long the ones that reached that age went on: when half of them were out of use, and what share were still in use five years later. It is read off a published survival curve, with the study's own conditions beside it, and it is not a forecast for your unit. The study, and what it says it assumes, are in the source receipt below.

The study's median life, by type

The age at which half of the national stock of each type was out of use, on the curve fitted in the study. The figure for a unit that has already reached a given age is the one the calculator above works out.

Central air conditioner18.0 years (Table 2)

Heat pump14.6 years (Table 3)

Gas furnace22.6 years (Table 4)

01Source
receipt

Where these survival figures come from, and what the study assumes

This page reports how long equipment of a type went on from a given age in the national stock, read off a survival curve that one study fitted to national survey data. It is a statement about a population, not a prediction about the unit in front of you, and the study's own conditions are printed here beside its figures rather than under them.

The study: Lutz, Hopkins, Letschert, Franco and Sturges, "Using National Survey Data to Estimate Lifetimes of Residential Appliances", Lawrence Berkeley National Laboratory, October 2011 (OSTI 1182737, md5 315c4d3b0b6d2cb3be93330a4c6131ab). It fits a survival curve to the national stock of each type by age, from the surveys it names on its first page: RECS 1990, 1993, 1997, 2001, 2005 and AHS 1991, 1993, 1995, 1997, 1999, 2001, 2003, 2005, 2007.
What the study says it assumes: The study's summary says the analysis rests on several important assumptions and names two, which are the two quoted here, in its words and not a paraphrase. "The first is that a Weibull distribution is the correct distribution to use for appliance lifetimes." "The second assumption is that consumer behavior and appliance lifetimes have not changed through time." Its method section sets out more assumptions than its summary names, and only these two are held here.
Where the curve runs out: The oldest age group the survey bounds is "Over 20 years" (its Table 1, printed for central air conditioners), so past 20 years every unit falls in one open range and a figure there rests on the shape of the fitted curve rather than on a counted bucket. The line on this page says so when it reads there. The heat-pump curve carries a further restriction of its own: the input data was restricted to AHS and RECS only from 2001 to 2007 (the most recent data available). The furnace curve is for gas furnaces.
The median life of each type, on the study's curves: Half of central air conditioners were out of use by 18.0 years, half of heat pumps by 14.6 years and half of gas furnaces by 22.6 years, rounded to one decimal as this page does elsewhere. The study attaches a condition to the air-conditioner figure: "it was assumed that 95% of the appliance stock is in residential units and, thus, is captured by RECS and AHS. If it was assumed that 100% of the stock was in residential applications, the median lifetime would decrease to 16.5 years; if it was assumed that 90% of the stock is in housing units, the median lifetime would increase to 19.7 years." And to the heat-pump figure: "No single realistic survival function easily fits the shipment and stock history for residential heat pumps."

The study, its conditions and its assumptions are LOOKED UP and quoted as printed. The figures this page reports for an age you give are COMPUTED from the study's fitted curve, over ages 1 to 60 years, rather than read off a survey count. A survival curve answers how a population behaved, so it cannot say when one machine will stop: it knows nothing about how this unit was installed, how it was maintained, or what it has been asked to do. Read against a unit's decoded age it says where that unit sits among others of its type, and that is the whole of what it says.

Questions

How long do AC units last?

There is no one life for one unit. In the national stock, on the survival curve Lawrence Berkeley National Laboratory published in October 2011, half of all central air conditioners were out of use by 18.0 years, and the study attaches a condition to that figure: "it was assumed that 95% of the appliance stock is in residential units and, thus, is captured by RECS and AHS. If it was assumed that 100% of the stock was in residential applications, the median lifetime would decrease to 16.5 years; if it was assumed that 90% of the stock is in housing units, the median lifetime would increase to 19.7 years." For how long the ones that reached a given age went on, enter the age on this page.

How long do heat pumps and furnaces last?

On the same study's curves, half of all heat pumps were out of use by 14.6 years and half of all gas furnaces by 22.6 years. For heat pumps the study says: "No single realistic survival function easily fits the shipment and stock history for residential heat pumps." and the input data was restricted to AHS and RECS only from 2001 to 2007 (the most recent data available). Its furnace curve is for gas furnaces only.

Should I replace my old AC?

This page does not say. It gives how long that type of equipment lasted from a given age across the national stock, which is a population figure and not a forecast for any one unit. Repair or replace is not worked out here.

Why does this page not show one number in its title?

Because the figure that matters depends on the age. Of the air conditioners that reached a given age, how long half of them went on is a figure that changes with the age, and this page works it out for the age you enter.

Read the build year from the serial AC not blowing cold air? The check