Once you know how old a unit is, the next question is usually how long it has left. Nobody can answer that for a single unit: service life depends on water quality, installation, maintenance and use. What can be stated is what U.S. government programs publish as typical figures. This page uses only ENERGY STAR, the EPA program for energy-efficient products, and says for each figure what kind of number it is.
| Equipment | Years | What the figure is |
|---|---|---|
| Tankless (on-demand) gas water heater | 20 | Life expectancy. ENERGY STAR gives a life expectancy of 20 years for tankless water heaters. |
| Heat pump water heater | 13 | Assumption in a savings calculation. ENERGY STAR's savings estimate for heat pump water heaters assumes a 13-year lifespan. It is an assumption of the calculation, not a measured service life. |
| Central air conditioner or heat pump | 10 | Age at which to consider replacement. ENERGY STAR suggests considering replacement when a heat pump or air conditioner is more than 10 years old. |
| Furnace or boiler | 15 | Age at which to consider replacement. ENERGY STAR suggests considering replacement when a furnace or boiler is more than 15 years old. |
A life expectancy, such as the 20 years ENERGY STAR gives for tankless water heaters, describes how long such units typically last. A replacement threshold, such as 10 years for air conditioners and heat pumps or 15 years for furnaces and boilers, is the age at which ENERGY STAR suggests weighing a replacement; it is not a prediction that the unit will fail. The 13 years used in ENERGY STAR's savings estimate for heat pump water heaters is an assumption of that calculation and nothing more.
The U.S. Department of Energy's Energy Saver pages used to give ranges for tank water heaters, tankless heaters and heat pump water heaters. On October 27, 2026 those pages returned "page not found", so we do not quote them. If they come back at a new address, we will add them with that address and the date we read them. We also do not show a separate service life for air source heat pumps, because we found no government figure for it beyond the ENERGY STAR threshold.
Not because of its age alone. ENERGY STAR suggests considering replacement after 15 years, which means comparing the cost of keeping it with the cost and savings of a new one. A furnace that is safe and works well can keep running; a licensed technician can tell you its condition.
The U.S. Department of Energy pages that gave a range for tank water heaters returned "page not found" when we checked them on October 27, 2026. We do not quote a figure we cannot link to a working primary source.
It is the earliest possible start. Installation can come months later, so if you know the installation date, count from that for wear and use the manufacture date for warranty questions.
ENERGY STAR pages, checked on the date shown. Service-life figures are re-checked at least once a year.
Page updated . Decoding rules last checked against their sources on the date shown with each source.