Flooded Water Heater (C) Daniel Friedman Life Expectancy of Water Heaters
Average water cylinder life, factors that affect water heater life

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Life expectancy of a water heater or cylinder:

This article describes the typical service life of a residential water heater - answering the question: how long will my water heater last?

We give typical water heater life expectancies, we list some of the factors that affect water heater life, we recommend maintenance steps to get the longest useful life of your water heater, and we discuss the relationship between water heater warranties and the actual life expectancy of the heater.

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How Long will My Water Heater Last? What Determines Water Heater Life?

Flooded Water Heater (C) Daniel FriedmanA typical gas or oil fired water heater life expectancy is from 8-12 years according to sources we've researched (and report here), and for tankless water heaters, 18-20 years.

Home inspectors typically expect a generic water heater to last about ten years. However inspectors, plumbers, and homeowners have found 20 year old water heater or geyser models still going strong, while on occasion a newer model water heater (synonyms calorifier, cylinder) fails early.

The chronological age of a water heater (how long ago was it made) is hardly the only factor that determines how long the water heater will last. Our photo at left illustrates an antique gas-fired water heater installed in the Gaudi apartments in Barcelona, Spain. [Click to enlarge any image.]

Factors Affecting the Life of a Water Heater or Geyser

Here are some other factors that affect the life of a water heater:

Water heater in a crawl space pit (C) Daniel FriedmanOur next photo (left) shows how a tall water heater was shoe-horned into a low crawl space by digging out a pit to allow the tank to stand upright. This heater is also likely to be exposed to flooding.

We have also seen water heaters placed horizontally to fit into a tight crawl space - a possibly dangerous installation. Unless the manufacturer has specifically designed a water heater to mount horizontally there is risk that the tank or other components will not be properly supported and the system will be damaged and unsafe.

In sum, improper location or improper position of a water heater, such as mounting some water heaters horizontally or locating a water heater in a flood prone location or where it can't be properly serviced or vented can lead to early failure of the heater as well as voiding the manufacturer's warranty.

Also see WATER HEATER LIFE EXPECTANCY COMPARISONS for a short list of other factors that determine the life expectancy of a water heater.

What are the Typical Terms of Water Heater Warranties

Flooded water heater voids warranty (C) Daniel Friedman Types of water heater tank and water heater warranty - modern "glass lined" water tanks are coated to resist corrosion. The manufacturer's warranty period as well as a description of what is covered under the warranty are clues both to the importance of water heater maintenance and hints about how long the company expects their water heater tank to last.

Typical water heater warranty periods for a water heater installed for use by a single family are 6-years, 9-years, or 12-years.

Tankless water heaters have a typical life expectancy of more than 20 years.

The warranty period of a water heater may be encoded in its model or serial number.

For example Lochnivar water heaters include a model number prefix that determines whether the heater is warranted for six years or for ten years. If the water heater is in any other use than one-family residential, the heater is warranted for one-year on parts and three years on the tank itself.

Watch out: if the water heater tank leaks and fails before the end of the warranty period, if the system has not been properly installed or maintained the warranty may be void. Water heater warranties typically indicate that the tank is warranted against leaks due to rust, corrosion, or chemical action of the water but the warranty will exclude a tank failure due to scale.

Our photograph above shows a water heater installed in an area subject to recurrent flooding.

This heater will have a short life, may be dangerous (risk of explosion from a combination of pressure, rust, and flooding), and is almost certainly not going to be warranted by the maufacturer if they see how it was installed.

Watch out: as well to perform the manufacturer's recommended water heater maintenance chores. Flushing a water heater on schedule, checking and replacing the water heater anode when required, and attention to the water quality in the home - corrosivity and mineral level for example, can make a significant difference in the water heater's life.

Also see WATER HEATER LIFE EXPECTANCY COMPARISONS for a comparison of the typical life expectancy of different types of water heaters or methods of producing domestic hot water.

Just below at "Continue reading" are key water heater maintenance articles that can significantly extend water heater life.

Research on Water Heater Life Expectancy

Water heater installed base by age, US DOE 2010 at InspectApedia.comIndirectly we can infer some interesting information about actual water heater life for the United States from the U.S. DOE Energy star report cited below.

[Click to enlarge any image]

This graph, excerpted from that document shows us that in 2010,

Interpreting this data to make a statement about water heater life, we have made up the table below:

Table of U.S. Water Heater Actual Life by Fuel Type in 2010

Water Heater
Energy Source
Age of

of Total
by Energy

Gas-Fired >20 years 3 6 %
Gas-Fired 7-20 years 26 48 %

0-6 years

25 46 %
Electric >20 years 2 5 %
Electric 7-20 years 20 47.5 %

0-6 years

20 47.5 %
Oil-Fired (no data in the DOE report)      

Source: 2010 WATER HEATER MARKET PROFILE [PDF] (2010) U.S. Department of Energy, includes only gas and electric water heaters

Other water heating energy sources such as wood and solar water heating are not included in this data.

Oil fired water heaters are used in the U.S. primarily in the northeast. Still 42% of water heaters are gas in New England and 58% of water heaters are gas-fired in the Middle Atlantic states. Much lower percentages of water heaters are gas-fired in the East-South-Central and South Atlantic US.

This table assumes that water heaters are principally installed because a prior heater has reached the end of its life. This assumption is inaccurate insofar as it does not reflect the installation of water heaters as the first heater installed, such as in a newly-constructed home.

For example, in December 2017 there were 1192thousand housing starts compared with 41,820 thousand housing starts in the UK and 217 thousand housing starts in Canada. - source: Trading Economics, retrieved 2018/02/05, original source



Continue reading at WATER HEATER FLUSH PROCEDURE or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.



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