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 FriedmanHome inspectors typically expect a generic water heater to last about ten years. However all of us have found 20 year old models still going strong, while on occasion a newer model 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.]

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

  • Corrosivity of the water supply - more corrosive water may shorten the water heater life or the life of its anode. We discuss various tests of drinking water, including water corrosivity,
    at WATER TESTS for CONTAMINANTS. In short, the chemistry of the water being heated affects the water heater life, and aggressive or corrosive water means shorter life for the water heater.
  • Mineral content in the water supply - if your water supply is high in minerals you may need a water softener
  • Water heater location - if the water heater is located where it is subject to flooding (as in our photo at above-left) the system is going to be damaged, short-lived, and possibly unsafe as well. Notice the multiple flood-lines on the water tank next to our client? Check out the shoes too. Don't wear white sneakers to inspect a crawl space.

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.

  • Water heater installation - improper installation of the water heater, or improper fuel or water piping connections or inadequate chimney venting on fossil-fuel fired water heaters can lead to safety problems or leaks and early heater failure.
  • Water heater maintenance - flushing mineral debris and dirt from a water heater can significantly extend its life as well as increase the quantity and temperature of domestic hot water the heater provides. If your water heater is making noises
    See WATER HEATER NOISE DIAGNOSIS, CURE since you probably need to de-scale the heater bottom.
    See WATER HEATER SCALE - De-Liming Procedure which are discussed at WATER HEATER NOISES.
  • Water heater anode replacement - the sacrificial anode protects a water heater tank from corrosion. Depending on the chemistry of your water supply, the anode may need to be replaced every few years or even more frequently. If suddenly your hot water (but not your cold water) smells like rotten eggs, the problem may be with a corroded sacrificial anode.
    see Check the Sacrificial Anode & Dip Tube of Your Water Heater Tank
  • Water heater tank type - most water heaters use a glass or porcelain liner which, along with the sacrificial anode, help protect the tank from corrosion. The construction of the water tank, methods and materials used affect the life of the tank, burner, and controls. Look at the water heater warranty period; a longer warranty probably means a more durable water heater tank.
  • Quantity of hot water used - using more hot water increases the duty cycle of the water heater and exposes the tank to extra risk of corrosion. The temperature to which the water heater is required to heat the hot water may also be a factor in tank or burner or other water heater part life. The quantity of hot water used, which determines how hard it works, is called the duty cycle or level of usage of the water heater (more use = shorter life).
  • Not enough hot water? If your water heater seems to be working ok but you just never have enough hot water,

  • Water heater warranty periods - the warranty for a given model water heater is also a predictor of how long the manufacturer expects the tank to last. (A grouchy friend opined to the author that all of the tanks are the same, but the water heater price is higher on a water tank with a longer warranty period. We have not found data to support this view.) We discuss water heater warranties in more detail just below.

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 FriedmanTypes 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. 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 are two key water heater maintenance articles.


Continue reading at WATER HEATER FLUSH PROCEDURE or select a topic from the More Reading links or topic ARTICLE INDEX shown below.



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WATER HEATER LIFE at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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