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furnace and water heater

A water heater heats water, so occupants can wash in warm or hot water. In some cases the heated water is used to heat the home with water or steam radiators. How water piping can also be wisely placed to provide other benefits, like heating a bathroom's tile floor.



If a hot water heater is not used for several weeks, hydrogen can build up in the tank. This can be dangerous, if an electrical appliance is the first device to use the water heater. To avoid a possible explosion, if you haven't used the hot water heater for two or more weeks, run the hot water from the tap for a few minutes before using an appliance, like a clothes washer or dishwasher.

Energy usage and efficiency[]

New, higher efficiency furnaces and water heaters create a higher acidic exhaust, which can corrode older chimneys, especially a brick one without a liner. So, if you are replacing an older system, you may need a new chimney vent or liner for your chimney.

By using a temperature setting that's lower than the maximum that most systems allow, you can reduce the chance that someone one will accidentally be scalded. This is especially true in a house with small children, where a little one may decide to do something like take a bath on his or her own... stepping into the tub and then turning on the hot water. Many home water heaters go up to 140 degrees Fahrenheit (°F), and for most purposes 120° F (about 49° Celsius) is hot enough. The exception is some older dishwashers which do not have their own water heating. (Check your appliances' manuals.)

As a bonus, if you turn down your water temperature, you save energy and money. For that 20°F reduction in temperature, it's likely that you'll save 6-10% on the energy to heat your water. And in addition, at the lower temperature the corrosion and mineral build up in the pipes will occur more slowly and other components in your system may last longer.

If you want to save on energy costs and use a "greener" energy source, consider a solar powered water heater.

See the article on solar water heaters on the Green wikia.

hot water tanks


In the U.S., the capacity of the water heater is generally 30 gallons for a mobile home, 40 gallons for a home with 1-2 bathrooms, and 50 gallons for homes with more bathrooms. You save energy by not getting a larger capacity than you need.


I've been told that water heaters break down and need replacement without much warning. Is that your experience? With an older water heater (more than 20 years old), should I be ready to replace it without notice?

  • Surprise! The answer was "yes", in my case.

What are some common things to look for that tell me it is time to replace my water heater?

  • Water leak from the tank or around its base
  • A Rotten egg smell (sulfur)
  • Weird noises - hissing, popping, sizzling or high pitched whining
  • Not enough or no hot water 
  • Rust colored water
  • Rust stains on the underside of the heater
  • Erratic heating
  • Slow "recovery" (time to heat water once it's run out)

What are some common causes of water heater failure?

  • No water in the tank caused the electric heating element to burn up
  • Burner or heating element fails.
  • Thermostat breaks.
  • Valve sticks.
  • Heating elements that are corroded
  • bacterial infection inside of the tank
  • faulty pressure relief valves
  • a rusted, leaking tank
  • Faulty gas pilot
  • Faulty gas thermocouple
  • Faulty gas pilot control valve
  • Excessive sediment has built up in the bottom of the tank
  • Unit is undersized for water heating demands
  • Broken or damaged dip tube
  • Bad plumbing installation
  • Crossed cold and hot water connections
  • Gas supply or control problems
  • The pilot light (on gas heater) is out
  • Sacrificial anode rod is failing
  • A tripped circuit breaker if it is an electric water heater

When to replace? General advice seems to be that a water heater which is malfunctioning should be replaced if it's over 8-10 years old. (Not surprising, sellers of hot water heaters tend to recommend the shorter timeframes.) Some people replace their water heaters at 12-15 years even if it's not showing signs of failure. Because newer water heaters can be much more energy efficient (due to newer designs), this can be cost effective. This will depend on how much hot water you use, the cost of your gas or electricity and the efficiency of your older heater. Newer heaters with a minor malfunction (e.g., the thermostat) may be repaired much more cheaply than installing a new one. Should I "flush" the hot water heater, and if so, how often?

  •  ?


On other Wikia

See the article on solar water heaters on the Green wikia.



The following are commercial sites listed with the newest added at the top.