Water heater replacement

A water heater requires replacement only when the tank is leaking. If there are problems with any of the controls, they can be replaced individually as needed. You cannot tell by looking at a unit when it will start leaking. The projected life for an oil- or gas-fired water heater is from seven to ten years, although units have been known to last over fifteen years. Electrical units have a longer projected life than oil- and gas-fired heaters. This is because the electrical heating element is immersed in the water, imparting its heat directly to the water and not to the tank, whereas in an oil- or gas-fired heater the flame imparts its heat directly to the base of the tank. The intense heat results in expansion and contraction stresses that effectively shorten the life of the tank. Look at the temperature control knob (thermostat) on the tank. If it is at the maximum setting, the unit has been operating at a high temperature, and a shorter life span should be anticipated.

The age of a tank water heater can generally be determined from the serial number found on the tank’s data plate. The numbering system, however, varies by manufacturer. For example, for Rheem or Rudd water heaters, the first four numbers of the serial number indicate the month and year of production (thus 0286 would indicate that the heater was manufactured in February 1986). Usually a water heater is installed within several months of its manufacture.

With an A. O. Smith water heater, the date can also be found by checking the serial number. For example, in serial number 800-A-8412345, the letter stands for the month of manufacture (January in this case); and the middle number (84) stands for the year of manufacture, 1984. The letter code for month of manufacture is:

A-January G-July

B-February H-August

C-March J-September

D-April K-October

E-May L-November

F-June M-December

If you determine that the water heater is over ten years old, you should not anticipate an extended life for the unit, even though it might look relatively new (shiny and clean on the outside).

I have been asked by clients whether it is necessary to replace a gas-fired water heater that has been in a flooded basement. It is not necessary to replace the unit. The tank is designed to hold water and therefore cannot be damaged by it. However, the burner assembly and controls (pilot, thermocouple, and thermostat) can be damaged and should be checked by a competent serviceman. If any of the controls are malfunctioning, they should be replaced as needed. Also, when the insulation between the tank and the jacket gets wet to the extent that it becomes thoroughly soaked, it can sag and be less effective as an insulator. If this should occur, you will feel “hot spots” on the jacket. This condition can easily be remedied. Insulation jackets are available that fit over water heaters to reduce heat loss.

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