QUESTION: I've heard I can save money by lowering the temperature on my hot water tank. Is this really effective?
ANSWER: Your water heater uses more energy than any other appliance in the home, except your heating system. Depending on fuel source and rates, water heating typically costs a family of four between $280 and $310 a year. It makes sense to look at how you can reduce your utility bill with your present hot water heater. The more water you want to heat, and the hotter you want it, the more energy you will need.
No matter what type of water heater, there are two ways to reduce the operating cost: lower the temperature of the water heater or use less water. According to the American Council for an Energy-Efficiency Economy, each 10-degree Fahrenheit reduction in water temperature will generally save 3% to 5% on your water-heating costs.
Washington now requires that all new water heaters be set at 120-degrees Fahrenheit at the time of sale. This increases the safety and energy efficiency of the water heater. If your water heater was purchased before 1984, it's likely the thermostat is set higher than 120 degrees, probably between 140 and 150 degrees. Most people shower at a temperature of 105, so a setting of 120 will require mixing with cold water for a comfortable temperature.
Water temperatures greater than 120 are generally not necessary and should be reduced for several reasons:
It can cause scalding: Children and seniors are most often scalded. Scalding occurs in two seconds at 150 degrees, 15 seconds at 140, 30 seconds at 130 and 10 minutes at 120.
It increases the rate of corrosion on internal fitting and other surfaces.
It causes the water heater to lose heat at a much greater rate than would occur if the temperature was kept lower.
A 120-degree setting is about midway between the "low" and "medium" settings on most gas water heaters. Electric water heaters often have two thermostats (with numerical marking), one for the upper heating element and one for the lower heating element. These should be adjusted to the same temperature to prevent one element from doing all the work and wearing out prematurely. Be sure to turn off the electricity at the circuit breaker before removing access panels on an electric water heater.
If you have an old water heater and it's located in an unheated space, it's important to insulate it because water heaters can quickly lose heat through their shell. Older water heaters only have an inch or two of fiberglass insulation (R--5). They should be wrapped with additional fiberglass insulation blankets, which can be purchased at home supply and hardware stores.
Gas water heaters must be wrapped in such a way that the insulation doesn't block the air intake, so the insulation will not come into contact with the flue. This is essential for proper functioning of the heater and to avoid a fire hazard.
You can also reduce your demand for hot water through one or more of the following actions. Simply changing a few habits can have immediate results.
--Using the warm wash/cold rinse setting on your washing machine can save about 65% of the energy you would use with a hot wash/warm rinse.
--Adding low-flow faucet aerators to existing fixtures. Older shower heads use 5 to 8 gallons of water per minute, while low-flow shower heads use 2.5 gallons per minute.
--Running your dishwasher only with a full load.
--Fixing that leaky hot water faucet that is wasting both water and energy.
Produced by the Energy Extension Service, a division of the Washington State Energy Office.