Savings resulting from turning down your water heater temperature are based on reducing standby losses (heat lost from water heater into surrounding area). Set too high, or at 140ºF, your water heater can waste anywhere from $36 to $61 annually in standby heat losses.
Though the DOE says you can save money on hot water by lowering the maximum temperature of your water heater from 140° F to 120° F, we don't necessarily recommend it. That's because the lower temperature might invite opportunistic bacteria—including Legionella, associated with Legionnaires' disease—to proliferate.
Common sense tells you the water heater doesn't use electricity when it's shut off so clearly you can save money. The energy experts say it's about $1.36 a day. The question you have to answer is whether it's worth it because there are some inherent problems with turning a water heater on and off.
It is cheaper to only put it on when needed. The reason for this is that the amount of electricity required to heat the water depends on how quickly the heat leaves the tank. Some will leave whenever you use the water, but some also leaves by getting out through the insulation.
The perfect temperature to set a water heater
If you're looking for a short answer, it's 120 degrees Fahrenheit (about 49 degrees Celsius).
The best temperature setting for a hot water heater is between 120 and 140 degrees. Below 120 degrees, bacteria can develop in the stagnant water sitting in the tank. Above 140 degrees, the water is so hot that you and your family members can be at risk for scalding in as little as two seconds.
Although it takes longer and requires more fuel to heat cold water, the energy required to maintain this constant temperature is much more expensive than the few times it is heated when necessary on occasion, due to its non-use, this water is also wasted, as a result, running a boiler continuously consumes more fuel ...
Turning your water heater off completely when it's not in use can help you save a small amount of money each month on your energy bills, but the hassle of manually turning your unit off and on typically outweighs the benefits.
However, if no one is home for a long stretch of time – like a typical 8-hour workday – you should turn the heat off, or set it to a low temperature, to save money, experts advise. The idea that it costs more to heat your home back up after the temperature drops isn't true, says the Department of Energy (DOE).
No, unless you're going on vacation for a month or longer, you shouldn't turn off your water heater. Here's why: You won't see significant energy savings. You'll create more problems by turning your water heater off/on repeatedly.
Sediment can build up over time in a water heater, shortening its lifespan. To prevent this, you should flush your water heater at least once per year. Flushing will help to remove any sediment that has built up and improve the efficiency of your water heater.
We recommend always keeping the heater set between 110 and 120 degrees. In the summer, try setting your water heater temperature at the low end of this scale, placing it close to or at 110 degrees.
Faulty fixtures or leaking connections and pipes can go unnoticed at the water heater because it is not an appliance you see every day. The leaks can become significant and result in an increase in the water usage bill and your energy usage bill.
According to most dermatologists, the ideal shower temperature is anywhere between 98°F (37°C) and 104°F (40°C)—and no more than 105 °F (41°C). Rinsing under lukewarm water allows you to stay comfortable and maintain your body temperature while reaping all the benefits of both hot and cold showers.
Savings resulting from turning down your water heater temperature are based on reducing standby losses (heat lost from water heater into surrounding area). Set too high, or at 140ºF, your water heater can waste anywhere from $36 to $61 annually in standby heat losses.
Generally speaking, a gas water heater should not be turned off unless you are leaving the house for an extended period of time. Even then the better choice for gas water heaters is to just turn the temperature down. In fact, many water heaters have a “vacation” setting on the temperature control.
Some estimates state that turning your water heater off at night could save you up to 10% on your monthly energy bills. If you have an electric water heater, and you're on an Economy 7 tariff, then it's usually more cost-effective for it to turn on for at least a couple of hours during the night.
It's better to leave the hot water heater on all the time, rather than turning it on and off. This is a very common energy saving myth. But in fact, you really don't need to be heating your water all the time.
Water Heater Temperature Recommendations
120 degrees Fahrenheit is the safety recommendation against scalding, but 140° is the common default setting.
It's generally much cheaper to heat water using your central heating system, rather than using electricity with an immersion. The exception might be during the summer, when you have your central heating turned off, or if you have an old inefficient boiler.
Reasons Your Water Heater Might Not Be Energy Efficient
There are two main issues why your water heater may be losing efficiency and doubling your cost to operate your system: an old system and sediment buildup.