Staying out of Hot Water

The temperature setting of your water heater is an important, yet often overlooked setting. This is why an Atlantic House Whisperer inspector pays special attention to this along with thousands of other items during your home inspection.

The recommended temperature for a water heater is 120 deg F and does not always correspond to what the thermostat on the heater says but should be tested by using a thermometerĀ  at the closest faucet to the water heater to check the actual temperature of the water coming out of the faucet.

120 deg F is recommended for several reasons, the first of which is that it extends the life of the water heater. Or being put another way, a 20 deg increase in water temperature can reduce the life span of the heater by 40%.

Energy requirements also increase with temperature increases. The amount of energy required to heat the water depends on the difference in the water temperature coming into the heater and the water coming out of the heater. The larger the difference, the more energy that is required to maintain that difference. It also helps to have an insulating wrap around the heater to help preserve the heat.

While it’s good to preserve the water heater and to save energy, one of the most important reasons is safety. The chart below gives an idea of how quick burns can result from hot water. An adult has an approximate skin thickness of 2.5mm and the chart below is based on adults, but a child 5 and under has a skin thickness of about .56mm.

For a child 5 and under, it only takesĀ 25% or less time to cause third degree burns thanĀ  indicated in this chart.

Temperature Time to produce Third Degree burns
120 deg F 5 minutes
125 deg F 1-1/2 to 2 minutes
130 deg F About 30 Seconds
135 deg F About 10 Seconds
140 deg F Less than 5 Seconds
145 deg F Less than 3 Seconds
150 deg F About 1-1/2 Seconds
155 deg F About 1 Second
160 deg F Instantaneously

According to the National Safe Kids Campaign, 4,000 to 5,000 children are scalded each year, most while bathing. Continuous supervision of young children is the most important factor in preventing tap-water scald burns.

One way to help prevent burns from hot water is by using anti-scald fixtures which actually have internal mixing valves that mix cold water with the hot to prevent water above the set point from exiting the fixture.

Dishwashers need hot water to sterilize the dishes and this is why they have their own heating element to heat the water. Most of the laundry detergent today does just fine in warm, and even cool water.

Most water heaters come preset close to 120deg F and if you haven’t adjusted it, should be close, but it’s better to check the temp at the faucet to be sure.

To adjust the temperature setting of a water heater, it should be done in small increments giving at least 12 hours to stabilize. When setting a gas heater there is just one setting and pretty cut and dry. An electric water heater is a bit different as they have 2 heating elements.

An electric water heater has an upper element and a lower element. The cold water enters the top of the tank and is piped to the bottom through a dip tube. The hot water exits the tank from the top. The top heating element has priority over the bottom element and is the first to turn on when heating the water. Once the top thermostat is satisfied, the bottom element will turn on until it is satisfied. The top element is what sets the final temperature of the water leaving the tank and the bottom element is basically a preheat element and can be set at a slightly lower temperature than the upper thermostat.

Some water heaters, sometimes known as Apollo Systems, are also used to provide the heat source for the house by sending hot water to a coil in the air handler or furnace, radiators or underfloor heating. These water heaters will be set higher to provide adequate heat for the home, but should be installed with a master thermostatic mixing valve that limits the water temperature to the plumbing fixtures.

The temperature setting of your water heater has an affect on the life of the tank, the energy required to operate the heater but most importantly the safety of friends and family that will be using the water. We hope that this has given home owners a better understanding of just one of the thousands of things Atlantic House Whisperer check during your home inspection.

If you have any questions or comments, please feel free to contact us or just leave a comment at the bottom.


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