Do You Know the Best Temperature for Your Water Heater?
The best temperature for your water heater strikes a balance between household comfort, efficiency and safety. The settings on the thermostats of many hot water heaters can increase water temperature up to 140 degrees or even higher. Using the “high” setting or cranking the knob as far as it will go is a bad idea for several reasons:
- 140-degree water causes severe scalding in just five seconds.
- Higher settings mean longer burner “on” cycles to raise cold municipal water to that temperature, resulting in higher water heating costs.
- Because heat exchange occurs at a higher rate the hotter the water in the tank is, standby heat loss from the heater occurs more rapidly as water temperatures rise above 120 degrees—another factor in reduced efficiency and increased operating costs.
Setting the Best Temperature for Your Water Heater
On most water heaters, the center notch in the thermostat dial represents the 120-degree recommended temperature. However, since dial markings may be inaccurate, it’s a better idea to actually measure the hot water temperature with a thermometer at a household tap located far from the heater. Mark the first temperature you measure on the thermostat dial, then incrementally turn the dial down, rechecking the temperature two hours after each adjustment until you verify 120 degrees.
Make a bold mark to indicate that setting on the dial. Water heater temperatures above 120 degrees are sometimes justified to prevent harmful bacteria formation in the tank. These are usually instances where someone in the household has health issues that might lower immunity to these microorganisms. In such cases, the tank thermostat may be set as high as 140 degrees to effectively kill bacteria. However, an anti-scald mixing valve should be installed in the water supply line immediately downstream from the water heater to ensure that household tap water is a safe 120 degrees.
For more information on setting the best temperature for your water heater, contact Sobieski Services. Our goal is to help educate our customers in Delaware, Pennsylvania, Maryland and New Jersey about energy and home comfort issues (specific to HVAC & plumbing systems).
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