A Debate Steeped in Hot Water
Do lower water-heating temperatures mean lower energy bills and safer delivery?
True or false: 120°F is a safe hot-water storage and/or delivery temperature?
Although manufacturers, industry agencies, and the media have lulled us into believing that turning down a water heater’s thermostat will save energy, let’s take a closer look at the facts.
For starters, a 120°F is not a safe delivery temperature. At 120°F, it takes only 80 seconds for a child to suffer a second degree burn and 3.1 minutes for a third degree burn; infants and the elderly can suffer second and third degree burns even more rapidly.
According to the American Hospital Association, more than 100,000 cases of scalding from hot water occur every year. The National Safe Kids Campaign indicates that more than 26,000 of these cases involve children and that an average of nine children die from scalding-related injuries yearly.
Unless your water heater is more than 20 years old, its thermostat was set at the factory for an average storage temperature of 120°F. However, these thermostats, while reliable devices that typically outlast the water heater itself, are not precise instruments. Additionally, settings that target 120°F often are not stable because thermostats allow stored water to cool by as much as 15°F before cycling to reheat. Checking your water heater’s delivery temperature at any given point of use yields a range of temperatures based on when the water heater last actively heated water.
There was a time when water heaters came set to store water at 140°F and dishwashers did not have internal heaters for a sanitizing rinse. It was widely recognized then that 140°F water was hot enough to kill bacteria. But scaldings led to lawsuits and a desire to increase energy efficiency caused manufacturers to remove temperature markings from thermostat dials. Most now read “vacation, warm, or hot.” With the storage temperature lowered to…