Last week one of my readers sent me a question asking what temperature a home water heater should be set at. I recommended setting it between 120 to 130F.
If it was easy to set the water heater at just the right temperature, 130 F would be my target. Maybe I should have recommended 125 to 135 for a target range. I give a ten-degree range because setting the water heater temperature requires some trial and error.
Any temperature less than 120 is too low for health reasons. Any temperature above 140 is wastefully high if you want to save money on your energy bills.
Check it with a meat thermometer
Don’t trust the markings on the dial or adjustment screws on the heater. I suggest that you check it with meat thermometer. The kind of thermometer that you stick into the meat while it is roasting has just the right temperature range for the job.
Put your meat thermometer in a coffee mug or bowl. Set this test station in your kitchen sink. Let the hot water run into the coffee mug until the temperature reading stops going up.
If reads 140 for rare beef or higher the water is hotter than you need. Make an adjustment on your water heater and check it again the next day. Work the temperature down with small adjustments until it is in the right range.
Once you find the right setting, I suggest you get your magic marker out and mark it so you can find it again quickly. Some day you may have a little helper around who like to twist knobs.
Reducing the temperature saves you money
Heating the water at too high of a temperature wastes money on your energy bill. The higher the temperature the more energy is needed to heat the incoming cold water up to the point where the heater shuts off.
While the heated water sits in the tank, it cools off. More energy is needed to keep the water at the set temperature. This cooling and re-heating goes on 24 hours a day whether you use any hot water or not.
Tank less or “on demand” water heaters, avoid some of the energy waste by eliminating the storage of hot water. But, setting them at too high of a temperature will cost you extra on your energy bill.
New water heaters are usually set at 140 degrees. When folks sell a water heater, they want the customer to get really hot water right from the start. If you have never reset your heater temperature, it is likely to be wasting your money.
There is conflicting information available from our government. The OSHA folks say that workers need to be protected if they are exposed to temperatures of 140 F or above. The U S Health Department wants public use hot water 140 F or higher to kill the bacteria quickly. The U S Department of energy suggests a 115 to 120 F setting residential water heaters to save energy.
My target recommendation of 130 is a level that provides good bacteria control and realistic energy savings.
A while back, I wrote an article titled; Energy Savings and Healthy Hot Water that you should read.
If you need a new meat thermometer here is a good source for one. I even added this to my Amazon wish list.