The facility should insure that plumbing fixtures that supply hot water and are accessible to the residents shall be thermostatically controlled so the water temperature at the fixture does not exceed one hundred twenty degrees Fahrenheit (120°F) (49°C). The water should be at a temperature range of one hundred five degrees Fahrenheit to one hundred twenty degrees Fahrenheit (105°F–120°F) (41°C–49°C).
HOW OFTEN SHOULD YOU CHECK? This is done at least weekly or more often if needed. If you are having some readings where the temps are out of range, especially over 120 degrees, you need to check them as often as necessary. There have been circumstances that required that they be checked every hour for a day or so. There have been others that have had to do them daily for a couple of weeks to make sure that the temperatures stay within the range.
HOW MANY SAMPLES SHOULD WE CHECK? This depends on the size of your facility, the number of hot water heaters and the variance in temperature from one room to the next. Normally, you would do a couple for each hot water heater with one being at the beginning of the hot water circuit and the other toward the end. The circulating pumps should keep the temperatures from varying too much from room to room. If you find that the temperatures do vary greatly, you may consider testing other faucets on that hot water line.
WHAT TIME OF DAY SHOULD WE CHECK? The time of day that the water tests are made should alternate from week to week. The reason for doing this is to make sure that water usage doesn’t impact the water temperatures. The water heaters should have the capacity to maintain the same temperature at all points of the day, but if it doesn’t your alternating schedule will determine this.
HOW IS A THERMOMETER CALIBRATED? It is important to make sure that the thermometer is giving you an accurate temp.
There are two ways to check the accuracy of a food thermometer. One method uses ice water, the other uses boiling water. Many food thermometers have a calibration nut under the dial that can be adjusted. Check the package for instructions.
Calibration of a thermometer in ice water – To use the ice water method, fill a large glass with finely crushed ice. Add clean tap water to the top of the ice and stir well. Immerse the food thermometer stem a minimum of 2 inches into the mixture, touching neither the sides nor the bottom of the glass. Wait a minimum of 30 seconds before adjusting. (For ease in handling, the stem of the food thermometer can be placed through the clip section of the stem sheath and, holding the sheath horizontally, lowered into the water.) Without removing the stem from the ice, hold the adjusting nut under the head of the thermometer with a suitable tool and turn the head so the pointer reads 32 °F.
Calibration of thermometer using boiling water – To use the boiling water method, bring a pot of clean tap water to a full rolling boil. Immerse the stem of a food thermometer in boiling water a minimum of 2 inches and wait at least 30 seconds. (For ease in handling, the stem of the food thermometer can be placed through the clip section of the stem sheath and, holding the sheath horizontally, lowered into the boiling water.) Without removing the stem from the pan, hold the adjusting nut under the head of the food thermometer with a suitable tool and turn the head so the thermometer reads 212 °F.
Even if the food thermometer cannot be calibrated (i.e. digital display), it should still be checked for accuracy using either method.