A thermometer may lose accuracy after years of use or after a particularly hard jolt. First, you need a container of water at a known temperature – the closer to the mid-range the better. A fever thermometer is ideal for measuring the temperature of the water.

Making an Ice Slurry

  1. Fill a 1 cup measuring container with a slurry of ice water using 3 parts crushed ice to 1 part water.
    Note: It is very difficult to get a 32°F/0°C ice water temperature. It will probably be closer to 34°F/1°C.
  2. Allow to stand for 3-5 minutes.

Using an Ice Slurry

  1. Immerse the stem into the middle of the ice slurry to a depth of at least 3 inches. Do not let the stem touch the bottom of container.
  2. Hold the dial firmly (pliers or a wrench may have to be used) and slowly rotate the hex nut beneath the dial. Use the pliers or wrench to adjust the next nut. The pointer will start to move.
  3. Rotate the nut clockwise to increase the reading. Rotate the nut counter clockwise to decrease the reading.
  4. Stop adjusting when the pointer indicates the temperature of the water.

Using Boiling Water

Boiling water (adjust for altitude above 1,000 feet*) can be used to recalibrate your thermometer. Please be cautious around boiling water.

  1. Immerse the thermometer stem in the water to a depth of at least 3 inches. Do not let the stem touch the bottom of container.
  2. Hold the dial firmly (pliers or a wrench may have to be used) and slowly rotate the hex nut beneath the dial. Use the pliers or wrench to adjust the hex nut. The pointer will start to move.
  3. Rotate the nut clockwise to increase the reading. Rotate the nut counter clockwise to decrease the reading.
  4. Stop adjusting when the pointer indicates 212°F/100°C.

*Note: For every 500 feet of elevation, reduce the expected boiling point of water by 0.5°F/0.25°C.

Using the Calibration Tool on Sheath

Models IRT220, IRT550, IRXL220, IRXL400, IRT220-F, IRB220-F, IRB220-F-6.5 and IRTL220-F

  1. Seat the hex nut on the thermometer into the head or wrench of the sheath, depending on sheath style.
  2. Immerse the stem into the middle of the ice slurry or boiling water (212°F/100°C at sea level) to a depth of at least 3 inches.
  3. Rotate the nut clockwise to increase the reading. Rotate the nut counter clockwise to decrease the reading.
  4. Stop adjusting when the pointer indicates the temperature of the water.

Calibrating Digital Thermometers

Models DTT450, DTQ450X, Q2-450X, DTW450, DTW450L

  1. Immerse the stem into the middle of the ice slurry to a depth of at least 2 inches. Do not let the stem touch the bottom of container.
  2. Press the CAL button for 2 seconds. The display will be blank for 2 seconds.
  3. Release the CAL button and 32.0°F/0°C appears.

Note: To avoid accidental recalibration, this function only works when the water temperature is 30 to 34°F/-1 to +1°C. ERR will appear for 2 seconds if the water is not within this range and then return to the temperature display mode.