Calibrating the rain gauge on your AcuRite Iris (5-in-1) Weather Sensor ensures accurate rainfall measurements. Here's how to do it: First, make sure the sensor is perfectly level using the built-in bubble level. Next, use a compatible companion unit or AcuRite software to monitor rainfall during calibration. Prepare a calibration cup by making a small pinhole in the bottom of a plastic cup. Hold the cup over the rain gauge and slowly fill it with exactly 1 cup (8oz) of water, allowing it to drip into the gauge. You should hear the internal buckets tip, and water should drain through the sensor. Your companion unit should display rainfall in approximately 0.01" increments after each bucket tip. The cup should take at least 20 minutes to empty to simulate a normal rainfall; a faster emptying time may lead to inaccurate calibration. Once the cup is empty, your companion unit should read approximately 1.06". For optimal results, ensure a consistent drip rate where approximately an equal number of water drops (around 25) fall between each bucket tip. If this isn't the case, you may need to adjust the calibration screws located on the bottom of the AcuRite Iris sensor to balance the tipping of the buckets. To adjust the rainfall reading, make equal adjustments to both calibration screws. Turning the screws clockwise will increase the rainfall reading, and turning them counterclockwise will decrease it. For example, to adjust the rainfall reading by 2%, turn both screws 1/8 of a turn. For a 4% adjustment, turn them 1/4 of a turn, and for an 8% adjustment, turn them 1/2 of a turn. Always consult your AcuRite Iris (5-in-1) Weather Sensor instruction manual for more detailed illustrations and guidance on rain gauge calibration.
