How to Calibrate a Bunn Coffee Machine
When a Bunn coffee maker becomes uncalibrated, it can cause a series of unwanted problems, such as under-brewed, too strong or watered-down coffee. Calibrating your machine’s flow rate before brewing is essential to maintaining the quality of the pot and consistent flavor between batches. If you think your coffee is tasting a little funny or if you need to replace the thermistor, CPU or CBA, then learn how to calibrate a Bunn coffee machine in 6 easy-to-follow steps.
In this section, you’ll learn how to calibrate the flow rate and temperature probes on your AXIOM and ITCB model Bunn coffee machines.
How to Calibrate the Flow Rate
You must first calibrate the flow rate on your Bunn coffee maker before you can use it. This is essential to optimizing the water to coffee ratio and, ultimately, the taste of the brew. It’s also important to note that the coffee machine’s flow rate will vary based on the coffee maker and location.
Step 1. Get a Measuring Pitcher
The first thing you’ll need is a container (a minimum of 60oz) to measure the amount of water dispensed. This is important for step 5, when the machine will ask you to enter the number of fluid ounces in your container.
Step 2. Go to the Level 2 Programming Menu
To do this, press the right hidden button for 5 seconds or until you see “Calibrate Flow?” appear on the screen. Before pressing yes, ensure the spray head and funnel are in place with the measuring pitcher underneath.
Note: The hidden button is directly right of the digital display.
Step 3. Select “Yes”
To select “yes,” press the button on the right directly underneath the digital display. The machine will then ask you “Container Rdy?” Press the right button again to continue. If you’re using an ITCB model, it will ask you a few additional questions. Just press “yes” to continue.
Step 4. Press the “Brew” Button
If this is a dual dispenser, be sure to press the “brew” button on the left-hand side. The coffee machine will run for a total of sixty seconds. Wait until the water has stopped dripping before completing the next step.
Step 5. Enter the Volume Collected
Next, the screen will display how many fluid ounces it thinks it’s dispensing with a plus and minus sign beneath for you to adjust the value. If the volume is less, press the button underneath the minus sign and if it’s more, press the button underneath the plus sign. To select enter, press the middle button.
Step 6. Calibrate the Right Side (For Dual Dispensers Only)
To calibrate the right side, repeat steps 1-3 and then select the “brew” button on the side you haven’t done, being careful to have the spray head, funnel and measuring pitcher all in place before brewing. With the final step completed, you have now calibrated the flow rate on your Bunn coffee machine!
How To Calibrate the Temperature Sensing Probe
If you need to replace the CPU, CBA or thermistor, then you must calibrate the temperature sensing probe before installing any of these components.
Step 1. Unplug the Machine & Remove the Lid
Depending on your machine, the lid may be screwed in place. You will need a fine-tipped flathead screwdriver to remove the outer panel.
Step 2. Remove the Temperature Sensor Grommet
You’ll want to remove the grommet to gain access to the water tank. However, ensure that the sensor is always in contact with the water.
Step 3. Heat the Water
Do not test the temperature of the water until the machine is finished heating. Doing so will inaccurately calibrate your coffee maker so that it thinks it’s heating to a higher temperature than it is, resulting in under-brewed coffee or tea.
Step 4. Measure the Temperature
For this step, you will need a digital thermometer. Dip the probe into the water to the same depth as the factory temp probe and record the temperature.
Step 5. Go to the Level 3 Programming Menu
To do this, hold the right hidden button until the screen displays “Cal Temperature Sensor?” The hidden button is directly right of the digital display.
Step 6. Select “Yes”
To select “yes,” you need to press the button on the right-hand side directly underneath the display screen.
Step 7. Enter the Results
The machine will display the temperature it thinks the water is. If this number differs from your results, use the plus or minus buttons to enter the temperature you recorded in step 5.
Check out our collection of Bunn coffee maker manuals for more calibration and maintenance tips.