34
FLOWMETER CALIBRATION INSTRUCTIONS
These instructions are to be performed using the flowmeter calibration feature made available with firmware
version 2.64. See page 26 for information on accessing this feature in the programming.
WARNING: It is recommended that this calibration be performed while the machine is cool and the heating
elements are off. Performing the calibration while the machine is hot can lead to errors in desired accuracy.
Materials Needed:
•
Cup (or pitcher, etc.) with at least 250ml capacity and a wide enough mouth to capture water
dispensed from brew group
•
Slotted screwdriver short enough to fit under group head (might need
“
stubby
”
one)
•
Graduated cylinder with 250ml capacity and 2ml resolution or better.
WARNING:
Some users may prefer to use a scale instead of a graduated cylinder. Note that the density of wa-
ter varies as a function of temperature. Grams and milliliters are equivalent for water at 4°C (just above freez-
ing.) However, at brew temperatures water density is closer to 0.97g / ml. Therefore, if you weigh some wa-
ter (in grams) out of a hot brew group and want to calculate its volume (in ml,) you must divide by roughly
0.97.
Calibration Instructions
:
1.
Clean and backflush the brew groups.
2.
Remove the diffuser screens and screws.
3.
Ensure the heating element breaker is off.
4.
In order to make the starting brew pressures more consistent, run each group briefly without the
pump on. This can be done using the BREW VALVES function on the TEMPERATURE DISPLAY
screen found in the 2nd level menu (see page 23).
5.
In the 2nd level menu, cycle to the FLOWMETER CALIBRATION screen. (see page 26)
6.
Position the cup under the 1st brew group
7.
Follow the on screen prompts to dispense a test volume of water into the cup. The machine will automati-
cally stop when the test volume of water has been dispensed (approximately 250 ml).
8.
Carefully transfer the water from the cup into the graduated cylinder and measure the volume.
9.
Enter the measured volume on the screen.
10.
Proceed to the next brew group, repeating steps 6
-
9 until all groups are calibrated.
11.
Return to the TEMPERATURE OVERVIEW home screen.
Optional Verification:
Note
: the verification step does not utilize the calibration program, but is intended to verify that the calibra-
tion was successful.
1.
In the first level menu, adjust the volume for program 1 on each group up to 444 TOTAL WATER COUNT.
2.
Run program 1 on all of the brew groups for a few seconds to get each group up to pump pressure.
3.
Position the cup under the 1st brew group.
4.
Run program 1 to dispense 444 ticks worth of water into the cup.
5.
Verify with the graduated cylinder that the group has dispensed 100ml of water.
6.
Proceed to the next brew group, repeating steps 3
-
6 until all of the groups are verified.
7.
Turn the heating elements back on and reinstall the diffuser screens and screws.
