Æ 5.04 Measuring Temperature at the Group

No matter what method the espresso machine uses to control the temperature, it’s important to be able to measure the exit temperature accurately in order to be able to calibrate it. Multi-boiler machines will usually be accurately calibrated by the manufacturers, but if you want to check or adjust the calibration yourself, you’ll need special equipment to measure the temperature correctly.

The reason for this is that in most machines the exit temperature will be affected by the flow rate. Machines are designed to maintain a steady temperature during brewing, when the water flows relatively slowly. If cold water is being pumped into the boiler more quickly than this, the exit temperature may drop.