Group head temperature

The actual temperature of water at the group head, where it meets the puck — not the same as the boiler set temperature. Group temperature is what determines extraction.

Why it matters — There's always a temperature loss between boiler and puck. On saturated groups, the loss is small (1–3 °C); on E61 groups, it depends heavily on warm-up state and recent use; on thermoblock machines, it can swing several degrees during a shot.

Good to know

• Measuring group temperature directly requires a Scace or a portafilter-mounted thermometer.
• For most users, learning your machine's habits — flush patterns, warm-up time, idle behaviour — is more practical than measuring the temperature literally.