Optimal Range
Stability Target
Drop During Shot
Recovery Time
Understanding Group Temperature
Group head temperature directly impacts espresso extraction and shot quality. Learn how temperature stability affects your espresso and how to optimize extraction.
Temperature stability at the group directly affects extraction quality - even 1°C variations can significantly impact flavor. The group acts as the final heat exchanger, transferring energy from the boiler to the coffee puck, and its thermal mass determines how well it maintains temperature during extraction.
Different group designs (E61, saturated, Faema) have varying thermal characteristics and recovery times. Understanding your group type helps optimize brewing routines and temperature management. Factors like ambient temperature, shot frequency, and flushing patterns all affect actual brewing temperature at the puck.
✓ Temperature Factors:
- • Group design type
- • Thermal mass
- • Active heating
- • Shot frequency
- • Ambient conditions
Quick Answer
Target 92-94°C (198-201°F) for medium roasts. Measure with Scace device. Flush 2s before brewing. Allow 30s recovery between shots.
Group Head Types
E61 Group
Thermosiphon design with active circulation
- Thermal Mass: Heavy brass construction
- Stability: Excellent when hot
- Recovery: 30-45 seconds
- Flushing: Required for temperature control
- Best For: Home/prosumer use
Saturated Group
Direct boiler contact for maximum stability
- Thermal Mass: Integrated with boiler
- Stability: Best available
- Recovery: 15-20 seconds
- Flushing: Minimal needed
- Best For: High volume cafes
Heat Exchange Group
Fresh water design with temperature surfing
- Thermal Mass: Moderate
- Stability: Requires technique
- Recovery: 45-60 seconds
- Flushing: Essential for consistency
- Best For: Traditional setups
Temperature Measurement
Professional Methods:
- Scace Device: Industry standard
- Thermofilter: Portable option
- Thermocouple: Direct measurement
- IR Thermometer: Surface only
DIY Methods:
- Sticker Thermometers: Approximate
- Water Taste: Experienced baristas
- Shot Analysis: Taste-based tuning
- Machine Display: Varies in accuracy
Optimal Temperatures by Coffee
Light Roasts:
93-96°C (199-205°F) - Higher temp compensates for density and solubility challenges of light roasts.
Medium Roasts:
92-94°C (198-201°F) - Standard range for balanced extraction of traditional espresso profiles.
Dark Roasts:
90-92°C (194-198°F) - Lower temp prevents bitter, ashy flavors from over-extraction of dark roasts.
Stability Factors
What Affects Stability:
- Group Mass: Heavier groups hold temperature better
- Active Heating: Some groups have independent heaters
- Water Flow: Continuous circulation maintains temp
- Ambient Temp: Cold rooms require more management
- Shot Frequency: Back-to-back shots stabilize groups
Temperature Management Techniques
Best Practices:
- Heat Soak: Lock portafilter for 5 minutes before first shot
- Controlled Flush: 2-3 seconds to stabilize temperature
- Consistent Routine: Same timing between shots
- Group Cooling: Flush if too hot, wait if too cool
- Temperature Logging: Track actual vs target over time
Common Problems
Temperature Too Low:
- Sour, under-extracted shots
- Weak crema
- Channeling
- Solution: Longer warm-up, controlled flush
Temperature Too High:
- Bitter, burnt flavors
- Dark, quick-collapsing crema
- Uneven extraction
- Solution: Flush to cool, check PID settings
Related Content
Temperature Stability
PID vs thermostat control
Group Types Explained
E61, saturated, HX
Machine Calibration
Optimize settings
Extraction Science
Perfect extraction
Sources:
- SCA Equipment Standards. "Group Temperature Guidelines." 2024.
- Professional Barista Guild. "Temperature Management." 2024.
- Cliff & Pebble. "Group Head Temperature Guide." 2024.
- Home-Barista.com. "Temperature Discussions." 2024.