Brew Gauge - Espresso Series

Brew Gauge - Espresso Series



Brew Circuit Gauge Characteristics & Troubleshooting - Espresso V3 & Single Group


Each group on a SLAYER Espresso V3 & Single Group features a gauge connected directly to the brew tank. Brew gauges indicate several hydraulic brew circuit states: idle line pressure, live extraction pressure, and thermal expansion. All of which are helpful to understand when brewing espresso and troubleshooting. 



Parts:
  1. 99000-50330 BREW GAUGE ASSEMBLY
Tools:
  1. Blank Portafilter
  2. Espresso Brewing Equipment
Gauge Characteristics & Terminology:

Free Flow / Zero Resistance
  1. Gauge: 0
Group is actuated to either Pre or Full Brew without the resistance of extracting coffee or a blank portafilter.
Zero pressure is being built within the brew circuit.


Video illustrates actuating through brewing phases. Notice brew gauge starts at line pressure and remains at zero bars until actuated to the OFF position (gauge indicates return to line pressure).
Line Pressure:
  1. Gauge: 3-5 bars
The brew circuit on all SLAYER Espresso machines is an open hydraulic pathway from inline water (Save a few check valves along the way to prevent backflow!). Gauges will reflect line pressure while idle and not actively heating (as indicated by infrequent or lack of illuminated heating indicator colons).

Once actuated to the OFF position. Brew gauge will jump to line pressure. However, to maintain temperature stability, gauge will steadily begin to climb towards expansion pressure. See Heating Circuit Pressure below.

While idle, the autofill circuit may activate to maintain water level within the steam tank. This will cause the brew gauges to dip in pressure (Espresso V3 & Single Group autofill circuit is fed via pump pressure). As a measure to maintain brew pressure stability during espresso extraction. Actuating the brew circuit will interrupt an autofill cycle. Autofill circuit will immediately activate once the brew actuator(s) is returned to the OFF position.  Additionally, autofill circuit will not activate while an espresso extraction is occuring.  

SLAYER recommends an inline water pressure of 3-5 bars at 1.5 GPM. See SLAYER's Installation Cut Sheets for more information.

Resistance Pressure:
  1. Gauge: 0-9 Bars (Pump Activated)
  2. Gauge: 10 Bars (Pump Activated + Blank Portafilter)
During coffee extraction, gauge starts at 0. Upon actuating to Pre-Brew, pressure slowly builds within the brew circuit. Since the Needle Valve restricts flowrate and not pressure the gauge reflects a slow advance towards 9 bars.
  1. Calibrate Needle Valve - Espresso Series
Once actuated to Full-Brew, the Needle Valve solenoid activates and allows full flowrate water to travel through the brew circuit. Brew gauge will immediately jump to 9 bars. Actuating OFF discharges back pressure.

When calibrating or adjusting pump pressure. Engaging a blank portafilter into the group and actuating to Full-Brew will see an immediate jump to 10 bars.
  1. Pump Adjustment - Universal
10 bars, set with a blank portafilter, is the recommended starting point for brewing espresso under pressure.  

Heating Circuit Pressure:
  1. Gauge: ~11/12 Bars (Thermal Expansion)
While actively heating (as indicated by the presence of illuminated heating indicator colons), the brew gauge will climb to ~11/12 bars due to thermal expansion. Excess water caused by thermal expansion is 'burped' from the expansion valve.



It is not uncommon to observe the gauge remain near ~ 11/12  bars while idle after heating cycle.

Troubleshooting:
SLAYER recommends all service be performed by an experienced SLAYER Espresso trained technician. For a technician reference near you, please contact SLAYER Support at (206)-281-7171 (#1 in Directory) or email support@slayerespresso.com.

Adjust pump. 
  1. SLAYER Espresso V3 and Single Group models utilize the brew gauge to calibrate brew pump pressure.
  2. Pump Adjustment - Universal
Gauge reads 10 bars immediately upon actuating to Pre or Full Brew.
  1. Diagnose solenoid valves along brew circuit.
Suspected inaccurate gauge.
  1. Verify expansion valve is not discharging pressure below ~11/12 bars.
  2. Confirm 3-way brew valve is functioning properly. 
  3. Replace gauge.


Questions or concerns? Please contact support@slayerespresso.com

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