Cup warmer
A tray heated by the boiler beneath it. A warm cup keeps a shot from losing its heat the moment it lands.
Heated by: The boiler beneath
Products example
Read-only showcaseAn espresso machine, outside and in
A product on two artboards: the controls a buyer touches, then the boilers and pump inside the case.
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Everything on this diagram
The same content as the picture, as text: every part and what it says when you open it.
Outside
Brew pressure gauge
Shows the pressure in the group while a shot runs. Espresso is extracted at about 9 bar.
- Target
- About 9 bar
- Shows
- Pressure at the group
Steam pressure gauge
Shows the steam boiler's pressure, which is what decides how quickly milk can be textured.
Typical: 1.2–1.5 bar
Group head
Where the water meets the coffee. A heavy chrome group holds its temperature, so the first shot of the morning tastes like the tenth.
- Style
- E61-type, chrome-plated brass
- Brew temperature
- About 93 °C
Brew lever
Lifting the lever starts the pump and opens the valve to the group. Lowering it ends the shot.
- Up
- Starts the shot
- Down
- Ends it
Portafilter
The handle and basket that hold the ground coffee. It locks into the group with a quarter turn.
- Basket
- Double, 18 g
- Diameter
- 58 mm, the commercial standard
Hot water tap
Draws hot water from the steam boiler, for an Americano or to warm a cup.
Draws from: The steam boiler
Steam wand
Pushes dry steam into milk to heat it and build a fine microfoam. The knob above it opens the steam valve.
- Tip
- Four holes
- Knob
- Opens the steam valve
Drip tray
Catches what the group lets go of after a shot, under a removable grille that holds the cup.
Grille: Removable
Power switch
Switches the machine on. A dual-boiler machine needs about 15–25 minutes before the group is fully up to temperature.
Warm-up: About 15–25 minutes
Inside
Water tank
A removable reservoir at the back, filled from the top. Softened water keeps scale out of the boilers.
- Typical size
- 2–3 litres
- Fill with
- Softened, filtered water
Steam boiler
The larger boiler, kept above boiling to make steam for milk and to supply the hot water tap.
- Temperature
- About 125 °C
- Pressure
- About 1.2–1.5 bar
- Typical size
- 1.5–2 litres
Brew boiler
A second, smaller boiler only for brewing water. Two boilers are the point of the design: brewing and steaming at different temperatures, at the same time.
- Temperature
- About 93 °C
- Typical size
- 0.5–0.8 litres
Heating elements
One element in each boiler, each switched on its own, so neither boiler's temperature waits on the other.
- Per boiler
- One element
- Typically
- 1,000–1,400 W each
Group head
Fed from the brew boiler. The mass of brass around the water path is what keeps every shot at the same temperature.
Fed from: The brew boiler
Rotary pump
A rotary vane pump driven by a motor - quieter than the vibratory pumps in most home machines, and able to run from mains water.
- Type
- Rotary vane
- Quieter than
- A vibratory pump
Over-pressure valve
Opens if the pump would push the group past its limit, so a shot never brews at more than about 9–10 bar.
Limits brewing to: About 9–10 bar
PID controller
A small computer that switches the elements on and off in short bursts, holding each boiler within about a degree of its setting.
- Holds temperature to
- About ±1 °C
- Set from
- The display on the front
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