What is Pre Infusion?
Pre infusion is a process in which water is introduced to the coffee at a low pressure to allow brewing to begin before the standard 9 bar pressure is sent through the coffee grounds. Pre infusion can help a barista of any skill level pull a more balanced shot or for those who find channeling to be a common problem when pulling those morning shots. The way this works is through the low pressure of pre infusion and the lower flow of water allowing the coffee grounds to saturate slower before 9 bar pressure and higher flow is introduced to the coffee puck by the pump. This helps create an even, balanced shot that anyone can enjoy.
Pre Infusion on the A53
Pre infusion on the plumbed in A53 model is a programmable feature. A user is able to select in one second increments between having 0 seconds of pre infusion set, to having up to an 8 second pre infusion period. This is a passive pre infusion process with the plumbed in A53, meaning that when the one or two cup button is pressed to begin the shot, the brew solenoid opens up, allowing water to flow through passively at line pressure, but the pump does not turn until the programmed number of seconds is met. This will allow water into the portafilter, so that it can begin interacting with the coffee grounds. When the pre infusion time is met, the pump will then turn on and begin pushing water through the coffee puck at 9 bar pressure for the remainder of the shot.
Setting pre infusion on the A53:
With machine on, hold down the power button for 5 seconds until "95", the power light, and the "boiler" light are blinking.* This is programming mode.
*Note: If your coffee boiler is set to a higher or lower temp., that is the number that will be blinking, i.e. a boiler set to 90 will be blinking on "90", power light and boiler light.
From programming mode, hold down the "B" (boiler button) for 5 seconds until the number is not blinking but the boiler and power light remain blinking. You are now setting the length of pre infusion. Each number, 85-ECO, represents 1 second of pre infusion time, i.e. 95 is 3 seconds of pre infusion.
Tap the boiler "B" button until the desired number of seconds is displayed, indicated by all the numbers lit up from 85 to the setting you selected (85-your setting will be lit).
When you are satisfied with the number of seconds, tap the power button to exit out of programming mode and back to normal function.
Pre Infusion on the A53 Mini
Pre infusion on the A53 Mini is different because of the vibratory pump on the A53 Mini. Pre infusion on the A53 Mini is made through a chamber that is installed at Clive which creates two different paths for the water to flow. Instead of all of the pump pressure and flow moving through the group head it also sends flow to the pre infusion chamber which has a spring that, as pressure builds, compresses and allows more water to enter the chamber. This means that over the first 7-9 seconds of extraction less water and pressure is being introduced to the puck, because it is traveling to both the group head and the pre infusion chamber. The extra water introduced to the pre infusion chamber is released at the end of the shot through the relief valve.