Operation Manual

Pressure Builds

14 The infusion valve is pushed open by the pressure of

the incoming water (direction of ﬂow indicated by the

blue arrows). The space below the infusion valve begins

to ﬁll with water. During the time it takes to ﬁll this void,

the pressure in the entire brew path cannot exceed that

which is determined by the force of the spring which

normally holds this valve in the closed position. This

water at low pressure is pre-wetting (“infusing”) the cof-

fee at this time.

15 The exhaust valve at the bottom of the group is held by

a much stiffer spring which exerts a force greater than

the brewing pressure. This valve will remain closed, as

seen here, until the user lowers the lever back to the ful-

ly-down, “at rest” position.

16 Once the infusion chamber is completely ﬁlled, the en-

tire brew path reaches the maximum brewing force from

the pump. This increase in pressure will be obvious if

you are watching the brew pressure gauge.

17 When that equilibrium in pressure is achieved, the in-

fusion valve will close, and it will stay in that closed

position for most of the extraction process, as long as the

pressure above and below that valve are equal.

18 Pressure also builds over the coffee at this time, and

now the extraction begins in earnest.