Vibiemme Domobar Junior - Manual (Page 8)

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3.6 The grouphead
The E-61 grouphead, originally designed by Faema in 1961 (reportedly a year that had an Eclipse, thus
creating the components of the name “E” and “61”) has a thermosyphon design. The Thermosyphon
is a water path from the brew boiler, through the grouphead, and back to the brew boiler. The upper
connection channels hot water into the grouphead (hot water rises) where it transfers heat energy to
the massive amount of metal there. The water cools just a little as it leaves its heat energy in the metal.
This water becomes ‘heavier’ as it cools, and the cooler water “sinks” back into the brew boiler. This
convection current continues to heat the grouphead while the machine is on (and even for a time after
it is turned off). This helps create a consistent brew temperature throughout the brewing path- a critical
component for quality espresso.
When at rest (as in this first image) the water circulates from the brew boiler, through the grouphead, and
then back through the brew boiler. This flow is indicated by the arrows.
This is a passive system, powered through convection. Note that the brew valve is closed, and the coffee
is isolated from the water flow at this time.
3.6.1. Brewing
When in brewing mode the valve opens and the pump is activated. Hot water, under the force of pressure
created by the pump, forces water through the coffee which comes out the as espresso.
The only path the water can take is through the coffee.