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What is an E61 group head?

A thermosiphon group design from 1961, still used across prosumer machines for its temperature stability.

The E61 is a group head design introduced by Faema in 1961 — named for the solar eclipse of that year — and still standard on prosumer machines.

How it works

Water circulates continuously between the boiler and the group by thermosiphon: hot water rises, cools slightly in the group, and sinks back. No pump needed.

The group is therefore always hot and always at a stable temperature, without electronics.

What else it does

Mechanical pre-infusion. The lever-operated cam opens the water path in stages, and line or boiler pressure wets the puck before the pump engages.

A three-way valve, which vents pressure after the shot and gives a dry puck.

Why it endured

It is simple, it has no electronics to fail, parts are universally available, and it works. Sixty years of the same design means anything can be repaired.

The trade-offs

Very slow to heat. 30 to 45 minutes, sometimes longer. It is a large brass mass and there is no shortcut.

Heavy. Several kilos on its own.

It costs energy — keeping several kilos of brass hot all day is not free.

Where you find it

Almost every prosumer HX and dual-boiler machine: Rocket, ECM, Profitec, Lelit, Bezzera, Quick Mill.

Is it better

For temperature stability without electronics, yes. Modern saturated groups and well-implemented PIDs match or beat it, and heat faster.

Last reviewed 8 August 2026