tags: [] - coffee/brewing - coffee/brewing/immersion - coffee/equipment aliases: - Vacuum pot - Siphon brewer - Vac pot - Vacuum siphon

Siphon (Vacuum Pot)¶

Tags: #coffee/brewing #coffee/brewing/immersion #coffee/equipment Aliases: Vacuum pot, Siphon brewer, Vac pot, Vacuum siphon Related: Brewing Methods MOC | Coffee Extraction Fundamentals MOC | French Press | Brewing Fundamentals MOC | Coffee Equipment MOC Status: ✅ Complete

Overview¶

The siphon, also called the vacuum pot or vac pot, is a two-chamber glass brewing device that uses vapour pressure and vacuum to move water between chambers, producing a clean, aromatic, full-bodied cup through full immersion extraction. Water is heated in the lower chamber until vapour pressure forces it upward through a sealed tube into the upper chamber where coffee grounds wait; when the heat source is removed, cooling air contracts in the lower chamber and draws the brewed coffee back down through a filter, separating liquid from spent grounds. The siphon's theatrical process — liquid rising and falling in glass vessels over an open flame or beam heater — has made it a centrepiece of specialty café theatre and a respected tool for highlighting the delicate aromatic qualities of high-quality single-origin coffees.

History¶

The siphon's invention dates to the 1830s. Several independent patents were filed across Europe during this period:

1830: A French patent by Mme. Vassieux described a two-chamber glass brewing device operating on vapour pressure principles
1838–1841: Scottish marine engineer Robert Napier developed a commercial version for the British market
1840s: German glassmaker Johann Burschbaum and others refined the design for domestic use

The device was popular throughout Europe and the United States in the late 19^th and early 20^th centuries, prized for producing a cleaner cup than the boiled coffee and drip pots of the era. It declined with the rise of automatic drip machines but was preserved and refined in Japan, where siphon brewing (saifon) became central to the Japanese coffee shop (kissaten) culture of the mid-20^th century. Japanese manufacturers — particularly Hario, Yama, and Kinto — became the primary global producers of modern siphon equipment. The specialty coffee movement's third wave renewed interest in the siphon as a precision and presentation tool.

Equipment¶

A complete siphon setup consists of:

Component	Description
Lower chamber (bulb)	Heat-resistant borosilicate glass globe; holds water; sized 3–8 cup capacity
Upper chamber (hopper)	Funnel-shaped glass vessel; holds grounds during extraction; fits into lower chamber via a rubber or silicone gasket seal
Connecting tube	Glass siphon tube with filter attachment at base of upper chamber
Filter	Cloth, metal mesh, or paper; fitted to base of upper chamber to retain grounds
Heat source	Butane or alcohol beam burner (tabletop); halogen beam heater; stovetop adaptor
Stand	Frame that holds lower chamber over heat source during brewing

Cloth filters produce the fullest body; paper filters produce the cleanest cup. Cloth requires careful cleaning and periodic replacement to prevent rancid oil build-up.

Brewing Process¶

Setup and Preheat¶

Add measured water to the lower chamber and bring to a boil over the heat source
Attach the upper chamber to the lower via the gasket seal while water heats — do not tighten until ready, to prevent pressurisation issues
Add ground coffee to the upper chamber before attaching, or after water rises

Water Rise (Vapour Pressure)¶

As water approaches boiling in the lower chamber, steam pressure builds and forces water upward through the connecting tube into the upper chamber. A small volume of water remains in the lower chamber as a vapour bubble, preventing the upper chamber from emptying entirely.
Once most water has risen, reduce heat to maintain a stable sub-boiling temperature (approximately 92–96 °C) in the upper chamber — full rolling boil in the upper chamber is undesirable as it over-extracts.

Immersion Extraction¶

Stir the coffee slurry gently but thoroughly immediately after the water rises, and again at the midpoint of the immersion period. Consistent stirring is critical for even extraction.
Brew for 60–90 seconds of immersion (exact time varies with grind size and recipe).

Drawdown (Vacuum)¶

Remove the heat source completely. As the lower chamber cools, the vapour bubble condenses, creating a partial vacuum that draws the brewed coffee downward through the filter and tube at high speed.
Drawdown takes 30–60 seconds. A clean drawdown that removes all liquid from the upper chamber is a sign of correct grind size and filter condition.
Remove the upper chamber from the lower, wipe the exterior of the lower chamber, and serve directly from the bulb.

Typical Recipe¶

Parameter	Value
Coffee dose	15 g per 250 ml
Grind size	Medium-fine — finer than French press, slightly coarser than espresso
Water temperature	92–96 °C in upper chamber
Immersion time	60–90 seconds
Total brew time	5–7 minutes

Extraction Character¶

The siphon produces a cup that is distinct from other immersion methods:

Clarity: High — finer than French press due to filtered drawdown; cloth filter produces more body than paper
Body: Medium to full; more body than most paper-filtered pour-overs
Aroma: Exceptional — the open-top brewing and stirring volatilise aromatic compounds effectively; siphon is particularly valued for aromatic coffees
Temperature: Brewed coffee is served very hot directly from the heated lower chamber
Consistency: Moderate technique sensitivity — stirring consistency, timing, and heat management all affect extraction

Cleaning and Maintenance¶

Siphon equipment requires careful post-brew cleaning:

Cloth filters must be rinsed immediately after use, stored in cold water in the refrigerator, and replaced when they become permanently discoloured or develop off-odours
Glass chambers should be rinsed with hot water promptly — dried coffee oils are difficult to remove and taint subsequent brews
The gasket seal should be checked regularly for cracks or hardening, which cause loss of pressure and failed water rise

Key Facts¶

Invented independently in France and Scotland in the 1830s
Preserved and refined in Japan; Hario, Yama, and Kinto are the principal modern manufacturers
Uses vapour pressure (upward) and vacuum (downward) to move water between chambers
Immersion time is typically 60–90 seconds at sub-boiling temperature in the upper chamber
Cloth filter produces fuller body; paper filter produces greater clarity
Particularly effective at expressing volatile aromatic compounds in high-quality single-origin coffees
Considered one of the most technically demanding manual brewing methods due to heat and timing management

References¶

Hoffman, J. (2018). The World Atlas of Coffee, 2^nd ed., Mitchell Beazley
Ukers, W.H. (1922). All About Coffee, The Tea and Coffee Trade Journal Company
Specialty Coffee Association, Brewing Methods Compendium, 2021
Hario Co., Ltd., Siphon Brewing Guide, hario.com

Changelog¶

Date	Change
2026-04-27	Note created

This article is part of All-About-Coffee.com - The comprehensive coffee knowledgebase.