Vacuum Coffee Pot: How Does it Work?

So, how does a vacuum coffee pot work? It has two containers usually one on top of the other. The two containers are connected by a tube that nearly goes to the bottom of the lower container. On top of this tube is a filter.

Before you go further, it may be a good idea to have a look at this YouTube video to see the vacuum coffee pot in action.

You pour water into the bottom part and put ground coffee in the upper part. Then you heat up the water. As the water heats up it generates vapor. The vapor creates pressure and this pressure pushes the water up the tube into the upper compartment until such point that the water level in the bottom chamber is lower than the bottom end of the connecting tube.

Now you have most of the water in the upper chamber where it is brewing the coffee. You carry on heating up the lower chamber and the generated vapor escapes into the top container through the tube. This vapor keeps the water in the upper chamber at the ideal temperature for brewing coffee. You let the coffee brew like this for 1 to 3 minutes.

Now you turn off the heat - what do you think happens next? Yes, the lower chamber starts to cool down and no more vapor is generated. In fact some of it starts to condense back into liquid form. This lowers the pressure in the lower part and the resulting vacuum pulls the brewed coffee from the top chamber back to the bottom via the tube. And, since there is a filter at the top of the tube, the coffee grounds stay at the top.

Now you take off the upper part with the tube and you are left with crisp and delicious coffee at the bottom container.

Further Reading

Vacuum Coffee Maker
Bodum Santos Coffee Maker