The space between the outer and inner wall is filled to about a third of the height with water, so the inner wall has no direct contact with the heat source. As a result, the possibly very hot hotplate first warms the water in the space through the outer wall. While the wall of a single-walled pot can get so hot that the food burns on the pot wall, which is over 100 ° C, the heat energy of the stove is transferred to the water in the space in the simmer pot. This boils at 100 ° C, so it does not heat up above this temperature. As a result, the inner wall of the pot does not warm to more than 100 ° C, which makes it impossible to burn or boil over in the simmer pot. Only when all the water has turned into water vapor can the temperature of the inner wall rise above 100 ° C.
Another version has a removable whistle ( whistle pot) connected to the space in between, which indicates the boiling of the water in between.
The bain-marie used in gastronomy works on the same principle, but is made up of two parts.
- Patent application DE19817086A1 : Simmertopf. Registered on April 17, 1998 , published on October 21, 1999 , applicant: BSW Bayerische Stahlgeschirr-Werke GmbH, inventor: Thomas Münzner, Rudolf Reichert (relates to a special version of the simmer pot, but also explains the basic principle).