Simmerstat

We would like to drink steaming hot tea on Shabbat, but the urn only keeps the water  at a temperature of 80 degrees C. What can be done?

 Many people who thoroughly enjoy a cup of steaming beverage refrain from drinking tea at all on Shabbat, because the water that their urns provide is not is hot enough for them. The usual urns cannot maintain a temperature higher than 90 degrees, because of seasonal temperature differences (between summer and winter) and the fact that different sizes of urn must have identical control systems, which might lead to all the water evaporating if too high a temperature is maintained.

The solution that has been proposed by various manufacturers is to control the water temperature by using a "simmerstat." This is a cyclical timer which turns the heating element on and off in a regular cycle. A radial dial is used to set the ratio between heating and cooling times. After the urn in filled, the dial is set to maximum heating in order to boil the water, and it is then reset to the desired temperature. Since these urns have a selector switch they cannot be considered as a "covered flame" and it is therefore very important to make sure that the water has been fully heated before the beginning of Shabbat. The heat setting must never be changed during Shabbat!

Note: A simmerstat is not the same as a thermostat. The simmerstat does not measure the water temperature, which is a direct function of the timing ratio set by the radial dial. (While there is a small thermostat attached to the usual simmerstat, this does not measure the water temperature but rather the heat dissipation of a small heating element which is part of the simmerstat mechanism. This is used to control the operation of the status switch.)

Since there is no thermostat which is directly sensitive to the water temperature in such urns, the temperature will change depending on how much water is present. It is recommended that several experiments be performed during the week to determine the correct dial setting for the desired amount of water (to prevent too high a rate of evaporation or too low a temperature).

To see a table of various urns and whether they are appropriate for Shabbat use, press here.

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