I am trying to make a heating element that would only turn on once the element itself reaches a certain temperature. This element, possibly ceramic, would be dormant until it reached an internal temperature from an external source (liquid) of 100 deg F. Once it is triggered, it would produce heat to maintain the liquid at 100 deg F. Ive been trying to figure out the best way to do this and how much power would be required. Say the liquid, well go with water, was 12 fl oz. how would I build a circuit that can be sensing temperature without using power, and once it reaches the desired temp, turns on the heater until the temperature either goes too high or drops too low so that it is not trying to work too hard. Open to suggestions on heating element types or anything that could help with my project. Thanks in advance!