Editing Heating element (section)

=== Polymer PTC heating elements ===
[[File:Standard zpi medium.jpg|thumb|A flexible PTC heater made of conductive rubber]]
Resistive heaters can be made of conducting [[PTC rubber]] materials where the [[resistivity]] increases exponentially with increasing temperature.<ref>{{Cite patent|country=US|number=6,734,250|status=patent}}</ref> Such a heater will produce high power when it is cold, and rapidly heat itself to a constant temperature. Due to the exponentially increasing resistivity, the heater can never heat itself to warmer than this temperature. Above this temperature, the rubber acts as an electrical insulator. The temperature can be chosen during the production of the rubber. Typical temperatures are between {{convert|0|and|80|C|F}}.

It is a point-wise [[self-regulating heater|self-regulating]] and [[self-limiting heater]]. ''Self-regulating'' means that every point of the heater independently keeps a constant temperature without the need of regulating electronics. ''Self-limiting'' means that the heater can never exceed a certain temperature in any point and requires no overheat protection.