What are thermostats and what are they good for?
Thermostats are intended for switching electric circuits with respect to the temperature measured, in heating circuits it is typically switching a heat source on and off, maintaining a preset temperature. Thermostats are designed for panel mount (e.g. in a boiler), its adjustable knob or reset pushbutton is placed on the panel. The temperature is measured by a sensor connected with the thermostat through a capillary.
Encased thermostats are designed to be mounted where desired. The thermostat is placed inside a plastic case which ensures electric protection. The temperature is sensed either by a sensor at the end of a capillary, or by a direct contact or by a sensor attached to the thermostat box, placed in a sheath.
Adjustable thermostats switch directly a heat source depending on the temperature adjustable by a knob, by a screwdriver or fixed.
Safety thermostats act as a fuse when the adjustable thermostat fails. If the preset temperature is exceeded, it opens its contacts. When the temperature sinks again, contacts either close again (automatic reset models), or do not close and the appliance needs to be reset by pressing a reset pushbutton (more frequent manual reset models).