A thermostat is a component of a control system which senses the temperature of a system so that the system's temperature is maintained near a desired setpoint. The thermostat does this by switching heating or cooling devices on or off, or regulating the flow of a heat transfer fluid as needed, to maintain the correct temperature. The name is derived from the Greek words thermos "hot" and statos "a standing".

A thermostat may be a control unit for a heating or cooling system or a component part of a heater or air conditioner. Thermostats can be constructed in many ways and may use a variety of sensors to measure the temperature. The output of the sensor then controls the heating or cooling apparatus. A Thermostat may switch on and off at temperatures either side of the setpoint the extent of the difference is known as hysteresis and prevents too frequent switching of the controlled equipment.

The first electric room thermostat was invented in 1883 by Warren S. Johnson. Early technologies included mercury thermometers with electrodes inserted directly through the glass, so that when a certain (fixed) temperature was reached the contacts would be closed by the mercury. These were accurate to within a degree of temperature.

Common sensor technologies in use today include:

  • Bimetallic mechanical or electrical sensors
  • Expanding wax pellets
  • Electronic thermistors and semiconductor devices
  • Electrical thermocouples

These may then control the heating or cooling apparatus using:

  • Direct mechanical control
  • Electrical signals
  • Pneumatic signals

Read more about ThermostatHeat Pump Regulation, Dummy Thermostats

Other articles related to "thermostat, thermostats":

Pontiac Fiero - Problems and Issues - Cooling System Issues
... operating temperature of 220 °F (104 °C) prior to the recall switching to a 195 °F (91 °C) thermostat, the midmounted engine utilized long pipes to carry ... Simply pouring coolant into the thermostat housing (on the engine) would leave an air bubble in the radiator, while adding coolant just to the radiator would leave ... Proper procedure (with engine idling and the thermostat removed, filling the thermostat housing, popping the bubble out of the radiator by cracking open the radiator cap until coolant exits) must be ...
Dummy Thermostats
... It has been reported that many thermostats in office buildings are non-functional dummy devices, installed to give tenants' employees an illusion of control ... These dummy thermostats are in effect a type of placebo button ... However, these thermostats are often fully functional in the sense that they are used to detect the temperature in the zone, even though their controls are ...
Electricity On Shabbat In Jewish Law - Practical Applications - Thermostats
... Some rabbinic authorities have questioned that if a thermostat for a heating or air conditioning system is set prior to the start of Shabbat, if changes ... is action that intentionally triggers the thermostat for example, if the thermostat is set to turn on the room's heat, and an occupant of the room wishes the heater would ... that the example of intentionally letting cold air into the room to operate the thermostat constitutes a violation of Shabbat, if the person opens the window for some other, legitimate, reason, and the cold air ...
Wax Thermostatic Element - Automotive Thermostats
... The internal combustion engine cooling thermostat maintains the temperature of the engine near its optimum operating temperature by regulating the flow of coolant to an air cooled radiator ... This regulation is now carried out by an internal thermostat ... Conveniently, both the sensing element of the thermostat and its control valve may be placed at the same location, allowing the use of a simple self-contained ...
Berendsen Thermostat - Basic Description
... The thermostat suppresses fluctuations of the kinetic energy of the system and therefore cannot produce trajectories consistent with the canonical ensemble ... corrected such that the deviation exponentially decays with some time constant Though the thermostat does not generate a correct canonical ensemble (especially for small ... calculated using the widely known Nosé-Hoover thermostat, which correctly generates trajectories consistent with a canonical ensemble ...