Informative note.
What is a thermostat?
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.
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. This prevents equipment damage from frequent switching.
A thermostat is an instance of a "bang-bang controller" as the heating or cooling system output is not proportional to the difference between actual temperature and the set temperature; the equipment runs at full capacity until the set temperature is reached, then shuts off. Increasing the difference between the thermostat setting and the desired temperature therefore does not shorten the time to achieve the desired temperature.
The term is derived from the Greek words θερμός thermos, "hot" and στατός statos, "standing, stationary".
"Bang-Bang controller" is:
In control theory, a bang–bang controller (on–off controller), also known as a hysteresis controller, is a feedback controller that switches abruptly between two states. These controllers may be realized in terms of any element that provides hysteresis. They are often used to control a plant that accepts a binary input, for example a furnace that is either completely on or completely off. Most common residential thermostats are bang–bang controllers. The Heaviside step function in its discrete form is an example of a bang–bang control signal. Due to the discontinuous control signal, systems that include bang–bang controllers are variable structure systems, and bang–bang controllers are thus variable structure controllers.
History
Possibly the earliest recorded examples of thermostat control were built by Cornelius Drebbel around 1620 in England. He invented a mercury thermostat to regulate the temperature of a chicken incubator. This is one of the first recorded feedback-controlled devices.
Modern thermostat control was developed in the 1830s by Andrew Ure, a Scottish chemist, who invented the bi-metallic thermostat. The textile mills of the time needed a constant and steady temperature to operate optimally, so to achieve this, Ure designed the bimetallic thermostat, which would bend as one of the metals expanded in response to the increased temperature and cut off the energy supply.
The first electric room thermostat was invented in 1883 by Warren S. Johnson of Wisconsin. Albert Butz invented the electric thermostat and patented it in 1886.
One of the first industrial uses of the thermostat was in the regulation of the temperature in poultry incubators. Charles Hearson, a British engineer, designed the first modern incubator for eggs that was taken up for use on poultry farms in 1879. The incubators incorporated an accurate thermostat to regulate the temperature so as to precisely simulate the experience of an egg being hatched naturally.
What is a thermostat?
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.
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. This prevents equipment damage from frequent switching.
A thermostat is an instance of a "bang-bang controller" as the heating or cooling system output is not proportional to the difference between actual temperature and the set temperature; the equipment runs at full capacity until the set temperature is reached, then shuts off. Increasing the difference between the thermostat setting and the desired temperature therefore does not shorten the time to achieve the desired temperature.
The term is derived from the Greek words θερμός thermos, "hot" and στατός statos, "standing, stationary".
"Bang-Bang controller" is:
In control theory, a bang–bang controller (on–off controller), also known as a hysteresis controller, is a feedback controller that switches abruptly between two states. These controllers may be realized in terms of any element that provides hysteresis. They are often used to control a plant that accepts a binary input, for example a furnace that is either completely on or completely off. Most common residential thermostats are bang–bang controllers. The Heaviside step function in its discrete form is an example of a bang–bang control signal. Due to the discontinuous control signal, systems that include bang–bang controllers are variable structure systems, and bang–bang controllers are thus variable structure controllers.
History
Possibly the earliest recorded examples of thermostat control were built by Cornelius Drebbel around 1620 in England. He invented a mercury thermostat to regulate the temperature of a chicken incubator. This is one of the first recorded feedback-controlled devices.
Modern thermostat control was developed in the 1830s by Andrew Ure, a Scottish chemist, who invented the bi-metallic thermostat. The textile mills of the time needed a constant and steady temperature to operate optimally, so to achieve this, Ure designed the bimetallic thermostat, which would bend as one of the metals expanded in response to the increased temperature and cut off the energy supply.
The first electric room thermostat was invented in 1883 by Warren S. Johnson of Wisconsin. Albert Butz invented the electric thermostat and patented it in 1886.
One of the first industrial uses of the thermostat was in the regulation of the temperature in poultry incubators. Charles Hearson, a British engineer, designed the first modern incubator for eggs that was taken up for use on poultry farms in 1879. The incubators incorporated an accurate thermostat to regulate the temperature so as to precisely simulate the experience of an egg being hatched naturally.
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