The principle of operation of the thermostat
What is a thermostat? A thermostat is a device used to maintain the desired temperature in a system such as a refrigerator, air conditioner, and other devices. The thermostat works on the principle of thermal expansion of solids.
Bimetal thermostat
A traditional thermostat has two different pieces of metal that are joined together to form a so-called bimetallic strip (or bimetallic strip). The bar acts as a bridge in an electrical circuit connected to your heating system. Normally the “bridge is low”, the strip carries electricity through the circuit, and the heating is on. When the tape heats up, one of the metals expands more than the other so the tape bends slightly.
Eventually, it bends so much that it opens the circuit. “The bridge is over,” the power goes out immediately, the heating goes off, and the room begins to cool. But what happens next? As the room cools, the bar also cools and bends to its original shape. Sooner or later, it reopens to the circuit, causing electricity to flow again, so the heating turns on again.
By adjusting the temperature dial, you change the temperature at which the circuit turns on and off. Because it lasts and the metal strip expands and contracts, the heating does not turn on and off constantly every few seconds, which can be meaningless (and quite irritating). Depending on how insulated your home is and how cold it is outside, it may take an hour or more for the thermostat to turn on again after it turns off.
How a bi-metal thermostat turns on and off
The settings allow you to adjust the temperature at which the thermostat turns on and off.
The settings are connected via a circuit to a temperature sensor (a bimetal, shown here in red and blue), which turns the electrical circuit on and off by bending more or less.
Bimetallic strip (“two metals”) is made of two separate metal strips glued together: a piece of brass (blue) wrapped into a piece of iron (red).
As iron heats up, iron expands less than rice, so as the temperature rises, the double-sided tape curves inward.
The dual strip is part of an electrical circuit (gray path). When the bar is cool, it is straight, so it acts as a bridge through which electricity can flow. The circuit is on and heating is done. When the tape is hotter, it bends and breaks the circuit so no electricity can flow. The circuit is now off.
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