A hot water thermostat is essentially a temperature-sensitive switch that controls the heating elements in a water heater. When the water temperature drops below the set point, the thermostat activates the heating element to warm the water back up.
Here's a more detailed breakdown of how it works:
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Temperature Sensing: The thermostat doesn't directly contact the water. Instead, it uses a sensor, often a bimetallic strip or a probe, that is thermally connected to the tank. This sensor reacts to the temperature of the tank wall, which is a good indicator of the water temperature inside.
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Bimetallic Strip (Common Type):
- A bimetallic strip is made of two different metals bonded together.
- These metals expand and contract at different rates when heated or cooled.
- As the water temperature changes, the bimetallic strip bends.
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Switch Activation:
- The bending of the bimetallic strip is linked to an electrical switch.
- Cold Water: When the water is cold (below the set temperature), the bimetallic strip bends in a way that closes the circuit, allowing electricity to flow to the heating element. This "call for heat" activates the element.
- Hot Water: When the water reaches the set temperature, the bimetallic strip bends in the opposite direction, opening the circuit and shutting off the electricity to the heating element.
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Temperature Setting: You can adjust the desired water temperature by turning a dial or setting on the thermostat. This adjustment changes the point at which the bimetallic strip activates the switch.
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Heating Element Activation: Once the thermostat switch closes, electricity flows to the heating element. The heating element, submerged in the water, heats the water until the thermostat senses that the set temperature has been reached.
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Cycle Repeats: This cycle repeats continuously, maintaining the water in the tank at the set temperature.
In simpler terms:
Imagine a seesaw. One side is the temperature of the water (sensed indirectly). The other side is the switch that turns the heating element on and off. If the water gets too cold, the seesaw tips, turning on the heater. When the water is hot enough, the seesaw tips the other way, turning off the heater.
