Figure 13-27 shows a diagram of a simple thermostat used to control a furnace (or other heating

Question:

Figure 13-27 shows a diagram of a simple thermostat used to control a furnace (or other heating or cooling system). The bimetallic strip of different metals bonded together. The electric switch is a glass vessel containing liquid mercury that conducts electricity when it can flow to touch both contact wires. Explain how this device controls the furnace and how it can be set at different temperatures.