temperature transmitter working?

Question

honeywell

Answer 1

Honeywell makes thermostats. If it is what you are asking about then there are many versions.

The basic one is made by resistance welding two thin strips of two different metals, then coil it up. Fix the center end of the coil to the turning knob of a control box, the outer end will rotate with temperature due to the difference of thermal expansion coefficients of the two metals. Attach a sealed glass tube, with a large drop of mercury in it, to the outer end of the coil. On one end of the glass tube, put two electrodes which will be electrically connected to one another when the mercury ball rolls to their end of the glass tube.

Now control the temperature by moving the center of the bi-metal coil to set the levelness of the glass tube. As the temperature gets hotter, the coil rotates the glass tube to roll the mercury ball towards closing a low-current solenoid circuit which then energizes a larger one which turns on the A/C compressor. As the temperature drops, the bi-metal coil retracts to eventually disconnecting the A/C circuit.