DIYbanter - View Single Post - Capillary thermmostat vs. Bi-metal ones

Ed Pawlowski

On 10/12/2014 1:37 PM, wrote:
Please enlighten me, what is a capillary thermostat? Do you mean a mercury bottle thermostat?

Bi metal is two unlike metal sandwiched together and they expand at
different rates causing it to bend. That is the types use is the round
Honeywell T-stats in many homes.

mercury expands in a tube or bulb. It can register degrees in a long
tube as an indicator.

Capillary is a thin piece of tubing with usually a bulb of some sort at
one end. As the material inside expand, it pushes a diaphragm and can
operate a tiny switch to make or break a contact. Refrigerators use
that type. Others for gas appliances have a bellows that can work a
valve to control the gas. No electricity needed.

The liquid inside is some sort of silicone than can take both high and
low temperatures.