How is the mat protected from overheating?

MediCrystal mats have double safety systems to avoid overheat.

1. First is the thermostat type, built into the controller chip with the standard thermal sensors. There are 3-8 pieces in the mat, depending on the size. 

These thermometer-type sensors measure the temperature of the mat at different spots and report back to the controller. 

If the controller detects overheating, it shuts off the heating system. 

The same sensors and thermostat controller system are also used for maintaining the set temperature. 

When the mat heats up to the set temperature, it shuts off the heating system. 

When the mat cools down approximately 5° below the set level, it resumes.

2. The second safety system (emergency system) consists of bimetal sensors/auto shut-off switches. 

There are 2-6 bimetal strips in the mat. They are bridged. These strips are used to convert the temperature change into mechanical displacement. 

The strip consists of two strips of different metals, which expand at different rates as they are heated. 

The different expansions force the flat strip to bend one way if heated and the opposite if cooled below its initial temperature.

The metal with the higher coefficient of thermal expansion is on the outer side of the curve when the strip is heated and on the inner side when cooled. 

These bi-metal strips function as the power switches connecting or disconnecting the electrical wires. 

They are fixed into the EMF-free heating cables inside the mat to keep the electricity running through them. 

The setpoint is around 74-77°C (165-170°F). If the thermostat function fails and the mat's temperature rises higher than the maximum temperature level of 158°F, the higher temperature will open contact and mechanically cut off the heating cable, interrupting the electric current powering the heating system. 

When the mat’s temperature goes down, the metal strips cool down as well, and they will close the contacts.

If overheating occasionally occurs (for example, if you put an amethyst pillow on the mat‘s heating surface in the area where there are no temperature sensors ), bimetal sensors will do the standard shut-off. After cooling down, the mat will resume working properly. 

But if the temperature sensors fail or the controller chip does not work properly, bimetals will auto-shut-off, and the mat will not work after this.

Several such bimetal sensors bridged in the mat, and each one will shut off the heating system if the temperature goes too high. 

This is a two-tiered emergency system, and so it is double safe.

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