Thermostat "NO" (normally open): Thermostat closes at temperature rise. Comes with a blue temperature dial.
Use Normally Closed (N.C.) to turn a heater off when the temperature gets too high (standard heating control).
Thermostat "NC" (normally closed): Thermostat opens at temperature rise. Comes with a red temperature dial.
Use Normally Open (N.O.) to turn a cooler/fan on or activate an alarm when the temperature gets too high (over-temperature protection).
