Introduction to Walk-In Freezers : Temperature controls

 1. Thermostats and Their Function:

• Thermostats maintain the temperature in a walk-in freezer.
• They determine the temperature in the conditioned space and can display it using a thermometer.
• When the thermostat senses heat above a certain level, it turns on the refrigeration system and starts the compressor.
• The thermostat stops the compressor when the desired temperature is reached.

2. Types of Thermostats:

• Electrical/Mechanical Thermostats:
  • Mounted to the evaporator and use knobs, buttons, and switches.
  • Have a remote bulb sensor.
• Electronic Thermostats:
  • Controlled by buttons, touch screens, or remotely.
  • Can be mounted to the evaporator, coil, cabinet, or both.

3. How Thermostats Work:

• The user sets the desired temperature.
• The thermostat sends electricity to the compressor to maintain this temperature.
• It stops sending electricity when the desired temperature is reached, turning off the compressor.
• Uses a capillary tube filled with gas that expands with temperature increase, pushing on a diaphragm to close a switch and operate the compressor.
• Modern electronic thermostats use thermistors, which change electrical resistance with temperature, allowing the thermostat to read the temperature.

4. Modern Electronic Controllers:

• Replace mechanical thermostats in modern walk-in freezers.
• Provide precise temperature control and can manage the compressor, evaporator fans, and defrost heater.
• Collect usage data for record keeping.
• Can be monitored and programmed over a cloud connection.
• Send alerts through apps, texts, or emails when the temperature is too high or too low.
• Include features like short cycling protection and minimum off time delay.
• Can automatically set defrost times.

5. Choosing a Thermostat:

• Ensure clear and accurate temperature reading for food safety.
• Easy-to-read temperature display.
• Accessible for routine checks, either online or in person.
• Should be National Sanitation Foundation (NSF) certified for proven reliability.

Importance:

• Thermostats help maintain freezers at the desired temperature.
• Accurate temperature readings allow for early problem detection, preventing damage.