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Refrigeration Thermostat: How it works

Refrigeration plays a vital role in food transportation and distribution, in the cold chain business. New or used refrigerated vans or trucks make it possible to transport frozen foods and perishables, across hundreds and thousands of miles. Below is how the thermostat works, in refrigerated vehicles and refrigerators, to improve transportation convenience. 

What is a thermostat?

A vehicle’s thermostat is the component that regulates the temperature of the heating or cooling systems in a vehicle, through its engine, and it determines how effective the engine will operate. It is an important component in liquid cooling.  A refrigerator thermostat is the regulatory device, usually located inside the appliance, behind the interior walls, with a sensor that extends into the refrigeration compartment. It has a handle that allows you to manually adjust the temperature, inside the fridge/freezer.  

What are the Functions of thermostat in a refrigerator?

The function of the refrigerator thermostat is to halt the flow of electricity to the compressor, until the air inside the refrigerator has considerably warmed up. When you turn the knob to your desired temperature, it is the work of the thermostat to maintain that temperature, by controlling the refrigerator’s cooling system, either by turning it on, or off.   This ensures that the temperature inside the refrigerator stays at its optimal range of 330F to 400F. Thermostat can also be used in a number of heating or cooling systems, such as HVAC systems, air conditioners, central heating, refrigerated vans, water heaters, ovens, and incubators. 

How does the thermostat work in a refrigerator?

For food to be kept fresh and microorganisms reduced, a low temperature has to be conserved inside the refrigerator. The thermostat in most commercial freezers/fridge, has a capillary tube, filled with gas. Refrigerators work by transferring the heat inside the machine to the outside.   Freezers alter the state of the refrigerant, circulating within, from a liquid state to a gaseous state. The compressor is the heart of the refrigerator. Its sole function is to pump the refrigerant through the coils. The basic components that control the cooling system include: Compressor, condenser, evaporator, and capillary tube. 

What are the basic types of a refrigerator thermostat?

Thermostats display different functional characteristics, based on the application. There are three main types of thermostat in a freezer. These include: 

Vapour Pressure Models

These are electromechanical equipment, which senses temperature with a bulb that is connected to a diaphragm, by a thin capillary tube. This bulb is filled with a volatile liquid that expands as the temperature rises. It pushes out the diaphragm, which closes an electrical switch that starts the refrigerating system. The liquid volume contracts as the temperature drops, pulling in the diaphragm and opening the switch. This turns off the cooling system. 

Bimetallic Types

Mechanical thermostats functions on the principle of thermal expansion, to switch an electrical circuit on and off. Two forms include: bimetallic strips and gas-filled bellows. Bimetallic strips makes use of a sensing strip that comprises of two different metals that expand and contract, at altered rates. 

Solid State Units

This can also be referred to as electronic or digital thermostats.  It makes use of a microprocessor or semiconductor, to act as a switch, to control the HVAC unit. Solid state thermostats apply electronic elements, which become more or less electrically conductive, as the temperature changes. 

Commercial refrigeration temperature

  • Commercial refrigerators should be kept at 2oC to 30C, and not greater than a temperature of 50C.  
  • An ice-cream refrigerator at -290C to -230C.  
  • A cold room at -230C to -180C 

What are the signs of a bad or faulty thermostat in a Fridge or Freezer?

The thermostat is effective in controlling the temperature inside the fridge. This can be hampered when it becomes faulty, leading to an irregular temperature within the refrigerator, which compromises the high-quality and safety of frozen foods.   A refrigerator thermostat is typically designed to last through the entire service life of the refrigerator, reducing maintenance cost, but these units can become faulty. The following are some signs and symptoms that indicate a bad or failing thermostat in a refrigerator: 

  • Regardless of whatever temperature you set your fridge, a failing or faulty thermostat will not be able to keep your freezer in the correct temperature range.  
  • You will also observe that your refrigerator will keep your food cool, rather than frozen, as it may only operate at a temperature below 40 degrees. 
  • If you do not get a zero reading, when you set your volt-ohm multimeter to RX1, or when you probe the terminals, then it is obviously time for a repair or replacement.  
  • If after cleaning your dirty coils, and reprobing your thermostat, you do not get an infinity reading – sideways eight, then your thermostat is faulty. 
  • In some cases, the thermostat will stop working entirely. 

Importance of refrigerator thermostat in the cold business

Freezing boosts cold businesses, by preserving food quality for a long period, before it is sold. High-risk foods like meats, fish, poultry and vegetables, among others, can be easily kept fresh. Frozen food  transportation is also enhanced. It also ensures that your customers are safe from foodborne diseases/poisoning. An effective thermostat will keep health protectors happy, and off your back.  

Replacing a refrigerator thermostat

Replacing the thermostat of a freezer can be tricky because, using a differently regulated one could affect your cooling system, either by making it run for too long, or run too cold, leading to irreparable damages.  Before you attempt to make a replacement, ensure you move highly perishable food to a cooler, or an alternative space, where your food can still be cooled. Also, wear safety gloves, to protect your hands, and do not engage without adequate safety tools, specified in the refrigerator instruction manual.   Undertaking repairs can be hazardous, if you lack the proper knowledge or understanding of the steps required. A qualified technician is usually advisable, when technical repairs are needed. A replacement thermostat must be designed for your type of fridge. It is advisable to simply replace a damaged thermostat, rather than make attempts at repairs.  Glacier Vehicles provides the best temperature-controlled vehicles, supporting your logistics or transportation buisness. If you want to buy a used refrigerated van, a used freezer van, a new refrigerated van or a new freezer van call, Glacier Vehicles on 0208 668 7579.