• SkillCat Team


Updated: Mar 16

EPA 608 Type 3 Chapter 1 (Take full course for free)

In this module, we will learn about the meaning and different types of appliances included in EPA Type 3. We will go through the features of Type 3 appliances in this introductory module. Skip to quiz!

1. Definition of Type 3 Appliances

EPA Type 3 covers low-pressure appliances. Technicians working on a Type 3 appliance must be certified as either a Type 3 or a Universal technician.

Recall that the EPA Type 1 covers Small Appliances like small refrigerators and air conditioners. EPA Type 2 covers high-pressure refrigeration appliances. Commercial, industrial and large residential systems are included in it.

Type 3 appliances are classified as low-pressure appliances. This is because the pressure inside these appliances is comparatively lower than the outside atmospheric pressure. Recall that the atmospheric pressure is the pressure surrounding us.

Recall that the atmospheric pressure is 14.7 psi. The pressure inside a Type 3 appliance is anything below the atmospheric pressure of 14.7 psi. Pressure lower than the atmospheric pressure is called vacuum.

Vacuum essentially means any pressure lower than the atmospheric pressure. Type 3 appliances have a pressure lower than atmospheric pressure. So they are known to work in a vacuum. A vacuum cleaner is the best example of a device that works in a vacuum.

Recall that any matter flows from a high to low pressure. A vacuum cleaner creates a low-pressure (vacuum) that sucks all the air and dirt. Similarly, the vacuum in a Type 3 appliance wants to suck everything inside it, but it is tightly sealed.

The main example of a type 3 appliance is a chiller system. Chillers are cooling appliances that work under a vacuum. Chiller systems are mainly used to cool commercial buildings, large office spaces, and for industrial purposes.

2. Low-Pressure Refrigerants

The refrigeration system components in Type 3 appliances are the same as in any other refrigeration system, be it Type 1 or Type 2 systems. The major components include:

  1. Compressor

  2. Condenser coils

  3. Expansion/Metering device, and

  4. Evaporator coils

Recall that during the refrigeration cycle, refrigerant moves through the piece of equipment called the condenser. The condenser converts the refrigerant from gas to liquid. This process removes heat from the refrigerant, cooling it.

Refrigerants used in Type 3 appliances are called low-pressure refrigerants. When using low-pressure refrigerants in low-pressure appliances, the required pressure to convert gas to liquid in the appliance's condenser is very low. So the name, low-pressure refrigerants.

A few examples of low-pressure refrigerants used in Type III systems are:

  1. R-11 (CFC)

  2. R-123 (HCFC)

  3. R-1233zd (HFO)

  4. R-245fa (HFC)

Memorize this list!

3. Conclusion

In this module, we went through the essential features of the EPA Type 3 appliances. We also learned about low-pressure refrigerants and a few examples used in Type 3 appliances.

Question #1: Which of the following refrigerants would be used in a low-pressure appliance?

  1. R-22

  2. R-123

  3. R-410A

  4. R-407A

Scroll down for the answer...


Except for R-123, all the other refrigerants are high-pressure refrigerants. R-123 is not a high-pressure refrigerant. It is a low-pressure refrigerant and not used in Type II systems.

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