2 Refrigeration Fundamentals and Environmental Responsibility

How refrigeration moves heat

A refrigerant circulates through a sealed system, absorbing heat in one place and releasing it elsewhere. In a typical refrigerator, it repeatedly changes pressure and often changes between liquid and vapor. The refrigerant name and charge amount are shown on the appliance label; never identify or substitute a refrigerant by appearance alone.

Most small refrigerators use a vapor-compression cycle. The cycle moves heat rather than creating cold.

The four components

1. Evaporator: Low-pressure refrigerant absorbs heat from the refrigerated space and boils into vapor.

2. Compressor: Draws in the vapor and raises its pressure and temperature.

3. Condenser: Hot, high-pressure refrigerant releases heat to the surrounding air and condenses into liquid.

4. Expansion device: The liquid’s pressure drops as it enters the evaporator, lowering its temperature so it can absorb heat again.

Cooling can be impaired even when the refrigerant circuit is intact. A blocked airflow path, dirty condenser, failed fan, or control problem can interfere with cooling.

Refrigerant impacts and hazards

Refrigerants differ in their environmental and safety properties. Older CFCs and HCFCs can deplete stratospheric ozone. Many HFCs do not deplete ozone but can be powerful greenhouse gases. Some newer alternatives, including certain hydrocarbons, may have lower climate impact but can be flammable. The exact refrigerant determines the hazards and service requirements.

Refrigerants may displace oxygen, cause cold burns if liquid contacts the body, or be flammable, depending on the refrigerant type and concentration. Refrigerant-related risks also include toxicity and other physical hazards. Do not use smell alone to identify a refrigerant.

Recognizing possible leaks

Possible signs of a refrigerant leak or refrigeration-system fault include declining cooling, unusually long compressor operation, oily residue near a joint, or physical damage to tubing. These signs are clues, not proof of a leak: electrical, airflow, control, or door-seal problems can produce similar symptoms.

If a leak is suspected, do not puncture tubing, add refrigerant as a substitute for finding the problem, or intentionally release refrigerant. Identify the refrigerant from the appliance label and use service procedures and safety information appropriate to that refrigerant.

Small appliances and certification

For EPA Section 608 purposes, a small appliance is factory-manufactured, charged, and hermetically sealed, with $5$ pounds or less of refrigerant. Examples include household refrigerators and freezers, room air conditioners, dehumidifiers, vending machines, and drinking-water coolers. The appliance must meet the definition; small size alone is not enough.

A person who services or repairs a small appliance and could reasonably be expected to compromise its refrigerant circuit generally needs EPA Section 608 Type I certification. Work that may compromise the circuit includes attaching or removing service hoses, adding or removing refrigerant, and opening the circuit.

EPA-approved certification is not required merely for disposal of a small appliance. Separate safe-disposal obligations still apply.

Refrigerant recovery requirements

Before opening a small appliance for service or disposing of it, recover refrigerant using equipment certified for that purpose and follow the equipment maker’s instructions. The federal rule provides these alternative recovery methods:

• With recovery equipment made before November 15, 1993, recover $80\%$ of the refrigerant.

• With equipment made on or after November 15, 1993, recover $90\%$ if the appliance compressor is functioning, or $80\%$ if it is not functioning.

• Alternatively, evacuate the appliance to $4$ inches of mercury vacuum.

These are alternative regulatory methods, not directions to vent refrigerant or open the circuit before recovery. Certified equipment must be used and operated as required by the applicable rule and the equipment manufacturer’s instructions.

Environmental responsibilities

Section 608 generally prohibits intentional venting of refrigerants while maintaining, servicing, repairing, or disposing of refrigeration equipment. A limited allowance for small, unavoidable releases during good-faith recovery does not permit deliberate venting. EPA has specific, use-dependent exceptions for certain substitutes, so do not assume a refrigerant or appliance is exempt; check the exact refrigerant and applicable requirements.

Good practice protects people and the environment: keep the circuit sealed when possible, use proper recovery equipment and low-loss connections, avoid mixing refrigerants, and keep recovered refrigerant contained for reuse, recycling, reclamation, or proper disposal as applicable.

When equipment is discarded, the final person in the disposal chain must ensure that refrigerant is properly recovered or verify that it was recovered previously.