Refrigerant Recovery for High-Pressure HVAC Equipment
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Refrigerant Recovery for High Pressure HVAC Equipment

Updated: 4 days ago


EPA Type 2 Chapter 3


Refrigerant Recovery


In this module, we will discuss the different refrigerant recovery methods used on high pressure HVAC equipment and a few practical techniques for faster, more efficient recovery. Proper refrigerant recovery is critical for safety, environmental protection, and EPA compliance.


What Is Refrigerant Recovery?


Recall that refrigerant recovery is when a technician removes refrigerant from a system and stores it in an external container or recovery tank. During commercial refrigerant recovery, the goal is always to remove the entire, or maximum possible amount of, refrigerant from the appliance before service, repair, or disposal.


The refrigerant can be recovered in liquid form or vapor form. It is necessary to recover both liquids as well as vapor refrigerant from the system for complete recovery. Let us discuss this a bit more.



Liquid Recovery

While recovering, liquid refrigerant is pulled from the liquid line in the system.

  • Liquid recovery is faster and helps reduce overall recovery time.

  • The pressure on the liquid side is higher, which helps push the liquid out of the system into the recovery tank more quickly.

  • Because refrigerant oil mixes more heavily with liquid, liquid recovery can cause greater loss of refrigerant oil from the system.


The typical sequence is to:

  • Start with liquid recovery to handle the bulk of the refrigerant and achieve higher recovery rates in less time.

  • Then switch to vapor recovery to pull out the remaining refrigerant.


Vapor Recovery

After liquid recovery, the remaining refrigerant is recovered in vapor form.

  • Vapor refrigerant is pulled from the vapor line.

  • Less refrigerant oil is carried with vapor than with liquid, so vapor recovery helps minimize oil loss.

  • However, vapor recovery is slower and can significantly increase recovery time, especially with high pressure refrigerants.


For most high pressure systems and other large cooling systems, technicians begin with liquid recovery and finish with vapor recovery to balance speed and oil management.


Limits Due to Atmospheric Pressure

Recall that atmospheric pressure is the pressure of the surrounding air. Sometimes, leaks in the appliance allow air to enter the system during recovery. If this happens, and the system is open to atmosphere, a complete vacuum cannot be achieved.


In such cases:

  • Recovery from the appliance is only possible down to atmospheric pressure.

  • Below that point, further recovery is not feasible without repairing leaks.

Recovery Time and Speeding Up Recovery


Recovery time is the time it takes to remove the refrigerant from a system. For commercial refrigerant recovery, technicians aim to reduce recovery time while staying within safety and equipment limits.


Recall the main factors affecting recovery time:

  1. Ambient Temperature, and

  2. Hose Length and Size

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We will learn about two more techniques to speed up the recovery process:

  1. Liquid Recovery

  2. Recovery Tank Temperature Control


As already discussed, liquid recovery is faster and reduces the recovery time. Recall that the pressure inside the liquid side is higher. The higher pressure pushes the liquid out of the system into the recovery tank more quickly.


Recall that the pressure and temperature of any substance are directly related. When we cool the recovery tank:

  • The temperature inside the tank decreases.

  • The pressure inside the tank also decreases.

  • Lower pressure in the tank creates more “space” for the refrigerant and reduces resistance to refrigerant flow.


The results being:

  • The pressure difference between the system and the recovery tank increases.

  • Refrigerant moves more quickly into the tank.

  • Overall recovery time and recovery rates improve.


In other words, keeping the recovery tank cool is a simple way to achieve more high efficiency recovery on high pressure HVAC equipment and other large cooling systems.


In this module, we discussed the different refrigerant recovery methods. We also learned a couple of techniques for faster recovery.




Recovery Equipment



In this module, we will discuss the main pieces of commercial refrigerant recovery equipment used in the field. We will also review a few important steps to perform before starting the recovery process.



Essential Recovery Equipment

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The main pieces of equipment necessary to perform refrigerant recovery from any system are:

  • Recovery Machine (or refrigerant recovery machine)

  • Recovery Tank (certified refrigerant cylinder)

  • Digital weighing scale

  • Low-loss fittings and gauges


A recovery machine contains a compressor to suck out the refrigerant during recovery. This recovery unit can handle high pressure refrigerants used in many commercial systems. There are a few different types of recovery units; two of which we will be discussing here:

  • Hermetic Recovery Units

  • Water-Cooled Recovery Unit



Hermetic Recovery Units

Recall that a hermetic compressor has all its components sealed in a single shell. A hermetic recovery machine uses a hermetic compressor uses this type of compressor.

  • The compressor motor produces a lot of heat during operation.

  • Hermetic recovery machines depend on the flow of recovered refrigerant to cool the compressor.


A deep vacuum in a system is very close to zero pressure. Drawing a deep vacuum means that minimal refrigerant is left in the system, which needs to be sucked out.

Hermetic recovery machines depend on the flow of recovered refrigerant to cool it down. When drawing a deep vacuum, the compressor motor overheats as there is little refrigerant flow to cool it down. This overheating is a drawback of hermetic units.


Water-Cooled Recovery Units

A water-cooled recovery unit uses a condenser coil that cools down the recovered vapor refrigerant and converts it back to liquid. The recovery unit's condenser coil is similar to the condenser coil in a refrigeration appliance.


The condenser coil in the recovery unit works similarly to the condenser coil in a refrigeration appliance. Local municipal water supply is passed over the condenser coil to cool it.


Water-cooled recovery units are typically used to recover large amounts of refrigerant in:

  • Commercial refrigeration systems

  • Other large cooling systems

  • Service chillers and similar high capacity equipment


Because they handle high loads and maintain better cooling, they provide high efficiency recovery and stable recovery rates on high pressure refrigerants.


Low-Loss Fittings and Gauges

Recall that recovery hoses and gauges are connected to the appliance for tasks like recovery, evacuation, and troubleshooting. All pieces of equipment used for any such purposes and manufactured after November 15, 1993, must be equipped with low-loss fittings.

Low-loss fittings minimize the loss and venting of refrigerant fluid while connecting and disconnecting the hoses to the appliances' service valves. Self-sealing connectors and hand valves are few types of low-loss fittings.

Self-sealing connectors only require screwing or unscrewing of the cap and no force to connect them to the appliances' service valves. Similarly, hand valves only require the technician to turn a valve.

Note: It is not necessary to report the purchase of any recycling and recovery equipment to the EPA, but it must be used according to EPA rules.


Processes Before Recovery


Before starting with the recovery process, a few steps related to the recovery equipment must be followed.

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  1. Evacuate the recovery cylinderBefore transferring refrigerant into an “empty” cylinder, it is necessary to evacuate the cylinder first.

    • The cylinder may contain air, which is non-condensable.

    • We want to avoid mixing air with the recovered refrigerant.

    • EPA best practice requires evacuating the cylinder before use.


  2. Change or inspect filters

    All recovery machines have a filter at their inlet to remove solid contaminants from the refrigerant. After recovery, this filter can trap traces of the previous refrigerant.


    Recall that mixing two refrigerants is prohibited.

    • Before starting recovery on a different refrigerant or a new appliance, the recovery machine’s filter should be replaced.

    • This avoids cross-contamination of refrigerants and protects both the equipment and recovered refrigerant.


  3. Check the scale and cylinders

    • Verify that the digital weighing scale is functioning correctly.

    • Monitor the recovery tank and ensure it is never filled beyond 80% of its capacity, to prevent dangerous pressure situations.


In this module, we discussed the pieces of equipment used for the recovery process and the key steps to follow before recovery.







Recovery Precautions


In this module, we will discuss the different precautions to take during a recovery process, and some techniques to follow for safe, compliant refrigerant recovery, especially when handling high pressure refrigerants.



General Recovery Process Precautions


Recall that venting refrigerants into the atmosphere is prohibited. Before starting recovery, a few precautionary steps are necessary to prevent venting and protect both the technician and the environment.


A technician should always:

  • Check service valve positions

    A technician should always inspect service valves before starting recovery to make sure no valve is left open by mistake.

  • Check recovery machine oil level

    Recovery machines that use oil for lubrication must be checked before starting recovery.

    • Low oil levels can damage the recovery machine.

    • A damaged compressor can cause leaks and accidental venting.

  • Wear appropriate PPE

    Technicians should wear personal protective equipment (PPE) such as safety goggles and gloves during refrigerant recovery to prevent exposure and frostbite.

  • Monitor cylinders and data

    • Document the date, type, and quantity of recovered refrigerant for EPA compliance.

    • Track when refrigerant is recycled, reused, or sent for reclamation.


Parallel Compressor Systems

A parallel compressor system has multiple compressors used in a single appliance. The compressors are connected in parallel so that all the compressors have a single outlet supply to one single outlet line.


It is also famously known as a parallel rack system. Such systems are commonly found in supermarket refrigeration and large multiplex systems.


Because the outlet is common, the pressure in the outlet line will be equal to the pressure produced by a single active compressor. As all the compressors supply to a single outlet line, it is called an open equalization connection.


To recover the refrigerant from these systems, it is necessary to isolate these parallel compressors. This is because even if a single compressor is not isolated it can restart the refrigeration cycle by pushing refrigerant into the system from another compressor’s pressure, making full recovery difficult and increasing the risk of venting.


Recovered Refrigerant and Impurities

Recall that recovered refrigerant may contain impurities like

  • Refrigerant oil

  • Moisture

  • Acids and

  • Solid particle impurities


We will discuss a bit about refrigerant oil being an impurity.


Recall that refrigerant oil is mixed with the refrigerant. The refrigerant oil mixed with refrigerant cannot be filtered out and reused. So the oil recovered along with refrigerant is nothing but impurity removed.


Recovered refrigerant:

  • Can be recycled (cleaned and reused in similar systems) or

  • Reclaimed (processed back to industry purity standards, such as ARI 700, at an approved facility).


These steps help reduce the need to purchase new refrigerants and support environmental and economic goals.


System-Dependent (Passive) Recovery

System dependent recovery uses the pressure of a functioning compressor or the internal system pressure to recover refrigerant. This is also called passive recovery.


If we connect a non-pressurized refrigerant container to the system, the pressure of the container is lower than the pressure inside the system. The refrigerant will naturally flow from high pressure to low pressure, helping us recover our refrigerant without an active recovery machine. This is how system-dependent recovery works.


System dependent recovery is limited to appliances with 15 pounds or less of refrigerant. Using this method for appliances having more than 15 pounds is not feasible and is prohibited.


For larger or high pressure HVAC equipment, an active refrigerant recovery machine with appropriate recovery capacity must be used.



Specific Recovery Techniques


Recall that the receiver tank is a storage vessel for the refrigerant liquid coming out of the condenser coils in an appliance. The receiver tank also plays a major role during refrigerant recovery and servicing an appliance.


For an appliance with a receiver tank, the refrigerant is generally recovered from the receiver tank outlet. Note that this can only be done if the receiver tank outlet is at a lower height than the condenser coil outlet. If the receiver tank outlet is higher than the condenser outlet, the refrigerant is removed from the condenser outlet.


Recall that a liquid cannot rise from a lower position to a higher position without added pressure.


Refrigerant should always be recovered from the lower outlet. This will minimize the risk of venting due to the refrigerant liquid being stuck in the system.


While servicing a unit having a receiver tank, a different technique can be used. Instead of recovering in a refrigerant tank, a technician can pump down the refrigerant into the receiver tank and isolate it.


The receiver tank acts as a refrigerant cylinder and stores the refrigerant in it. Refrigerant is moved and stored in the receiver while the rest of the system is opened for service. This can save time and effort compared to a full external recovery, especially on systems designed for pump-down service.


In this module, we learned about the different precautions to be taken and some techniques to be followed during a recovery process. These techniques and precautions are fundamental to prevent venting, protect your equipment and the appliance from any damage.




Commercial Refrigerant Recovery Machines

In commercial and industrial applications, technicians often use high capacity refrigerant recovery machines designed specifically for high pressure refrigerants and large cooling systems.


Features of modern commercial refrigerant recovery equipment can include:

  • High recovery capacity for both liquid and vapor

  • Oil-less compressor designs for cleaner operation

  • Lightweight and portable construction for easier use on job sites

  • Built-in oil separator and filters to handle contaminated refrigerant

  • High CFM vacuum pumps to speed up recovery of gases and reduce recovery time


Examples of advanced systems in the market include units designed for:

  • Handling tough demands of industrial and commercial recovery

  • Achieving blazing recovery rates on high pressure refrigerants

  • Providing twice the recovery capacity of typical units in their class


Regardless of brand, every refrigerant recovery machine used in commercial work must be:

  • Properly rated for the refrigerant class (Class I, II, III, IV)

  • Equipped for the pressures involved

  • Used with certified cylinders and scales to maintain documentation and EPA compliance








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