Common Recovery Methods Explained

The three different recovery methods are: vapor recovery; the push-pull method; and the liquid recovery method.


Vapor Recovery
In the vapor recovery method, the refrigerant is removed from the HVAC system in a vapor state. The vapor is then condensed into a liquid by the recovery unit and transferred to the recovery cyclinder.

Vapor Recovery Process
  1. Turn off the HVAC system as well as the recovery machine.
  2. Connect a hose with a low-loss fitting on both ends to the discharge side of the recovery equipment.
  3. Connect the other end of this hose to the tank liquid port on the recovery cylinder.
  4. Place the recovery cylinder on a scale.
  5. Connect a hose from the low-side service port of the air conditioning system.
  6. Connect the other end of this hose to the center (charging) port of your manifold set.
  7. Connect a hose to the low-side of your manifold set.
  8. Connect the other end of this hose to the suction side of the recovery equipment.
  9. Connect a hose from the tank vapor port to the high gauge on the manifold set. This will allow you to monitor the tank pressure.
  10. Close valves on manifold set.
  11. Open vapor and liquid valves on the recovery cylinder.
  12. Start the recovery system.
  13. Allow unit to pull into the appropriate vacuum based on refrigerant type.
  14. Close all valves and disconnect from the air conditioning system or begin purge cycle.

Push-pull Recovery

The push-pull recovery method is used for transferring large volumes of liquid refrigerant. During this process, the recovery unit pulls vapor from the recovery cylinder and produces high pressure discharge gas that pushes liquid out of the HVAC system and back into the recovery cylinder.

You should not use the push-pull method if the air conditioning system contains less than 10 pounds of refrigerant, if the system is a heat pump, or if it is a unit with a reversing valve. In addition, if the system has an accumulator between the service ports used in liquid recovery or if the refrigerant system doesn’t allow for the formation of a solid column of liquid, you should not use the push-pull method.

Extra equipment is needed for this method. Before you get started, you will need an extra hose, a recovery cylinder with no more than 5lbs of refrigerant and a sight glass rated for the pressure of the refrigerant you are using.

Push-pull Recovery Process
  1. Turn off the power to the HVAC system you are servicing.
  2. Connect a hose from the discharge port of the recovery unit to the vapor side of the HVAC system.
  3. Connect another hose from the liquid side of the HVAC system to the sight glass and on to the liquid side of the recovery tank.
  4. Connect a hose from the vapor side of the recovery tank to the suction port of the recovery unit.
  5. Once all connections are hooked up, purge the hoses of non-condensables before starting recovery.
  6. While recovery is in progress, watch the sight glass closely. When the passing liquid is no longer visible through the sight glass or when the scale reading stops going up, the push-pull method of recovery in complete.  


Liquid Recovery Method

With the liquid recovery method, refrigerant is transferred while still in the liquid state. Recovering liquid is ideal for recovering large amounts of refrigerant like refrigerant transfer, or if the system you are servicing will allow you to recover liquid.

Liquid recovery is performed the same way as vapor recovery. The only difference is that you will connect to the high side of the system.

Liquid Recovery Process
  1. Turn off the power to the HVAC system you are servicing.
  2. Also make sure the recovery machine is set to “off” and all valves on the manifold are closed. A manifold is good to use during this method because it has additional metering and allows you to pull from the high and low side ports at the same time.
  3. Now connect a ¼ inch utility hose of your manifold to the suction port of your recovery machine.
  4. Finally, connect a hose from the liquid side of the recovery cylinder to the discharge port.
  5. You will want to be sure that the ends with the shut offs are used at the suction and discharge ports. This is required by law.
  6. Before beginning recovery, purge all hoses of non-condensables.
  7. Open the liquid valve on the recovery tank. DOE regulations require that tanks cannot be filled above 80 percent capacity.
  8. Turn the recovery unit on.
  9. Turn the selector valve on the recovery unit to “liquid.”
  10. Open the high side valve and the utility port on the manifold. The unit will recover until the low pressure switch shuts down the unit and the recovery machine indicates that the recovery is complete.