Decades ago, scientists established a link between refrigerants and ozone depletion. Back in 1987, the Montreal Protocols went into effect; this agreement, signed by 30 countries, required the capture and control of ozone depleting compounds like CFCs and HCFCs. The technology for refrigerant recovery has changed considerably in the last 30-plus years, so we’re going to discuss the equipment, the process itself and the regulations.
The regulations for how to recover refrigerant were redefined and tightened up a bit with the 1992 Clean Air Act. There’s an allowance for “de minimis” venting, which just means the amount of refrigerant that will inevitably be released in the recovery process. That includes:
- Refrigerant that escapes in the course of HVAC repair or normal operation (EPA does require repair of any substantial leaks)
- Mixtures of nitrogen and R-22 that are used as holding charges or leak test gases
- Small releases of refrigerant that occur while connecting or disconnecting hoses in the course of normal service or maintenance
The Clean Air Act also requires that all refrigerant recovery equipment be certified by an EPA-approved testing body, ensuring that the equipment meets EPA standards. The two certified testing organizations are Underwriters Laboratory and Intertek; any refrigerant recovery unit that has their label is approved for use. If you have questions about the right unit, their websites have information on refrigerant types and refrigerant recovery rates for specific units.
Like with any other piece of HVAC equipment, a refrigerant recovery unit has certain specific features you’ll need to be aware of. And like other equipment, the units have become lighter and more compact and the process has become faster and more user-friendly.
Features and Components
- Large condenser: When the refrigerant can be kept cool enough to condense, this speeds recovery rates, and a bigger condenser enhances both cooling and recovery.
- Large fan: The fan’s function is to keep the compressor cool and maintain airflow past the condenser, which is especially helpful when ambient air temperatures are high.
- Compact size: This is self-explanatory; a compact unit is easier to handle and move.
- Purge feature: Look for a purge design that can be used for multiple refrigerant types and will eliminate any chance of cross-contamination.
- High-pressure refrigerant capability: R-410a is becoming more and more prevalent, and your unit should be able to accommodate the higher pressures of this refrigerant.
- Constant pressure regulator (CPR) valve: This valve controls the flow of refrigerant into the unit and is important to preventing damage from a buildup of liquid in the compressor.
- Oil-free compressor: More reliable and requires less maintenance.
- Warranty: Read warranty coverage carefully and look for more than one year of coverage.
- Serviceability: Make sure that your unit can be serviced easily (in the field, if necessary) and that parts availability won’t be a problem down the road.
Just like with any other HVAC work, safety needs to be a top priority when discharging refrigerant to a recovery unit. Make sure to follow these safety guidelines:
- Wear safety glasses and gloves to guard against debris and the possibility of frostbite.
- Never discharge refrigerant near an open flame; an open flame can quickly oxidize it into phosgene gas, which is fatal if inhaled.
- Be sure that your unit is equipped with an overflow sensor, which will shut down the unit when it reaches 80 percent of capacity.
- If handling high-pressure refrigerants, be sure that the cylinder on your unit is a 400 DOT recovery tank; a 350 DOT tank won’t do. Read the product literature carefully to be sure of this, as the two tanks don’t have any distinctive markings or labeling to distinguish between the two. Remember that tanks need to be recertified on a five-year interval.
- Make sure that your unit’s gauges, lines hoses and fittings are set up to handle high pressure refrigerants.
- Always use an inline filter at the inlet port to trap any slivers or particulates and keep them from entering your recovery equipment.
- Double-check all connections, read the unit’s instruction manual and be absolutely certain of what type of refrigerant you’ll be handling.
The three recovery methods are:
- Vapor recovery (still the most common)
- Push-pull method
- Liquid recovery (which is becoming more common).
Here are the steps involved in the vapor recovery process:
- Place the recovery tank on a scale.
- Connect a hose from the low-side service port on the HVAC system.
- Connect the other end of this hose to the charging port on the manifold set.
- Connect another hose to the low side of your manifold set.
- Take this hose and connect it to the suction side of the recovery unit.
- Connect a hose from the high gauge of the manifold set to the tank vapor port, enabling you to keep an eye on tank pressure.
- Close all valves on the manifold set.
- Open vapor and liquid valves on the recovery cylinder and start the system.
- Allow the unit to start pulling a vacuum, being mindful of the right vacuum specs for the refrigerant you’re working with.
- Close all valves and disconnect from the HVAC system, or begin purge cycle.
Here are the steps involved in the push-pull process:
- Connect a hose from the tank vapor port to the manifold’s center port.
- Connect a hose from the low side of the manifold set to the suction side of the recovery unit.
- Connect a hose from the low-side service port to the discharge side of the recovery unit.
- Connect a hose from the tank liquid valve to the high-side service port.
- Place the tank on a scale.
- Open valves on the recovery cylinder and start the recovery machine.
- Open the low-side valve on the manifold set and start monitoring the scale.
- Once the scale stops picking up weight, switch over to vapor recovery.
NOTE: Push-pull is the preferred recovery method only in select circumstances. It shouldn’t be used if there’s less than ten pounds of refrigerant to handle, if the system will allow a solid column of liquid to form, or if the system is a heat pump or any unit that includes an accumulator. If any of these are the case, vapor recovery would be recommended.
Liquid recovery is performed using the same steps as vapor recovery, except the lines should be connected to the high side of the system. It’s preferred if there are large amounts of refrigerant to handle (as in refrigerant transfer) or if the system is set up for liquid recovery.
With the advent of oil-less compressors and constant pressure regulator valves, liquid recovery is becoming more common. An oil-less compressor will have an internal device to flash off the liquid, and these compressors will only work with liquid in systems that include a CPR valve.
A few tips
Here are some things you’ll need to know to make your refrigerant recovery safer and simpler:
- Use the shortest hoses possible, with low-loss fittings at each end.
- ⅜” hoses are preferred and will make the job go faster.
- When possible, remove valve cores from the system.
- It’s acceptable to use a heat gun in some instances, to get refrigerant to boil off.
- When possible, use liquid recovery methods.
- Remember that vapor recovery is 75-80% of the process. When selecting a machine, look for one with a high vapor recovery rate, and a unit that is also compatible with liquid recovery will speed up the process.
- Never mix or cross-contaminate different refrigerant types in storage or in the field.
- Never fill storage tanks beyond 80% capacity.
Recovering and storing refrigerant isn’t just good for the environment and compliance with the law — it saves money as reclaimed, uncontaminated refrigerant can be reused in other systems.
If you have any questions or would like to consult with our team, we’re here for you. We strive to go above and beyond to service our customers. We dedicate ourselves to fostering close, ongoing relationships in order to help customers grow their business. While offering only the highest-quality HVAC equipment and parts, we can provide you with the advice and expertise you need. Contact Us!
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