R22, also known as HCFC-22, is a hydrochlorofluorocarbon (HCFC) refrigerant that was commonly used in air conditioning and refrigeration systems. However, due to its ozone depletion potential, R22 has been phased out in many countries and is being replaced with more environmentally friendly refrigerants.
What is R22?
R22 is a chlorodifluoromethane (CHClF2) compound composed of chlorine, fluorine, and carbon. Some key facts about R22:
- Colorless, odorless gas in its pure form
- Classified as a hydrochlorofluorocarbon (HCFC)
- Has an ozone depletion potential (ODP) of 0.05
- Has a global warming potential (GWP) of 1810
- Non-flammable and non-toxic
- Used as a refrigerant in HVAC and refrigeration systems
R22 was commonly used as a replacement for earlier refrigerants like R12 (CFC-12) that had higher ozone depletion potential. However, due to its chlorine content, R22 still contributes to ozone depletion. It has been phased out in developed countries under the Montreal Protocol, though it is still used in some developing nations.
Does R22 degrade over time?
Yes, R22 does naturally degrade over time, mostly when exposed to high temperatures. The degradation occurs due to the breakdown of the chemical bonds holding the R22 molecule together. There are a few factors that affect the rate of degradation of R22:
- Temperature – Higher temperatures accelerate the degradation process. R22 tends to degrade faster in hotter climates.
- Moisture – Water moisture causes the R22 molecule to break down faster.
- Contamination – Contact with contaminants like compressor oil can lead to chemical reactions breaking down R22.
- Corrosion – Corrosion inside AC systems produces reactive byproducts that degrade R22.
- Leakage – Leakage allows R22 to escape and moisture to enter, speeding degradation.
- Usage – Frequent cycling and use of the AC system degrades R22 over time.
The most common factors affecting real-world R22 degradation are high ambient temperatures, moisture, leakage, and general wear and tear on AC equipment. Older AC systems tend to have higher leakage rates and moisture accumulation, accelerating refrigerant breakdown.
What chemicals is R22 broken down into?
As R22 degrades, the chlorodifluoromethane molecule breaks down into its component elements and a range of chemical byproducts, including:
- Hydrochloric acid (HCl)
- Hydrofluoric acid (HF)
- Formaldehyde (CH2O)
- Chlorine gas (Cl2)
- Hydrogen chloride (HCl)
- Phosgene (COCl2)
- Carbon dioxide (CO2)
- Carbon monoxide (CO)
- Hydrogen fluoride (HF)
Many of these breakdown chemicals are corrosive or toxic at high concentrations, like hydrochloric and hydrofluoric acid. The release of these chemicals into the refrigeration system can accelerate damage and corrosion of components. Refrigerantleak detectors include sensors to detect hydrochloric and hydrofluoric acid byproducts.
Effects of R22 degradation
The degradation of R22 refrigerant over time has several negative effects on air conditioning performance and equipment life:
- Reduced cooling capacity – As R22 degrades, less refrigerant circulates, reducing heat transfer and cooling capacity.
- Increased operating pressures – Breakdown chemicals increase head pressure in the AC system.
- Lower efficiency – More energy is required to maintain cooling as degraded refrigerant circulates.
- Compressor wear – Contaminants and degradation byproducts cause increased compressor wear.
- Corrosion – Chemicals like hydrochloric acid corrode AC components and piping.
- Costs – More repairs and faster refrigerant top-offs are needed.
At advanced stages of degradation, the reduced cooling capacity, lowered efficiency, and increased wear on the compressor can lead to complete AC system breakdown. Poor indoor air quality is also a risk if contaminants enter the air handler.
How fast does R22 degrade?
The rate of R22 degradation depends on the conditions it is subjected to. Under normal conditions in a sealed, maintained HVAC system, degradation is very slow. However, with contributing factors like leaks, high heat, moisture and contamination, degradation can accelerate:
| Condition | Degradation Rate |
|---|---|
| Sealed system, normal use | Less than 5% per year |
| Minor leak, moderate moisture | 5-10% per year |
| Major leak, high moisture | 10-20% per year |
| Very high heat, contaminated system | 20%+ per year |
With multiple accelerating factors like leaks, moisture, and high ambient heat, degradation can be up to 20% annually. In poorly maintained systems and very hot climates, degradation can exceed 20% per year.
Can degraded R22 be reclaimed or purified?
Unfortunately degraded R22 cannot be fully reclaimed or purified back to new refrigerant standards. Chemical breakdown of the R22 molecules cannot be reversed. However, recycled R22 refrigerant can have certain contaminants filtered out before being reused:
- Moisture removal – Drying and filtration can remove moisture from mildly degraded R22.
- Acid removal – Chemical processes can neutralize acids from breakdown.
- Filtering – Particulates and residues can be filtered out.
However, refrigerant reclamation cannot remove all degradation byproducts or replace the depleted R22 molecules. Once R22 chemically breaks down, the process is irreversible. The cooling capacity will remain reduced. Reclaimed R22 may only be suitable as a temporary top-off in older AC systems, not as new unused refrigerant.
Options to replace degraded R22
As R22 degrades beyond usability in an older AC system, the best option is to replace it with a newer, more environmentally friendly refrigerant. Some replacement options include:
- R407C – Short-term R22 replacement, but also being phased out.
- R410A – Long-term R22 replacement, used in most new AC systems.
- R32 – Lower global warming potential than R410a.
- R290 – Hydrocarbon refrigerant praised for low environmental impact.
Technicians may also recommend fully replacing the AC system at the same time as the refrigerant replacement, since the new refrigerant often requires system component upgrades to work optimally.
Is it illegal to release R22 into the atmosphere?
Yes, it is illegal to knowingly vent or release R22 refrigerant from AC systems into the atmosphere. R22 is designated as a ozone-depleting substance banned from release under the Clean Air Act in the USA, and regulated under the Montreal Protocol internationally.
It is also illegal to top off leaking R22 systems with new refrigerant instead of repairing leaks. Substantial fines up to $37,500 per day can be charged for knowingly venting ozone-depleting substances like R22. Proper refrigerant capture and disposal is required.
In some jurisdictions, building owners may also be liable if their property maintenance results in R22 releases due to neglect of AC equipment. Use of unlicensed technicians to service R22 systems also risks environmental release fines if they improperly handle the refrigerant.
Best practices for R22 maintenance
To minimize R22 degradation and extend system life, HVAC technicians recommend these maintenance best practices:
- Perform annual tune-ups to check for leaks, moisture and proper operation.
- Repair identified leaks promptly to avoid moisture intrusion.
- Keep filters, coils and fins clean to maximize airflow and heat transfer.
- Maintain duct sealing to avoid introducing excess moisture.
- Monitor refrigerant pressures and top off charge as needed.
- Replace filter driers/purifiers periodically to remove moisture & acids.
Proactive maintenance helps limit degradation factors and can extend the usable life of an R22 system. However, upgrading to a newer refrigerant technology is encouraged when major repairs are required.
The phaseout and ban on R22
Due to its ozone depletion potential, R22 has been phased out in most developed nations under the Montreal Protocol, an international treaty to protect the ozone layer:
- In the U.S., R22 phaseout began in 2010 and production was banned after 2020 except for servicing existing systems.
- European Union nations banned R22 production in 2015.
- Developing countries like India and China have later phaseout schedules running through 2040.
While R22 use is being phased down, an estimated 57,000 tons remained in existing equipment globally as of 2020. Use and releases from leaks in these systems are still legal to service properly.
However, venting R22 into the atmosphere during maintenance is banned. Technicians must use certified refrigerant recovery equipment to capture R22 for reclamation or destruction. The costs of handling R22 will continue increasing due to these regulations, further encouraging conversion to replacement refrigerants.
Conversion steps when replacing R22
Replacing degraded R22 with a newer refrigerant in HVAC equipment requires several conversion steps:
- Determine the proper R22 replacement based on the system – R407C and R410A are common.
- Recover remaining R22 from the system using specialized equipment.
- Conduct oil analysis to see if oil change is required for the new refrigerant.
- Replace components incompatible with the new refrigerant like filter driers.
- Install replacement refrigerant, check for leaks, and monitor system performance.
A licensed HVAC technician should be consulted to select the optimal replacement refrigerant and conversion process. Extensive system flushing is also advised prior to conversion to remove contaminants. For older R22 systems, full replacement may be the most cost-effective option.
Disposal of degraded R22
Due to environmental regulations, degraded R22 that has been captured from AC systems cannot be vented and must be properly disposed of or destroyed. Typical disposal options include:
- Reclamation – Filtering to remove contaminants for reuse in older equipment.
- Incineration – Burning R22 at high temperatures to break down its molecules.
- Specialized landfills – Depositing intact or crushed R22 cylinders in designated landfills.
The costs of reclamation or destruction can run from $3-$8 per pound, which often exceeds the value of recovered degraded R22. Proper documentation and certification of disposal is mandatory. Technicians that release R22 improperly can face major fines.
Future alternatives as R22 is phased out
As R22 is phased down globally, HVAC manufacturers and refrigerant companies continue developing lower environmental impact alternatives. Some futures alternatives to R22 include:
- Lower global warming potential HFC/HFO blends like R452B and R454B.
- Hyrdrofluoroolefins like R1234yf and R1234ze with no ozone depletion potential.
- Natural refrigerants like CO2, ammonia, and propane (R290) or isobutane (R600a).
- Absorbtion cooling systems using water as the refrigerant.
Many emerging refrigerants have lower global warming impact and zero ozone depletion potential. However, performance testing and equipment upgrades are still required to ensure safe, reliable cooling. The phaseout of R22 continues to drive innovation in more climate-friendly refrigerant technologies.
Conclusion
R22 refrigerant gradually degrades over time, breaking down into less efficient contaminants that can damage AC systems. Factors like heat, moisture, leaks, and contamination accelerate R22 degradation. While degraded R22 cannot be fully restored, replacement refrigerants like R410A and R290 can be safely retrofitted into older R22 systems by qualified technicians. Maintaining R22 systems until new refrigerant upgrades can be implemented is recommended. The global R22 phaseout will continue driving adoption of more sustainable refrigerant technologies with lower climate and ozone impacts.
