Only one hydrocarbon refrigerant has EPA approval specifically for retrofit use: Hydrocarbon Blend B, approved as a substitute for CFC-12 in retrofitted and new industrial process refrigeration systems. Every other hydrocarbon refrigerant on the EPA’s approved list, including propane (R-290), isobutane (R-600a), and R-441A, is approved for new equipment only.
This distinction matters enormously. If you’re looking to drop a hydrocarbon refrigerant into an existing air conditioner, freezer, or commercial cooler, the EPA has not approved that practice, regardless of what you may see marketed online. Here’s what you need to know about the approvals that do exist and why the retrofit question is so restrictive.
Hydrocarbon Blend B: The One Retrofit Approval
Hydrocarbon Blend B is listed under the EPA’s Significant New Alternatives Policy (SNAP) program as an acceptable substitute for CFC-12 in industrial process refrigeration. This is the only hydrocarbon refrigerant with explicit retrofit approval, and it applies to a narrow category: industrial process systems, not household appliances, commercial coolers, or air conditioning units. If your system doesn’t fall into that industrial category, this approval doesn’t apply to you.
What’s Approved for New Equipment
The EPA has approved several hydrocarbon refrigerants for use in new equipment across specific product categories. All of these approvals come with use conditions, and none of them extend to retrofitting existing systems.
- Propane (R-290): Approved for new household refrigerators and freezers, retail food refrigerators and freezers (stand-alone units), vending machines, and self-contained room air conditioners.
- Isobutane (R-600a): Approved for new household refrigerators and freezers, and retail food refrigerators and freezers (stand-alone units).
- R-441A (a hydrocarbon blend): Approved for new household refrigerators and freezers, retail food refrigerators and freezers (stand-alone units), vending machines, and room air conditioners.
The word “new” in every one of these listings is deliberate. These refrigerants are approved only for equipment designed, built, and safety-tested to handle them from the factory floor. Manufacturers engineer specific components, charge limits, electrical safeguards, and ventilation features into new units before they leave the production line.
Why Retrofit Approvals Are So Rare
Hydrocarbon refrigerants like propane and isobutane are classified as A3 refrigerants, meaning they are highly flammable. Systems originally designed for non-flammable refrigerants (classified A1) lack the safety features needed to handle a flammable gas. The electrical components may not be spark-proof. The cabinet or housing may not contain a leak safely. The charge amount may exceed what’s safe for the space.
Current safety standards limit propane charges to 300 grams per refrigeration circuit in retail food applications. That’s roughly 10.5 ounces. Equipment designed from scratch can work within that constraint, but an older system built for a different refrigerant often requires a larger charge to function properly. There’s no simple way to retrofit safety into a system that wasn’t designed around flammability risk.
ASHRAE’s position on refrigerant selection reinforces this caution. The organization recommends that refrigerant decisions consider safety, energy efficiency, environmental impact, and regulatory compliance holistically, rather than optimizing for any single factor like low global warming potential. Their guidance calls for updated standards and guidelines to support safe adoption of lower-GWP refrigerants, including hydrocarbons, but emphasizes that widespread use of flammable refrigerants requires careful consideration of occupant safety and scientifically based codes applicable to all HVAC and refrigeration systems.
The HFC Phase-Down Driving Interest
The reason so many people are searching for hydrocarbon retrofit options right now is the federal HFC phase-down. The American Innovation and Manufacturing (AIM) Act requires the U.S. to cut HFC production and consumption by 85% from baseline levels by 2036. By the end of 2025, annual consumption must be 40% below the baseline of 302.5 million metric tons of CO2 equivalent. The first restrictions on HFC use in new products and systems began on January 1, 2025.
As HFCs become scarcer and more expensive, the pressure to find alternatives grows. Hydrocarbon refrigerants are attractive because they have extremely low global warming potential and strong thermodynamic performance. But the phase-down is designed to push manufacturers toward next-generation equipment, not to encourage field conversions of older systems. The EPA has authority to restrict HFC use sector by sector, and it’s using that authority to accelerate transitions in specific product categories rather than broadly approving flammable drop-in replacements.
What This Means in Practice
If you’re maintaining an older system that currently runs on an HFC like R-134a or R-404A, or an HCFC like R-22, your legal options for hydrocarbon refrigerants are extremely limited. For most residential and commercial applications, no hydrocarbon is approved for retrofit. Hydrocarbon Blend B covers only industrial process refrigeration as a CFC-12 replacement, which rules out the vast majority of situations people encounter.
Products marketed as “drop-in” hydrocarbon replacements for home or commercial systems exist on the market, but using them in equipment not designed for flammable refrigerants creates both safety and legal liability. A leak in a system without spark-proof components and proper ventilation can create fire or explosion risk. Insurance coverage, warranty status, and code compliance can all be affected.
For most people, the practical path forward is to continue servicing existing equipment with its original refrigerant (or an approved non-hydrocarbon substitute) until it reaches end of life, then replace it with new equipment designed for a low-GWP refrigerant. New R-290 refrigerators, freezers, and self-contained coolers are increasingly available and built to meet all the safety requirements that make hydrocarbon use viable.