Drop-in refrigerants: The misunderstood term of the refrigeration industry

The term drop-in refrigerant is widely used across the refrigeration industry, but it's also one of the most misunderstood. While the idea of replacing one refrigerant with another without making any system changes sounds appealing, the reality is often more complex. Before recommending a refrigerant replacement, it's important to understand what's involved and whether a retrofit may be required. 

What is a drop-in refrigerant? 

A drop-in refrigerant is generally understood to be a replacement refrigerant that can be installed into an existing system without modifying components, changing operating settings or carrying out additional system adjustments. The concept gained traction during the initial refrigerant phase-down period, when the industry was looking for simple, cost-effective alternatives to phased-out refrigerants. The ideal scenario was straightforward: recover the existing refrigerant, charge the replacement refrigerant and return the system to operation. But, it turns out it was just that – an ideal scenario, not a realistic one.  

Do true drop-in refrigerants exist? 

In practice, very few refrigerant replacements are truly "drop-in". Modern refrigerant options, particularly HFO and HFO blend refrigerants, often require changes to system settings, performance assessments or component compatibility checks. As a result, all refrigerant changes should be viewed as retrofits rather than drop-in replacements. This distinction is important because even small differences in refrigerant properties can affect system capacity, efficiency, oil return and compressor reliability. 

How to decide between a retrofit and a replacement  

Before recommending a refrigerant change, consider the expected service life of the equipment. In some cases, retrofitting an existing system can extend its useful life while reducing environmental impact. In others, replacing the equipment may deliver better long-term performance, reliability and energy efficiency. The best choice depends on factors including:

• Age and condition of the system

• Equipment compatibility

• Performance expectations

• Operating costs

• Future refrigerant availability 
  

What should you check before retrofitting a refrigerant? 

If a retrofit is determined to be the most suitable option, several key factors should be assessed before proceeding.

Is the refrigerant safety classification compatible?  
The replacement refrigerant should maintain the same safety classification as the original refrigerant wherever possible. For example:

• A1 refrigerants should be replaced with A1 alternatives

• Flammability classifications must be considered carefully

Changing refrigerant safety classifications may introduce additional compliance, safety and installation requirements. 

Will the system capacity remain suitable? 
The replacement refrigerant should provide refrigeration capacity as close as possible to the original system design. Significant capacity differences can affect:

• Product temperatures

• Pull-down performance

• Equipment efficiency

• System reliability 
  

What impact will it have on compressor discharge temperatures? 
High discharge temperatures can reduce compressor life and negatively affect reliability. Before selecting a replacement refrigerant, check that discharge temperatures will remain within acceptable operating limits for the compressor.

Are the seals and elastomers compatible? 
Gaskets, seals and elastomer components must be compatible with both the replacement refrigerant and the lubricant being used. Compatibility issues can lead to:

• Refrigerant leaks

• Seal degradation

• Reduced system reliability 
  

Will an oil change be required? 
Oil return remains critical for compressor lubrication and long-term performance. As a general guide:

• HFC to HFC/HFO blend retrofits do not usually require an oil change

• HCFC to HFC or HFC/HFO blend retrofits require an oil change POE

Always verify lubricant compatibility before completing a retrofit.

Is the expansion device suitable? 
Expansion devices should be evaluated as part of any refrigerant retrofit. Consider:

• Existing TX valve suitability

• Capillary tube performance

• Required superheat adjustments

• Check TXV manufacturers recommendation

Capillary tube systems usually require an upgrade to a thermostatic expansion valve (TX valve), allowing superheat to be adjusted correctly for the replacement refrigerant. 

Can a refrigerant retrofit improve efficiency? 
In some applications, a refrigerant retrofit presents an opportunity to improve system efficiency. For example, upgrading from a traditional TX valve to an electronic expansion valve (EEV), combined with floating condensing pressure strategies, can help offset refrigeration capacity losses while improving overall energy performance.  

The bottom line 

While the term drop-in refrigerant remains common industry language, the reality is there is no refrigerant offering of this nature. Most modern refrigerant replacements are better described as retrofits. Taking the time to assess safety classification, capacity, oil compatibility, expansion device suitability and overall system condition can help ensure a successful outcome for both contractors and customers.

Need advice on refrigerant replacements or retrofit solutions? Speak to your local ACTROL team or explore our refrigerant range and technical resources.