Streamlining the Low-GWP Refrigerant Transition with Smart Tools

As of January 1, 2025, the EPA’s Technology Transitions Program has started to phase in prohibitions on the manufacturing of certain categories of HVAC equipment that use refrigerants with a global warming potential (GWP) over 700.[i] As a result, contractors can expect to see an influx of new equipment using low-GWP refrigerants such as R-454B. Because ASHRAE has categorized these emerging low-GWP refrigerants with an A2L low-flammability classification, contractors will be required to adjust many existing refrigerant usage, storage and transportation protocols.  

One of the most notable changes will require contractors to determine if a refrigerant leak detection system (RDS) is necessary as part of the installation. An RDS is designed to prevent the formation of A2L refrigerant concentrations from reaching defined lower flammability levels (LFL). Per UL-60335-2-40 and ASHRAE 15 & 15.2 standards, RDS requirements are based on refrigerant charge limits and the minimum occupied volume of the room.[ii]  

Piping requirements under A2L refrigerant guidelines will remain similar to legacy refrigerants in many cases. However, it is important to adjust calculations to capture the accurate coefficient. Long-line applications must also consider changes in charge volume. Remaining prudent about refrigerant piping size can enhance both safety and equipment efficiency.

Determining RDS and piping needs are the responsibility of the installing contractor and typically involve manual calculations that can be time-consuming and complex. Recent innovations in smart tools can streamline these processes to help contractors save time and build confidence as they adapt to new A2L refrigerant requirements.  

Emerging RDS calculators

Many manufacturers will not design equipment with a default RDS in place since an RDS isn’t required for all applications. Instead, the installing contractor must determine if an RDS should be specified based on the parameters of each unique application, including refrigerant volume, supply air discharge height, total area being conditioned and potential individual zone impact of their exact application. Some states and municipalities may have additional requirements. The Air Conditioning, Heating and Refrigeration Institute (AHRI) maintains an interactive map detailing state and local building codes related to A2L regulations which can help contractors keep track of codes, especially those working across state lines. 

Between application calculations and varying localized standards, determining if an RDS is required can leave contractors and distributors with a hefty workload piled on top of the traditional equipment installation process. Smart tools such as the Johnson Controls RDS Calculator are helping streamline the process by providing simplified prompts to speed up calculations and straight forward recommendations to ensure compliance.        

As part of the Johnson Controls Ducted Systems Solutions app, the free RDS calculator can help contractors quickly and efficiently determine if an RDS is recommended. Contractors on the jobsite can enter their application criteria including refrigerant volume, supply air discharge height, total area being conditioned and potential individual zone impact to generate an immediate report detailing RDS requirements. The report includes easy to understand rationale and flags additional mitigation recommendations such as whether additional exhaust air is required. From there, contractors can also use the app to find equipment information, step-by-step installation guides and troubleshooting resources. 

Refrigerant piping smart tools

Although many A2L refrigerants, including R-454B, have temperature and pressure characteristics similar to legacy R-410A refrigerants, piping calculations must be adjusted to ensure the correct coefficient is utilized. Long-line applications must also consider how increases in A2L refrigerant charge will impact ventilation and RDS requirements. 

Appropriately sized refrigerant piping is critical to minimizing pressure drops and maximize system reliability and efficiency. In general, oversized liquid lines increase the amount of refrigerant within the HVAC system creating potential compressor reliability issues. Oversized suction lines can create refrigerant velocities that are too low to provide adequate oil return. Under-sizing either the liquid or suction line can result in losses to both capacity and efficiency. 

Digital refrigerant piping calculators can help contractors determine the appropriate diameter of pipes required to ensure the safe and efficient distribution of refrigerant. Design conditions such as compressor tonnage and location, elevation, refrigerant temperature and weight and system layout are input into the tool to determine application-specific recommendations. A report can then be produced detailing pressure drop due to friction and fluid velocity and optimal pipe diameter. In long-line applications, the tool can also provide guidance on mechanical accessories, metering devices and charge requirements. Ensuring these calculations are accurate enables contractors to safely balance system efficiency and costs. 

Preparing for change now, and in the future

Digital tools such as RDS and refrigerant piping calculators provide a straight-forward resource to help contractors save time on the jobsite and ensure accurate calculations are made. Equipment manufacturer’s apps provide quick access to product information, start-up guides and trouble-shooting support. As the HVACR industry continues to advance at a rapid rate, contractors who regularly evaluate and maintain their installation and service toolkits as standards evolve will be poised for success. Many R-410A handheld tools will remain compatible with equipment using A2Ls, but tools must be spark-free and specifically listed with a certified safety agency to ensure compliance. Additionally, it is also important to stay informed on local and state building codes as well as future developments in the HFC phasedown. Staying proactive with the right tools, up-to-date knowledge and compliance measures will help ensure contractors can confidently navigate the future of HVACR.