Understanding Secondary Refrigerants: Applications and Advantages
Written by Ed Rice
As energy efficiency and environmental regulations reshape the HVACR industry, engineers and facility managers are seeking innovative solutions to reduce refrigerant usage, enhance safety, and improve system performance. One increasingly popular approach—especially in industrial and low-temperature applications—is the use of secondary refrigerants.
In this blog post, we’ll explain what secondary refrigerants are, where they’re used, and the key advantages they offer in modern refrigeration system design.
What is a Secondary Refrigerant?
A secondary refrigerant is a fluid that transfers heat from the cooled space or product to a primary refrigeration system, which does the actual cooling using a traditional refrigerant like ammonia (R-717), CO₂ (R-744), or an HFO.
In simple terms, the primary refrigerant cools the secondary refrigerant, and the secondary refrigerant carries that cold energy to where it’s needed—such as a walk-in freezer, blast chiller, or processing line.
Common Secondary Refrigerants:
Brine solutions (e.g., calcium chloride, sodium chloride)
Glycol-water mixtures (propylene glycol, ethylene glycol)
CO₂ in pumped volatile systems
Thermal oil or alcohol-based fluids in specialty applications
Where Are Secondary Refrigerants Used?
Secondary refrigerant systems are commonly used in:
Industrial refrigeration (food processing, beverage plants, cold storage)
Supermarkets and retail refrigeration
Ice rinks and arenas
Pharmaceutical and chemical processing facilities
Large commercial HVAC systems using chilled water loops
These applications benefit from the flexibility, safety, and efficiency secondary loops offer—especially in facilities that need to manage multiple zones or equipment spread across large areas.
Key Advantages of Secondary Refrigerants
1. Reduced Primary Refrigerant Charge
One of the biggest benefits of using a secondary loop system is that it drastically reduces the amount of primary refrigerant (such as ammonia or CO₂) circulating through the facility.
This reduces the risk of leaks or exposure to hazardous refrigerants.
It helps facilities meet or exceed regulatory thresholds for refrigerant safety, such as those set by OSHA and the EPA (PSM & RMP).
Less refrigerant charge also means lower operating costs and reduced environmental impact.
2. Improved Safety and Regulatory Compliance
By isolating the primary refrigerant to a dedicated machine room and circulating a low-hazard secondary fluid throughout the building:
You reduce the number of potential leak points.
Maintenance staff and operators are less exposed to high-pressure or toxic refrigerants.
It's easier to comply with IIAR standards, ASHRAE 15, and local building codes.
This makes secondary refrigerant systems ideal for sensitive applications such as food production, healthcare, and public arenas.
3. More Flexible System Design
Secondary refrigerant systems allow for modular, scalable, and distributed cooling across multiple zones or applications. For example:
One central refrigeration plant can feed multiple coolers, freezers, or processing lines.
Chilled water loops or glycol systems can support variable cooling loads across a facility.
System expansion or modifications can be done without touching the primary refrigerant circuit.
This makes them particularly valuable in large-scale or multi-temperature facilities that evolve over time.
4. Energy Efficiency Potential
Modern secondary refrigerants are designed for:
Low viscosity, which reduces pumping energy.
High heat capacity, allowing efficient heat transfer.
Compatibility with thermal storage systems, where secondary fluids are chilled during off-peak hours and used later.
When designed properly, secondary loop systems can offer comparable or even superior energy performance compared to traditional direct-expansion systems.
5. Easier Maintenance and Servicing
Because the secondary fluid loop operates at lower pressure and is non-toxic, technicians can perform routine maintenance with less risk and fewer regulations compared to handling ammonia or CO₂ directly.
System components like pumps, valves, and coils are easier to isolate and service.
Leaks in the secondary loop don’t pose the same hazards as leaks in high-pressure refrigerant systems.
Real-World Example: Secondary Loop with Ammonia
A food processing plant may use ammonia as the primary refrigerant located in a sealed machine room. That ammonia chills propylene glycol, which is then pumped throughout the facility to supply multiple air handling units, blast cells, and underfloor piping systems.
This design keeps ammonia confined to one area, reducing risk and simplifying maintenance—while still delivering powerful cooling across the plant.
How Northstar Refrigeration Can Help
At Northstar Refrigeration, we design and install high-performance refrigeration systems using both direct and secondary loop architectures.
Our team can help you:
Evaluate whether a secondary refrigerant system is right for your facility
Design an energy-efficient, code-compliant solution tailored to your application
Provide ongoing maintenance and monitoring for long-term reliability
Integrate ammonia, CO₂, or low-GWP refrigerants with the right secondary loop fluid
Contact us at (508) 888-3692 to schedule a system consultation or request a site visit.
Final Thoughts
As the refrigeration industry moves toward safer, more sustainable system designs, secondary refrigerants are becoming a smart, future-ready solution. Whether you're designing a new plant or upgrading an existing facility, a secondary loop can help you improve safety, reduce refrigerant usage, and optimize performance across the board.
Looking to explore secondary refrigerant options for your facility? Let Northstar Refrigeration help you find the right solution.
(508) 888-3692
www.northstarhvacr.com