Walk-in coolers and freezers

In North America, these systems are widely used in grocery retail, food service, processing, and distribution, where uptime, reliable temperature control, and compliance with U.S. safety, environmental, and refrigerant regulations are critical. 

Danfoss supports walk-in cooler and freezer installations with refrigeration components, refrigerant‑ready solutions, and digital selection tools that help contractors choose compatible products, simplify installation, and plan for low‑GWP and natural refrigerants.   

On this page you can: 

• Understand the main components of a walk-in cooler and freezer system  
• Compare refrigerant-ready solution paths  
• See where Danfoss products fit in a typical installation  
• Use tools to size and select the right components  
• Get answers to common contractor questions 

How a walk-in cooler and freezer refrigeration system works? 

A walk-in cooler and freezer refrigeration system removes heat from an enclosed space to keep products at a stable, controlled temperature. It works by circulating refrigerant through a closed loop of components that compress, condense, expand, and evaporate the refrigerant, while controllers continuously monitor and regulate operating conditions. 

Walk-in systems are designed to run continuously, which makes component compatibility, control logic, and refrigerant choice critical for system performance, energy efficiency, and lifetime. 

Core components in a typical walk-in cooler and freezer refrigeration system

A typical walk-in cooler and freezer refrigeration system includes these main component groups, each with a specific role in reliable operation:

• Condensing unit – provides the refrigeration capacity and rejects heat 
• Compressor – compresses and circulates the refrigerant and is an integrated part of the condensing unit  
• Walk-in cooler and freezer controller – regulates temperature, defrost, alarms, and protection 
• Thermostatic expansion valve (TXV) – controls refrigerant flow into the evaporator 
• Solenoid valve – enables refrigerant control and shut‑off functions (e.g. pump down operation) 
• Filter drier – removes moisture and contaminants to protect the system 
• Evaporator – transfers heat from the room air to the refrigerant 

What matters most when selecting walk-in cooler and freezer components?

Walk-in cooler and freezer refrigeration system components: function and examples

Why system integration matters

In walk-in cooler and freezer applications, reliability depends on how well components work together as a system, not only on individual product performance. Correct matching of compressors, valves, cooler and freezer controllers, and refrigerants helps ensure: 

• Stable room temperatures 
• Efficient operation and lower energy consumption 
• Compliance with refrigerant regulations 
• Longer system lifetime and easier servicing 

Danfoss supports this system‑level approach by offering compatible component portfolios, refrigerant‑ready solutions, and digital selection tools that help contractors design and build walk-in cooler and freezer systems with confidence.

Which walk-in cooler and freezer solution should you choose?

Choosing the right walk-in cooler and freezer solution starts with understanding the application goal, the refrigerant strategy, and the level of control and efficiency required. The guide below helps technicians decide what to start with and what to check next before final selection.

Decision guide: contractor goals vs solution path

When selecting a walk-in solution, technicians typically start with the application type and refrigerant strategy, then confirm component compatibility, control requirements, and efficiency targets before finalizing selection. 

Refrigerant options for walk-in cooler and freezer applications

Walk-in cooler and freezer projects typically choose between A1 retrofit, A2L transition, CO₂, hydrocarbons like propane (R290) where applicable. A2L is used when low-GWP is required with a practical transition path, while CO₂ is chosen for its very low GWP and non-flammability. Hydrocarbons like propane (R290) are another very low GWP potential option when relevant safety aspects and requirements due to their high flammability are taken into consideration.  

Refrigerant choice affects efficiency, regulatory compliance, safety requirements, and long‑term system viability.
This overview helps identify which refrigerant path best fits your cooler and freezer application before you explore detailed solution pages.

Which refrigerant path is right for my walk-in cooler and freezer? 

Most projects follow one of four paths: A1 (legacy/retrofit), A2L (transition), CO₂ (non-flammable and very-low GWP), or R290 propane (where applicable for self-contained/compact systems). Your best fit depends on whether you are retrofitting or planning for new, very low GWP refrigeration system installations. 

When should I choose CO₂ (R744) for a walk-in cooler and freezer? 

Choose CO₂ when the project prioritizes a non-flammable pathway and very low GWP. CO₂ systems operate at significantly higher pressures than traditional HFC systems, requiring components and designs suited for high-pressure applications, so component selection and system design differ from many legacy systems. 

Best fit for: Commercial walk-in cooler and freezers prioritizing non-flammability and long‑term sustainability targets.

Use CO₂ when you need: 

• Very low GWP 
• A non-flammablility pathway 
• Solutions aligned with future regulatory and sustainability strategies 

If you choose CO₂ refrigerant

The resources below help you answer questions such as: 

• Is CO₂ suitable for this cold room size and temperature? 
• Which control and valve strategy is required? 
• How do I select components for high‑pressure operation? 

When should I choose A2L refrigerants for a walk-in cooler and freezer? 

Choose an A2L refrigerant when you need low-GWP than legacy HFC solutions and want a practical transition option for selected cooler and freezer systems. A2L projects typically require planning around component compatibility, charge limits, and safety requirements. 

Best fit for: New systems or selected retrofits that require lower GWP with a practical transition approach. 
 
Use A2L when you need: 

• Lower GWP than legacy HFC solutions 
• A transition path aligned with evolving regulations 
• Compatibility planning across components, charge limits, and safety requirements 

Walk-in coolers and freezers require careful component selection, especially as the industry transitions to A2L low-GWP refrigerants. Important: existing walk-in cooler systems cannot be retrofitted to A2L refrigerants — federal regulations and component incompatibility prohibit this. 

Under current EPA SNAP listings, refrigerant safety requirements depend on the refrigerant selected, charge size, room occupancy, equipment design, and applicable national and local codes. New A2L walk-in cooler installations may require refrigerant leak detection, system shutdown functionality, mechanical ventilation or mitigation measures, alarm notification, and manual reset capabilities in accordance with applicable requirements such as ASHRAE 15 and UL 60335-2-89. The AIM Act is accelerating adoption of lower-GWP refrigerants, making these safety considerations increasingly important during system design and installation.  

Danfoss supports A2L-ready refrigeration systems through solutions including Optyma™ condensing units, AK-CC controllers, Optyma™ Cold Room Controllers, AK-SM 800A System Managers, pressure controls, solenoid valves, and electronic expansion valves that help support system control, monitoring, alarm management, and safe operation.  

If you choose A2L refrigerant 

The resources below help you answer questions such as: 

• Which components require A2L compatibility? 
• What safety requirements and charge limits apply? 
• How do I plan system architecture for A2L refrigerants? 

When should I choose A1 (legacy / non‑flammable retrofit path)? 

Choose an A1 retrofit path when the priority is continuity of an existing system, and a refrigerant change is not feasible in the short term. Plan for future transition if regulations or supply constraints tighten. 

Best fit for: Installed-base continuity and short‑term retrofit practicality. 

Next step: confirm compatibility and plan a staged transition 

When is propane (R290) relevant for walk-in cooler and freezers? 

Choose a propane refrigerant when the project uses compact or self-contained concepts where propane is applicable, and safety requirements can be met. Propane is a hydrocarbon refrigerant with very low GWP, but system design must follow relevant safety requirements and charge considerations. 

Best fit for: Smaller/self-contained solutions where applicable.

Use these documents when you need a deeper reference during system selection, design review, or installation. 

What’s new in the world of walk-in cooler and freezer solutions?

Stay updated on Danfoss product news relevant to:

• superheat control 
• valve developments 
• controller updates 
• refrigerant-ready component ranges

Need help with a walk-in cooler and freezer project? 

Talk to Danfoss if you need support with: 

• component selection 
• refrigerant transition planning 
• control strategy 
• technical documentation 
• product compatibility