In DX, refrigerant evaporates in the cold-room coil.
In short: it is compact and common for single rooms, but line length, charge, safety and regulation limit its use.
Monoblocks and splits can both use DX. Confirm pipe size, lift, oil return, refrigerant and capacity at design conditions.
How DX works
In a DX system the refrigerant itself evaporates inside the cold room's evaporator coil. Room air is blown across the coil, heat flows into the refrigerant, and the now-vaporised refrigerant is drawn back to the compressor. The high-GWP (or flammable) working fluid is therefore piped all the way into the conditioned space.
DX is the default for small and medium walk-ins, and is what almost every plug-in or split condensing unit on the market uses.
Pros and cons
| DX systems | |
|---|---|
| Pros | Simple and widely understood architecture; often a lower capital cost for one room; compact footprint; no intermediate heat-exchange penalty. |
| Cons | Long refrigerant lines on big rooms cause pressure drop and oil-return problems; the entire charge sits in occupied/piped areas, so a leak releases all of it; capacity and line-length limits make multi-room/multi-zone sites awkward; refrigerant choice is now constrained by F-gas caps. |
Typical application
A restaurant walk-in cooler: the evaporator sits inside the CAM-LOCK box, and the condensing unit (compressor + condenser) sits on the roof or an exterior wall. Frequent door openings spike the heat load, and a simple DX system recovers temperature quickly.
For one small or medium room, DX is often a sensible starting point, but it is not automatically the best answer. Check line length, height difference, condenser conditions, permitted refrigerant charge, safety requirements and service availability. Do not assume that a given equipment type must use R-290 or an HFO: the equipment category, placing-on-the-market date, safety assessment and exact model documentation decide what is permitted.
The catalogue Frostbox cold rooms pair with Daikin condensing-unit families (e.g. GS, SP-O, DB-O). The refrigerant per family is version- and market-dependent — always confirm against the specific datasheet.
Related articles
- Cold room refrigeration systems: an overview
- Secondary-loop (indirect) cold room systems
- Natural refrigerants: CO₂, ammonia, hydrocarbons
- F-gas rules and refrigerant selection
- Choosing the right system for your cold room
Not sure if DX suits your room? Contact [email protected].
