Bitzer S4G-12.2Y 12HP Two-Stage Condensing Unit

Typical Applications

The S4G-12.2Y is sized for single large cold rooms or small multi-room facilities where one condensing unit serves several evaporators. Typical deployments include frozen food storage rooms between -18°C and -25°C, distribution hubs supplying retail and foodservice chains, blast-chill buffer rooms, and ice cream or seafood storage where evaporation temperatures below -35°C are required. Because two-stage compression handles high pressure ratios efficiently, the unit also fits retrofit projects that replace aging single-stage equipment struggling to hold temperature in hot ambient conditions. For facilities planning future expansion, the unit’s capacity headroom allows additional unit coolers to be connected after an engineering review of line sizing and liquid supply.

Why Two-Stage Compression Matters in Deep Cold Storage

Compressing refrigerant vapor from a -40°C evaporation pressure up to condensing pressure in a single stage creates extreme pressure ratios, high discharge temperatures and reduced efficiency. The S4G-12.2Y avoids these problems by splitting compression into two stages with intermediate cooling. Vapor leaving the low-stage cylinder is cooled before entering the high-stage cylinder, which lowers discharge temperature, protects oil quality and improves the compressor’s volumetric efficiency. The practical result for cold store operators is a unit that pulls down room temperature faster after door openings, recovers quickly from defrost cycles, and consumes less energy per kilowatt of refrigeration at deep temperatures. Where energy cost dominates operating expense, two-stage machines such as the S4G series typically outperform single-stage alternatives over the life of the installation.

Assembly Quality and Project Support

Every Arteco condensing unit is assembled to a documented build specification: torque-checked fasteners, brazed joints inspected under nitrogen purge, and triple pressure testing of the refrigerant circuit. Units ship with electrical connections clearly labeled and with test documentation that supports traceability and insurance requirements. Our engineers assist with unit selection against room loads, refrigerant line sizing, and control configuration, and our U.S. team coordinates spare parts and technical follow-up throughout operation.

Frequently Asked Questions

What size of cold room can a 12 HP two-stage unit serve?

Capacity depends on the target room temperature, product load, door traffic and ambient conditions rather than floor area alone. As a rule of thumb, units in this class serve frozen rooms of roughly 100–300 m³ at -18°C to -25°C. Submit your room dimensions and temperatures through our RFQ form and we will confirm the selection.

Can this unit run on R507A as well as R404A?

Yes. The Bitzer S4G-12.2Y is approved for both R404A and R507A. The two refrigerants have similar operating envelopes, so the unit can be specified for either without changing the mechanical configuration. Our team can advise which refrigerant best matches your project’s compliance and efficiency targets.

Is the unit suitable for serving multiple evaporators?

It is a common configuration. One S4G-12.2Y can feed several unit coolers through properly sized liquid and suction lines with individual expansion valves and solenoid controls. We review the piping layout during selection to ensure even oil return and balanced operation.

What documentation and warranty come with the unit?

Each unit ships with test records, wiring diagram, operating manual and a manufacturer-backed warranty on the Bitzer compressor. Arteco provides start-up guidance and holds spare parts support for the full operating life of the equipment.