The Bitzer Octagon family explained — HE, HES, FE, GE, JE, EES, CES
By DigiEntropy Engineering · 2026-03-07 · 6 min read
Bitzer's Octagon family is the EU reference for semi-hermetic reciprocating compressors. The letter classes (HE, HES, FE, GE, JE, EES, CES) encode bore + stroke + cylinder count. Knowing the system lets you pick the right model from a part number alone.
About this post — Authored by an AI assistant using DigiEntropy's polynomial corpus, the universal compressor predictor, and the project's chart-generation tooling. Charts are produced by Python scripts that read the same database the live site queries; tables and formulas are pulled from the same engineering modules. Findings reflect the project's current dataset and methodology — send corrections or deeper questions to admin@digientropy.com. Bitzer's Octagon family of semi-hermetic reciprocating compressors is the EU reference for commercial + light-industrial refrigeration. From the smallest 2HES to the largest 8GE, the family covers 3 kW to 200 kW per compressor with consistent geometry conventions. The naming system is denser than it looks. "4HE-25Y" tells you, in 5 characters: 4-cylinder, HE-family geometry, 25 capacity index, Y suffix for European voltage option. Knowing the system lets you read a part number like a sentence and immediately understand the compressor. This post is the decoder. The letter classes Each letter class encodes a (bore × stroke) geometry. Across the class, cylinder count scales the displacement; the geometry stays constant. Class Bore × Stroke Capacity range Typical use ------------ HES 30 × 35 mm 1-5 kW Small commercial refrigeration HE 70 × 55 mm 8-40 kW Mid-commercial refrigeration FE 50 × 39 mm 5-25 kW Small-mid commercial GE 82 × 65 mm 30-120 kW Large commercial / industrial JE 50 × 39 mm (V-config) 5-25 kW Compact mid-commercial EES 50 × 39 mm (small-bore) 2-15 kW Small commercial CES 30 × 35 mm (small-bore) 1-8 kW Smallest commercial / heat-pump VES 38 × 39 mm 1-5 kW Very small / residential heat-pump The CES and HES are essentially "Compact" and "Heavy" variants on the same small geometry. The EES is the next size up. The HE and FE families are the workhorses of mid-commercial. GE handles the large-capacity end. Reading a model number Bitzer Octagon part numbers follow this pattern: Examples: - 4HE-25Y: 4 cylinders, HE class, capacity index 25, Y suffix (European 400V 3-phase) - 6FE-50Y: 6 cylinders, FE class, capacity index 50, Y suffix - 2HES-1Y: 2 cylinders, HES class, capacity index 1 (smallest), Y suffix - 8GE-60Y: 8 cylinders, GE class, capacity index 60 (large industrial) Suffixes indicate motor / voltage / accessories variants: - Y: standard European voltage (400V 3-ph 50Hz) - P: low-temperature application package - A: A2L refrigerant qualification - +H: high-temperature heat-pump qualification So 4HE-25Y+H is: 4-cylinder HE class, capacity index 25, European voltage, heat-pump qualified. Why the…