I. Positioning
The PHDG Series is Hitachi's standard heat pump high-speed DC inverter scroll compressor product line, optimized specifically for heat pump heating and low-temperature heating applications. This series covers six capacity grades: AA50PHDG, AA55PHDG, DA65PHDG, DC65PHDG, DC80PHDG, and DD94PHDG. All models use R410A refrigerant and a three-phase power supply of 380-415V/50Hz (compatible with 440V/60Hz).
| Feature Dimension | Description |
| Power Range | 7 HP – 20 HP |
| Refrigerant | R410A |
| Power Supply | 3φ, 380-415V/50Hz, 440V/60Hz |
| Application Condition | Heat pump heating, low-temperature heating |
| Core Positioning | Heat pump dedicated, powerful low-temperature heating |
II. Full Series Parameter Comparison Table
| No. | Model | Nominal HP | Displacement (cm³/rev) | Heating Capacity (kW) | Cooling Capacity (kW) | COP | Type |
| 1 | AA50PHDG-D1S2 | 10 | 50 | 21.53 | 16.48 | 4.2 (Heating) | DC Inverter |
| 2 | AA55PHDG-D1K2 | 10 | 55 | 23.02 | 17.54 | 4.2 (Heating) | DC Inverter |
| 3 | DA65PHDG-D1Y2 | 7 | 65 | 18.75 | — | 3.37 | Fixed-Speed |
| 4 | DC65PHDG-D1J2 | 14 | 65 | 28.28 | 21.4 | 3.25 (Cooling) | DC Inverter |
| 5 | DC80PHDG-D1J2 | 16 | 80 | — | — | — | DC Inverter |
| 6 | DD94PHDG-D1J2 | 20 | 94 | — | — | — | DC Inverter |
Suffix Explanation: S = with Enhanced Vapor Injection (EVI); Y = with integrated oil balance pipe + EVI; J = with integrated oil balance pipe, without EVI; K = without split oil balance pipe and EVI.
III. Detailed Analysis
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Feature: The PHDG Series is equipped with Hitachi's Enhanced Vapor Injection (EVI) technology. Selected models (suffix S/Y) increase refrigerant flow through intermediate vapor injection, significantly boosting heating capacity under low-temperature conditions. The entire series adopts a high-pressure shell design, non-contact oil film sealing, and high-reliability bearings. DA65PHDG-D1Y2 is a fixed-speed type; all others are DC inverter types with a rotational speed range of 10–130 rps.
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Advantage: This series centers on powerful low-temperature heating as its core advantage. The AA55PHDG-D1K2 delivers a heating capacity of 23.02 kW with a heating COP of up to 4.2, meaning every 1 kW of electricity consumed produces 4.2 kW of heat. The DC65PHDG-D1J2 achieves a heating capacity of 28.28 kW with a heating COP of 4.3, a cooling capacity of 21.4 kW, and a cooling COP of 3.25. EVI technology extends the heating range to below -25°C, ensuring stable operation even in severely cold regions. Multiple suffix configurations (S/Y/J/K) meet diverse system design requirements.
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Benefit: For heat pump heating and hot water system manufacturers, the EVI technology of the PHDG Series enables systems to provide stable heating in cold climates, serving as an alternative to traditional coal-fired boilers and electric heaters. For northern Coal-to-Electricity projects, the heating capability below -25°C ensures reliable operation in extremely cold areas. For contractors, the rich suffix configurations (EVI / oil balance / EVI+oil balance) allow the compressor to precisely match different system designs. For end users, a heating COP of 4.2–4.3 means operating electricity costs are only about 1/4 of electric heating solutions.
IV. Quick Selection Guide by Application Scenario
| Application Scenario | Recommended Model | HP | Key Advantage |
| 10 HP Heat Pump Heating | AA50PHDG-D1S2 | 10 | Heating 21.53 kW, COP 4.2 |
| 10 HP Heat Pump (High Heating) | AA55PHDG-D1K2 | 10 | Heating 23.02 kW, COP 4.2 |
| 7 HP Low-Temp Heat Pump (Fixed-Speed) | DA65PHDG-D1Y2 | 7 | Heating 18.75 kW, COP 3.37 |
| 14 HP Heat Pump Heating | DC65PHDG-D1J2 | 14 | Heating 28.28 kW, COP 4.3 |
| 16 HP Large Heat Pump | DC80PHDG-D1J2 | 16 | Large capacity, EVI |
| 20 HP Large Heat Pump Project | DD94PHDG-D1J2 | 20 | 94 cc ultra-large displacement |
Selection Mnemonic: For 10 HP, choose AA50/AA55; for 7 HP fixed-speed, choose DA65; for 14 HP, choose DC65; for 16 HP, choose DC80; for 20 HP, choose DD94. Need EVI? Select suffix S. Need oil balance? Select suffix J/Y.
V. Frequently Asked Questions (FAQ)
Q1: What are the heating capacity and COP of AA55PHDG-D1K2?
AA55PHDG-D1K2 is a 10 HP DC inverter heat pump compressor with a displacement of 55 cm³/rev, heating capacity of 23.02 kW, cooling capacity of 17.54 kW, and heating COP of up to 4.2.
Q2: What are the technical specifications of DC65PHDG-D1J2?
DC65PHDG-D1J2 is a 14 HP DC inverter compressor with a displacement of 65 cm³/rev, cooling capacity of 21.4 kW, heating capacity of 28.28 kW, cooling COP of 3.25, and heating COP of 4.3. Suffix "J" indicates integrated oil balance pipe without EVI.
Q3: What do the suffixes in the PHDG Series represent?
According to Hitachi's model naming rules: S = with Enhanced Vapor Injection (EVI); Y = with integrated oil balance pipe + EVI; J = with integrated oil balance pipe, without EVI; K = without split oil balance pipe and EVI (base version).
Q4: Is DA65PHDG-D1Y2 fixed-speed or inverter?
DA65PHDG-D1Y2 is a fixed-speed low-temperature heat pump compressor, rated at 7 HP, with a displacement of 65 cm³/rev, heating capacity of 18.75 kW, and COP of 3.37.
V. Frequently Asked Questions (FAQ)
