FPDW Series DC Brushless Large Temperature Differential Fan Coil Unit — Stainless Steel Coil Tube Assembly

1. Product Overview

The FPDW Series DC Brushless Large Temperature Differential Fan Coil Unit (Fan Coil Unit, FCU) is a high-efficiency hydronic air-handling terminal unit manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This product integrates a precision-engineered stainless steel coil tube (盘管, Coil Tube) heat exchanger with a direct-current brushless (DCBL) motor-driven fan system, designed to deliver superior thermal performance, energy efficiency, and extended service life in commercial and industrial HVAC (Heating, Ventilation, and Air Conditioning) applications.

The core differentiator of the FPDW series lies in its Large Temperature Differential (ΔT) design philosophy, which enables the unit to achieve a greater temperature drop across the coil per pass of circulating fluid, thereby reducing volumetric flow requirements and associated pumping energy consumption by up to 30% compared to conventional FCU designs.

2. Material & Properties

2.1 Coil Tube Material

The heat exchanger coil tube is fabricated from high-grade austenitic stainless steel, conforming to the following material specifications:

• Primary Alloy Grade: SUS304 / AISI 304 (UNS S30400), composed of 18% Chromium (Cr) and 8% Nickel (Ni) with trace Manganese (Mn) and Silicon (Si)
• Alternative Grade (Marine/Corrosive Environments): SUS316L / AISI 316L (UNS S31603), containing 2–3% Molybdenum (Mo) for enhanced resistance to pitting and crevice corrosion
• Tube Diameter: 8.0 mm (Φ8 mm) outer diameter (OD) with 1.0 mm wall thickness (WT), providing a wall-to-diameter ratio optimized for mechanical integrity and thermal conductivity
• Corrugated Fin Material: High-purity Aluminum (Al) 1060 or 3003 alloy, with a fin thickness of 0.10–0.15 mm and fin pitch of 2.0–2.5 mm

2.2 Mechanical & Physical Properties of SUS304 Coil Tube

• Tensile Strength: ≥ 520 MPa (75,000 psi)
• Yield Strength: ≥ 205 MPa (29,700 psi)
• Thermal Conductivity: 16.3 W/(m·K) at 20°C
• Density: 7,930 kg/m³
• Maximum Operating Temperature: 870°C (short-term); continuous service rated up to 500°C
• Corrosion Resistance: Excellent resistance to atmospheric corrosion, dilute acids, alkalis, and organic/inorganic chemicals

2.3 Fan Motor Characteristics

• Motor Type: Direct Current Brushless (DCBL) Permanent Magnet Synchronous Motor (PMSM)
• Voltage Rating: 24V DC / 48V DC (configurable)
• Speed Control: Multi-speed (3–5 speeds) or PWM (Pulse Width Modulation) variable speed
• Energy Efficiency: IE4 / IE5 (International Efficiency Class 4/5)
• Operating Noise Level: ≤ 28 dB(A) at low speed (whisper-quiet operation)

3. Technical Specifications

Parameter	Specification	Notes
Product Model	FPDW Series	DC Brushless, Large ΔT
Coil Tube Material	SUS304 / SUS316L Stainless Steel	Φ8 mm OD × 1.0 mm WT
Fin Material	Aluminum 1060 / 3003	0.10–0.15 mm thickness
Fin Pitch	2.0 – 2.5 mm	High-density configuration
Temperature Differential (ΔT)	10 – 15°C (design differential)	Large ΔT design
Cooling Capacity	1.5 – 12.0 kW	Model-dependent
Heating Capacity	1.8 – 14.5 kW	Model-dependent
Water Flow Rate	0.3 – 2.0 L/s	Reduced by 30% vs. standard FCU
Motor Type	DC Brushless (DCBL)	PMSM, IE4/IE5 efficiency
Power Supply	24V DC / 48V DC	Low-voltage safe operation
Speed Settings	3–5 Speeds or PWM Variable	Electronic speed control
Operating Noise	≤ 28 – 45 dB(A)	Speed-dependent
Pressure Drop (Water Side)	≤ 30 kPa	At design flow rate
Pressure Drop (Air Side)	≤ 50 Pa	At rated airflow
Operating Temperature Range	-10°C to +50°C (ambient)	Wider than conventional units
Refrigerant (if applicable)	R410A / R32 / Water (hydronic)	Configuration-dependent
Protection Rating	IPX4	Splash water protection
Warranty	5 Years (coil tube); 3 Years (motor)	Against manufacturing defects

4. Manufacturing Process

4.1 Coil Tube Fabrication

1. Raw Material Inspection: Incoming stainless steel tube stock is verified for chemical composition (via Spectroscopic Analysis) and mechanical properties (tensile testing per ASTM A269/A270 standards).
2. Cutting & Deburring: Tubes are precision-cut to specified lengths using CNC tube-cutting machines, followed by internal and external deburring to eliminate flow-restricting burrs.
3. Tube Bending: Hydraulic or CNC tube bending machines form the serpentine coil layout with precise bend radii (minimum 3× tube OD) to prevent material thinning or ovalization.
4. Fin Insertion: Corrugated aluminum fins are inserted between tube rows using automated fin-insertion equipment, ensuring uniform fin spacing and contact pressure for optimal thermal transfer.
5. Fin-Tube Bonding: A mechanical crimping or brazing process secures the fin-to-tube interface, maximizing the effective heat transfer area and minimizing contact thermal resistance.
6. End Header Assembly: Coil tubes are welded (TIG/GTAW welding per AWS D17.1) to stainless steel or copper headers, forming a sealed hydraulic circuit.

4.2 Quality Control During Manufacturing

1. Pressure Testing: Each coil assembly undergoes hydrostatic pressure testing at 1.5× the maximum operating pressure (typically 600 kPa) for a minimum of 10 minutes to verify leak-tightness.
2. Dimensional Inspection: Coordinate Measuring Machine (CMM) verification of coil geometry, tube alignment, and fin spacing.
3. Visual & Dye Penetrant Testing (PT): Surface inspection of all weld joints per ASTM E165 for weld integrity verification.
4. Performance Testing: Air-side and water-side capacity testing in calibrated test chambers per AHRI 210/240 (Air-Conditioning and Heating, Refrigeration Institute Standard 210/240).

4.3 Final Assembly

1. Coil assembly is integrated into the unit casing with the DCBL fan motor, control electronics, condensate drain pan, and air filter.
2. Electrical connections are verified for correct polarity, insulation resistance (≥ 10 MΩ at 500V DC), and continuity.
3. Final performance verification and functional testing of all speed settings and control interfaces.

5. Applications

5.1 Primary Application Domains

• Commercial Buildings: Office towers, retail centers, hotels, and hospitals requiring precise temperature control with low noise operation.
• Industrial Facilities: Electronics manufacturing cleanrooms, pharmaceutical processing plants, and food processing environments where stainless steel corrosion resistance is critical.
• Residential High-End: Luxury apartments, villas, and penthouses with integrated HVAC systems demanding quiet operation and energy efficiency.
• Marine & Coastal Environments: SUS316L-grade configurations for offshore platforms, marine vessels, and coastal facilities exposed to salt-laden atmospheres.
• Data Centers & Server Rooms: Precision cooling applications requiring stable temperature differentials and reliable long-term operation.
• Renewable Energy Systems: Integration with heat pump systems and district heating networks where large ΔT operation reduces hydraulic energy consumption.

5.2 System Integration

The FPDW series is designed for seamless integration into Variable Refrigerant Flow (VRF), Variable Air Volume (VAV), and hydronic radiant systems. The low-voltage DC control interface (24V/48V DC) is compatible with Building Management Systems (BMS) utilizing Modbus RTU, KNX, or BACnet communication protocols, enabling centralized monitoring and optimization of energy consumption across multi-zone installations.

6. Quality Certifications & Standards Compliance

6.1 International Certifications

• ISO 9001:2015 — Quality Management System certification covering design, manufacturing, and service processes
• ISO 14001:2015 — Environmental Management System certification
• CE Marking — Conformity with European Union directives including the Machinery Directive (2006/42/EC) and Low Voltage Directive (2014/35/EU)
• CQC (China Quality Certification) — Mandatory product certification for HVAC equipment in the Chinese market
• UL 1995 — Underwriters Laboratories safety certification for air-conditioning and heat pumping equipment
• CB Scheme — International certification for low-voltage electrical equipment

6.2 Material & Performance Standards

• ASTM A269/A269M — Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubing for General Applications
• ASTM A270/A270M — Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubes for Boiler, Heat Exchanger, and Similar Heat Transfer Applications
• AHRI 210/240 — Performance rating standard for unitary air-conditioning and air-source heat pump equipment
• EN 15243 — European standard for fan coil units (heating, cooling, and ventilation)
• GB/T 19232 — Chinese National Standard for fan coil units

6.3 Environmental & Sustainability Compliance

• RoHS 2011/65/EU — Restriction of Hazardous Substances compliance (lead, mercury, cadmium, hexavalent chromium, PBB, PBDE free)
• REACH Regulation (EC) No 1907/2006 — Registration, Evaluation, Authorisation and Restriction of Chemicals compliance
• ErP Directive 2009/125/EC — Energy-related Products Directive compliance for energy efficiency labeling
• WEEE Directive 2012/19/EU — Waste Electrical and Electronic Equipment recycling compliance

7. Unique Selling Points (USP)

1. Large Temperature Differential (ΔT) Design: Achieves 10–15°C temperature drop across the coil, reducing required water flow rates by 30% and significantly lowering pumping energy consumption and associated CO₂ emissions.

2. DC Brushless Motor Technology: Eliminates carbon brush wear, extends motor life to 30,000+ hours, and enables precise electronic speed control with IE4/IE5 efficiency class ratings.

3. Premium Stainless Steel Construction: SUS304/SUS316L coil tubes provide exceptional corrosion resistance, eliminating the need for chemical treatment and extending service life to 25+ years under normal operating conditions.

4. Whisper-Quiet Operation: DCBL motor and optimized aerodynamic fan design achieve noise levels as low as 28 dB(A), suitable for noise-sensitive environments including hospitals, libraries, and residential spaces.

5. Low-Voltage Safety: 24V/48V DC operating voltage eliminates electrical shock hazards, simplifying installation and