Pressurized Hot Water Temperature Control Unit

A pressurized hot water temperature control unit circulates liquid water through a closed circuit at temperatures well above its normal atmospheric boiling point (100 °C).

By integrating heating, cooling, circulation, precision temperature sensing, and automated pressure management into a single closed-loop system, these units deliver stable, high-efficiency thermal transfer for demanding industrial manufacturing processes.

Key Specifications for Technical Selection

When evaluating pressurized water units, do not select by maximum temperature or heater power alone. System performance depends on matching thermal capacity, pump dynamics, and pressure limits to your process circuit.

Specification	Standard Model Example (e.g., PHW-160-18)	Technical Selection Rationale
Max. Operating Temperature	160 °C	Defines the absolute thermal limit of the system.
Temperature Control Range	20 °C to 160 °C	Establishes the usable thermal window for operations.
Heating Capacity	18 kW	Determines heat-up speed and thermal recovery rates.
Pump Flow Rate	60 L/min	Drives heat transfer rate across tool channels.
Pump Pressure	5.5 bar	Overcomes hydraulic resistance in long or narrow circuits.
Operating Pressure Range	6.0 bar to 8.0 bar	Maintains water in liquid state at high temperatures.
Cooling Capacity	45 kW (at ΔT = 40 °C)	Prevents thermal overshoot and shortens cycle times.
Process Connections	3/4" BSP / NPT	Must match main manifold and process line sizes.
Cooling Water Connections	1/2" BSP / NPT	Determines compatibility with facility cooling lines.
Power Supply	380V-415V / 50Hz / 3-Phase	Must match facility electrical supply (Optional: 460V / 60Hz).
Temperature Sensor	Pt100 Class A	Delivers accurate, low-latency feedback control.
Control Method	PID Microprocessor / PLC	Provides precise proportional heating and cooling outputs.
Communication Interface	RS485 (Modbus RTU)	Enables integration with processing machines or plant SCADA.
Dimensions (L x W x H)	980 x 450 x 1050 mm	Required for floor space layout and installation.
Machine Weight	135 kg	Essential for logistics and site floor load planning.

Temperature Classification & Application Guide

120 °C Class: Ideal for standard injection molding, blow molding, and mold preheating applications requiring temperatures slightly above atmospheric boiling.

140 °C Class: Designed for engineering plastics, precision optics, automotive interior components, and complex mold channels with high surface quality demands.

160 °C Class: Engineered for reinforced polymer processing (such as PA66-GF, PBT, or PPS blends), structural automotive tooling, and specialized industrial thermal loops.

180 °C Class: High-specification units requiring verified pressure ratings, high-temperature pump mechanical seals, heavy-duty expansion volumes, and redundant safety relief valves for continuous operation.

System Dynamics: Balancing Heat, Flow, and Pressure

Heating Load (kW): Dictates initial ramp-up time and offsets standing radiant thermal losses.

Pump Flow (L/min): Creates turbulent flow (Reynolds Number > 4000) inside cooling channels, significantly improving overall heat transfer coefficients.

Pump Pressure (bar): Sustains necessary volumetric flow through tight core channels, quick disconnect fittings, and restrictive piping configurations.

Cooling Capacity (kW): Essential for removing exothermic heat or accommodating fast production cycles without thermal runaway.

Comparison: Pressurized Water vs. Thermal Oil

Feature	Pressurized Hot Water Systems	Thermal Oil Systems
Heat Transfer Medium	Treated Water	Synthetic or Mineral Oil
Operating Range	Up to 180 °C	Up to 300 °C and above
Specific Heat Capacity	High (~4.18 kJ/kg·K)	Moderate (~2.0 kJ/kg·K)
Circuit Pressure	Elevated pressurized circuit	Low atmospheric pressure at medium temps
Cleanliness & Environment	Clean, non-contaminating, zero disposal cost	Risk of leaks, smoke, and hazardous fluid disposal
Maintenance	Routine water conditioning and filtration	Regular oil degradation testing and replacement

Integrated Safety Functions

Independent Over-Temperature Protection: Mechanical limit switch that operates independently of the main temperature controller.

Automatic Air Venting & Pressure Relief: Automated purging cycle during startup paired with a certified safety relief valve (PRV).

Low Level & Dry-Run Prevention: Level sensors prevent heater burnouts and pump cavitation damage.

Electrical Safety Monitoring: Includes phase sequence detection, motor overload relays, and emergency stop interlocks.

Quality Control & International Compliance

Hydraulic Pressure Testing: Circuits are pressure tested to 1.5 times working pressure to verify all welds, joints, and seals.

Electrical Safety Inspection: Full testing for insulation resistance, grounding continuity, and functional safety cutouts per industrial standards.

Factory Acceptance Test (FAT): Complete operational test under thermal load conditions to verify heating, cooling, PID responsiveness, and sensor calibration.

Certifications & Standards:
• Pressure Vessels: CE / PED 2014/68/EU compliant pressure components and safety relief valves.
• Electrical Safety: Built in accordance with IEC 60204-1 and UL 508A design standards.
• Quality Management: Manufactured under ISO 9001 certified quality control systems.

FAQ

Q: What water quality is required for a pressurized hot water temperature control unit?

A: Deionised, soft, or treated water with a pH between 7.0 and 8.5 is recommended. Low mineral content prevents scale buildup on heating elements and inside internal pipework, maintaining heat transfer efficiency and extending component lifespan.

Q: Can a pressurized hot water unit replace an existing thermal oil controller?

A: Yes, provided the required process temperature is below 180 °C. Water offers higher specific heat capacity and cleaner operation compared to thermal oil, but the mold or piping circuit must be rated to handle the required loop pressure.

Q: How does the system prevent pump cavitation at high operating temperatures?

A: The unit maintains circuit pressure above the vapor pressure of water at the target temperature. Automated pressure control valves keep the loop fully pressurized, ensuring water remains in a stable liquid state at the pump inlet.

Q: Why is cooling capacity as important as heating capacity in model selection?

A: While heating capacity brings the tool up to operating temperature, cooling capacity removes heat generated during production cycles (such as hot polymer melt in injection molding). Insufficient cooling capacity leads to temperature drift and process instability.

Q: What documentation is provided with the unit for factory compliance reviews?

A: Each unit includes a comprehensive documentation package: General Arrangement (GA) drawings, hydraulic and electrical schematics, operation manuals, factory pressure test certificates, and relevant CE/PED conformity declarations.

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