The Hillesheim HTI 16 is an integral resistive sensorless temperature controller purpose-built for electric trace heating systems, flexible heating hoses, and surface heating elements. Instead of relying on a separate thermocouple or RTD sensor, it continuously measures the electrical resistance of the heating wire itself—a special nickel alloy whose resistance changes linearly with temperature. This patented approach transforms the entire heating conductor into a distributed temperature sensor, providing a true average temperature reading over the full heated length or surface rather than a single point value.

How Resistive Sensorless Control Works — and Why It Matters

• The Heating Wire as Its Own Sensor: The HTI 16 constantly monitors the resistance of the connected heating conductor. Because the nickel-alloy heating wire has a precisely known temperature coefficient of resistance, the controller calculates the instantaneous average temperature directly from Ohm's law—no external probe, no separate sensor cable, no additional penetration into the pipe or vessel.
• Full-Length Average, Not a Single Hot Spot: Conventional sensor-based control measures temperature only at the sensor's location. If a pipe has a cold spot 50 meters from the sensor, the controller never knows. The HTI 16 averages across the entire heating circuit, detecting cold zones and hot zones simultaneously and responding immediately—a critical advantage for long pipeline trace heating, tank wall heating, and large-area heating plates where temperature gradients are unavoidable.
• Zero-Delay Response: Because the heating wire itself is the sensing element, any temperature change anywhere along its length is registered electrically within milliseconds. There is no thermal lag waiting for a separate sensor body to equilibrate with its surroundings.

4-Segment Preset Control Ranges — Quick Configuration

• Covering -20 to +250 °C: The controller divides its full operating range into four factory-preset blocks: -20 to +40 °C for frost protection and ambient heating, 0 to 100 °C for standard process heating, 10 to 150 °C for high-temperature processes, and 10 to 250 °C for extreme-temperature applications such as heating of heavy fuel oil lines or high-temperature reactor vessels.
• Simple Digital Setting: Temperature setpoint and segment selection are performed via front-panel keys with confirmation on the 3-digit LED display. No PC, no software, no proprietary programming tool required.
• Flexible System Matching: The calibration curve for the specific heating system is stored digitally in the controller. If the heating element is changed or the controller is moved to a different circuit, a one-touch recalibration sequence re-learns the resistance-temperature characteristic of the new load.

Triac Pulse-Package Power Control & 16 A Output

• Wear-Free Triac Switching: A Triac (bidirectional thyristor) power stage replaces mechanical relays, providing completely silent, arc-free switching with no contact wear. The control algorithm uses pulse-package modulation with zero-crossing detection, which switches only at the AC voltage zero point—eliminating electromagnetic interference and extending heater life by avoiding sharp current transients.
• Direct 3680 W Drive Capability: With a maximum output of 16 A resistive load at 230 V AC (ED 70–80%), the HTI 16 can directly switch heating circuits up to 3680 W without an external contactor or SSR. An independent 6 A changeover relay provides a dry contact for alarm signalling, fan control, or cascade triggering of additional heating zones.

Factory Calibration & One-Touch Matching

• Plug-and-Play Ready: When ordered together with a Hillesheim heating system, the HTI 16 arrives factory-calibrated to that specific heating circuit. Both the controller and the heating system are labelled with matching identification, enabling immediate installation and operation without on-site configuration.
• One-Touch Recalibration: If the controller needs to be reassigned to a different heating circuit, the matching process is executed by a single button press. The controller energises the heating wire, measures its cold resistance and the resistance rise over a defined calibration cycle, and stores the new temperature-resistance curve as an active mode.

HTP 16 Option: Redundant PT100 Monitoring

• Dual-Loop Safety: The HTP 16 variant adds a second independent control circuit with a PT100 sensor input, operating alongside the resistive sensorless main loop. This enables controller-monitor combinations where the PT100 serves as a safety temperature limiter, redundant verification channel, or independent second zone controller—all within the same IP65 housing.

Applications

• Electric trace heating of pipelines, flanges, and valves in chemical, petrochemical, and food processing plants
• Tank and vessel wall heating for temperature-sensitive liquids (oils, resins, syrups)
• Mobile heating/cooling tables (HA-HT series) for automotive forming, bookbinding, plastics processing, and wood-paper industries—the HTI 16's signal relay manages an optional customer-supplied cooling circuit for accelerated cooling cycles
• Frost protection and condensation prevention on outdoor equipment and instrumentation