Self-calibrating foil heat flux sensor with thermal spreaders and heater

A next-level sensor from the world market leader in heat flux measurement, FHF04SC is a combination of our standard model FHF04 heat flux sensor and a heater. The heater allows the user to perform self-tests, verifying sensor functionality and stability during use, without having to remove the sensor. FHF04SC is ideal for high-accuracy and long-term heat flux measurement, construction of calorimeters, (zero heat flux) core temperature measurement and thermal conductivity test equipment.

  • Flexible (bending radius ≥ 15 x 10⁻³ m)
  • Low thermal resistance
  • Wide temperature range
  • Fast response time
  • Integrated type T thermocouple
  • Robustness, including metal connection block, may be used as strain relief
  • IP protection class: IP67 (essential for outdoor application)
  • Integrated thermal spreaders for low thermal conductivity dependence


FHF04SC is a sensor for general-purpose heat flux measurement, combined with a heater. It is used when the highest level of quality assurance is required and for long-term heat flux measurement. It is thin, flexible and versatile. FHF04SC measures heat flux through the object in which it is incorporated or on which it is mounted, in W/m². The sensor in FHF04SC is a thermopile. This thermopile measures the temperature difference across FHF04SC’s flexible body. A type T thermocouple is integrated as well. The thermopile and thermocouple are passive sensors; they do not require power.

Multiple small thermal spreaders, which form a conductive layer covering the sensor, help reduce the thermal conductivity dependence of the measurement. With its incorporated spreaders, the sensitivity of FHF04SC is independent of its environment. Many competing sensors do not have thermal spreaders. The passive guard area around the sensor reduces edge effects and is also used for mounting.

Using FHF04SC is easy. It can be connected directly to commonly used data logging systems. The heat flux in W/m² is calculated by dividing the FHF04SC output, a small voltage, by the sensitivity. The sensitivity is provided with FHF04SC on its product certificate. When used under conditions that differ from the calibration reference conditions, the FHF04SC sensitivity to heat flux may be different than stated on its certificate. See the user manual for suggested solutions.

Measuring heat flux, users may wish to regularly check their sensor performance. During use, the film heater is activated to perform a self-test. The heat flux sensor response to the self-test results in a verification of sensor performance.  Implicitly also cable connection, data acquisition, thermal connection of sensor to its environment and data processing are tested. Heat flux sensors are often kept installed for as long as possible. Using self-testing, the user no longer needs to take sensors to the laboratory to verify their stable performance. In a laboratory environment, using a metal heat sink, you may even perform a formal calibration. The heater has a well characterized and traceable surface area and electrical resistance.

Would you like to study energy transport / heat flux in detail?  Order FHF04 with radiation-absorbing black and radiation-reflecting gold stickers. You can then measure convective + radiative flux with one, and convective flux only with the other. Subtract the 2 measurements and you have radiative flux. BLK – GLD stickers can be applied by the user to the sensor. Optionally, they can be ordered pre-applied. See the BLK – GLD sticker series user manual and installation video for instructions.

Suggested Use:

  • high-accuracy scientific measurement of heat flux, with a high level of data quality assurance
  • study of convective heat transfer mechanisms
  • calorimeter prototyping
  • (zero heat flux) non-invasive core temperature measurement
  • thermal conductivity test equipment



  • Building physics / insulation, thermal comfort and energy budget measurement
  • Heat flux measurement to validate CFD thermal simulations
  • Industrial monitoring and control / heat flux and heat transfer measurement
  • Meteorology / surface energy flux measurement
  • Scientific research / heat and heat transfer measurement



  • BLK – GLD sticker series



heat flux, temperature

Measurement range

(-10 to +10) x 10³ W/m²

Sensitivity (nominal)

11 x 10⁻⁶ V/(W/m²)

Temperature sensor

type T thermocouple*

Thermal spreaders


On-line functionality testing

self-test including self-calibration

Rated bending radius

≥ 15 x 10⁻³ m

Rated load cable

≤ 1.6 kg

Outer dimensions foil with guard

(50 x 50) x 10⁻³ m

Sensing area

9 x 10⁻⁴ m²

Sensor thermal resistance

30 x 10⁻⁴ K/(W/m²)

Sensor resistance range

160 to 240 Ω

Sensor thickness

0.7 x 10⁻³ m

Uncertainty of calibration

± 5 % (k = 2)

Rated temperature range - continuous use

-40 to +120 oC**

IP protection class


Standard wire length

2 m

Heater resistance

100 Ω (nominal)

Heater power supply

12 VDC


with 5 m wire length; BLK-5050 black sticker; GLD-5050 gold sticker
* temperature measurement uncertainty: 2 % of value in C. For details, refer to user manual.
** rated operating conditions: 120 ˚C continuous use, 150 ˚C short intervals; use to -80 ˚C is possible.
*** sensor is not suitable for continuous exposure to water.


Download Product Brochure

Download Product Manual

Go to Top