The HFM1 Heat Flux Meter is a measurement system for analysis of thermal resistance and thermal transmittance of building elements by in-situ measurement. It can be used for measurements according to ISO 9869 and ASTM C1155 / C1046 standards. For ISO 9869 and ASTM C1155 / C1046 standards, the HFM1 is equipped with two Heat Flux Plates (HFP01) as well as two pairs of matched thermistors for differential temperature measurements (four total thermistors).
Thermistor excitation voltage is measured at every measurement interval for increased accuracy, this voltage reading is used in the thermistor scripts to remove errors introduced from possible voltage fluctuations.
The in-situ measurement of thermal resistance, thermal transmittance or U-Values of buildings is often applied in studies of building elements.
The thermal resistance, TR, measurement is based on simultaneous measurement of time averaged heat flux F (using a heat flux sensor) and differential temperature, DeltaT, (two temperature sensors).
TR = DeltaT / F
The ISO and ASTM standards on the subject comment on applicability of the method, on installation and on data analysis.
The HFM1 consists of high accuracy electronics (measurement accuracy up to 1 millivolt) as well as matched thermistor pairs to make a differential temperature measurement with better than 0.5°C accuracy. It also includes HFP01 heat flux plates. HFP01 is the world’s most popular sensor for heat flux measurement through building envelopes.
Heat Flux Meter – for ISO9869 thermal resistivity of building materials. Includes: 2 x HFP01 Heat Flux Plate, 2 x THERM-MICRO-10 Temperature Sensors, 2 x THERM-MICRO-30 Temperature Sensor, 1 x CH24 Power Supply, 1 x HFM1: IP65 rated logger enclosure; stand-alone logging capability to 4GB MicroSD Card; Windows software; IP53 rated breakout board enclosure; user manual.
|Analogue Channels||6 Single Ended (SE) and 2 Differential (channel 1 of 10 total is 2.5V thermistor excitation measurement)|
|Minimum Logging Interval||1 second|
|Delayed Start||Suspend Logging, Customised Intervals|
|Test method||ISO 9869 and ASTM C1155 / C1046|
|Differential temperature (DeltaT)||matched pairs calibrated thermistors, Part Number THERM-MICRO|
|Heat flux sensor||type HFP01|
|Protection: sensors and logger||IP 65|
|Cable length||30m and 10m (Thermistors), 10m (HFP01)|
|Storage capacity||Micro SD card, expandable up to 16GB, 4GB microSD card included.
> 5 years of data.
|Data analysis||to be performed by the user according to ISO and ASTM standards|
|Internal Battery Specifications|
|960mAh Lithium Polymer, 4.20 Volts fully charged|
|External Power Requirements|
|Bus Power||8-30 Volts DC, non-polarised, current draw is 190mA maximum at 17 volts per logger|
|USB Power||5 Volts DC|
|Internal Charge Rate|
|Bus Power||60mA – 200mA Variable internal charge rate, maximum charge rate of 200mA active when the external voltage rises above 16 Volts DC|
|USB Power||100mA fixed charge rate|
|Internal Power Management|
|Fully Charged Battery||4.20 Volts|
|Low Power Mode||3.60 Volts – Instrument ceases to take measurements|
|Discharged Battery||2.90 Volts – Instrument automatically switches off at and below this voltage when no external power connected.|
|CH24 Power Supply is supplied in the HFM1 package.|
|Battery Life varies|