With the Testo 0614 1635 Surface Probe for U-Value Measurement, in combination with a compatible Testo measuring instrument and a further temperature probe, the thermal conductivity coefficient can be determined. The U-value (formerly k-value) is the most important value used to rate the energy efficiency of building components. With the Testo 635 instrument, measuring this value has never been easier. Three temperature values are needed to determine the U-value: outer temperature, surface temperature of inner wall as well as indoor air temperature.

Using Testo's new wireless probes, the outer temperature can be quickly and easily measured with the window closed. The probe is simply positioned outside and transmits readings by radio to the measuring instrument in the room.

With the new patented 0614 1635 U-value probe, the two other temperatures required are measured using one probe. To measure surface temperature, three wires from the U-value probe are attached to the inner wall using modelling clay. The air temperature is measured by a sensor on the probe plug. As soon as the three temperatures required are transmitted to the Testo 635, the instrument calculates the U-value and displays it immediately.