Underfloor heaters transfer heat by piping systems arranged in a spiral or winding pattern beneath the floor covering. Underfloor heating requires much lower feed flow temperature than conventional radiators. Underfloor heating systems are particularly well suited for use with heating systems that use solar thermal collectors.

Besides its function as a heat sink when used as an underfloor heating system, the HL 320.07 trainer can also be used as a heat source for a heat pump in the HL 320 modular system. In this case, the direction of the heat transport is reversed.

HL 320.07 is equipped with three individually selectable piping systems of different lengths. The pipes are surrounded by a tank which can be filled with water if necessary. Sensors are mounted on the piping system to detect the temperature on the feed and return.

Heat quantities and energy balances can be calculated using these temperatures together with the measurement data from the integrated flow meter.

Carefully structured instructional materials have been created for the intended modular combinations with the HL 320.07 module. As part of the documentation for the HL 320 modular system, these materials set out the basic principles and provide a step-by-step guide through the experiments.