The components of the FLEXIRO sets are carefully dimensioned to match each other in terms of technology. It is very unlikely that the heating pipes will not allow sufficient heating water to pass through if they are installed correctly. If the heating surface does not get warm, please first check whether the Multibox or Kompabox is correctly connected to the flow and return of the heating system. Perhaps only one heating pipe has been kinked. If several heating circuits were installed, one heating pipe may have been disproportionately shortened in length. As a result, the heating circuit with the longest connection pipe may not heat up properly. The pipe lengths of the individual heating circuits should be approximately the same.