Heaters produced from 1993-2006 were affected by a German law, which stipulated that heat exchangers and exhaust ducts needed to be replaced after ten years. For Truma heaters manufactured and put into operation during this time, the replacement obligation was prolonged to 30 years. For appliances manufactured from 2005 onwards, which bear an E1 mark on the type plate, a replacement obligation is no longer stipulated in the European Heating Appliance Directive.
Further information on the replacement obligation can be found in the Truma Service blog.