Abstract: The invention relates to a heating system component for a heating system for heating a fluid medium, with a carrier unit, and a heating unit coupled to said carrier unit, and a controller; wherein said carrier unit comprises a wet side and a dry side, wherein said wet side corresponds to a surface of said carrier unit configured to be in contact with said fluid medium, wherein said dry side is located on a surface opposite to said wet side. A temperature sensor, in particular an NTC thermistor, is effectively in thermal contact with at least a part of an upper surface of said dry side of the carrier unit, the method comprising: receiving a starting signal at the controller for starting the heating system component; carrying out a test routine for at least the at least one temperature sensor; and in case the test routine is not successful: entering a safe state of the heating system component.

Abstract: A safety ladder comprises a vertical central ladder stringer and a plurality of horizontal rungs attached thereto, wherein the central ladder stringer has a substantially C-shaped cross section with a front longitudinal slot, a rear transverse piece lying opposite to the longitudinal slot, this rear transverse piece having rounded longitudinal edges. The rungs are attached from the outside to the central ladder stringer and are bent with their free outer members forward. In order to provide a better distribution of the climbing forces without impairing any corrosion protection measures or obstructing the interior of the longitudinal slot, the rungs are provided with a preferably equal sided, trapezoidally shaped recess for the rear transverse piece, by which the rungs sit riderlike on the central ladder stringer contacting only in the vicinity of the longitudinal edges of the ladder stringer and the rungs are attached to the central ladder stringer by a fastening means.