Regulating device for a heating device

The device (R) has a switching power supply (NT) supplied with a supply voltage (S1). Electronic assemblies are supplied with a secondary sided device low voltage (S2). Regulating and switching devices control, switch on and switch off the electronic components (K1-K3). The supply voltage on a primary side of the supply and the low voltage on the secondary side of the supply are measure and evaluated. The components attached to the device are switched off when measured voltage values of a preset voltage-threshold for the individually attached assemblies and the components are different.