De Dietrich 83758798 draught diverter thermostat

This is a De Dietrich draught diverter thermostat, listed under catalogue article 336.805.002 and manufacturer codes 83758798 and 336.805.002. It belongs to the Thermostats category. Parts of this type are mechanical thermostats that respond to temperature changes in the draught diverter – the component of the flue system that prevents downdraught and maintains stable combustion conditions. Unlike NTC sensors, which report temperature values to the control board, a draught diverter thermostat acts as a direct switching device: it opens or closes a circuit when the sensed temperature reaches its set point, typically as a safety limit to prevent overheating or to confirm that the flue is not blocked. When selecting a replacement for such a thermostat, attention must be paid to the switching point (the temperature at which it opens or closes) and the reset type – automatic or manual. The physical form of the probe (immersion, clamp-on, or integrated into the draught diverter assembly) must match the original installation. Cable length and connector type also affect interchangeability. Common failure modes include drift of the switching point, which can cause nuisance lockouts or unsafe operation, and mechanical damage to the probe or cable. During replacement, ensure the probe makes good thermal contact with the draught diverter surface if it is a clamp-on type. Always verify the thermostat's function by checking continuity before installation, as mechanical thermostats can fail either open or closed.