De Dietrich S101726 Q65-Q85/Q90 fan

This De Dietrich fan, referenced as S101726 and 375.145.002, is listed in the fans and flue gas exhausters category. Parts of this type supply combustion air to the burner and, in room-sealed appliances, also evacuate flue gases. In modulating premix boilers, the fan speed determines the firing rate; the control varies the speed and the gas valve follows accordingly. Such fans are selected based on required air flow and pressure, the direction and orientation of the outlet, impeller diameter, and voltage as well as control mode (mains frequency, PWM, or 0-10 VDC). The flange pattern must also match the burner or boiler mounting. When replacing a fan of this class, common failure modes include worn bearings, imbalance caused by deposits on the impeller, a failed capacitor, or speed feedback errors that the boiler reports as an airflow fault. The fan interacts with the burner control and the air pressure switch; the pressure switch confirms adequate airflow during the pre-purge and operation. It is essential to verify the electrical supply and control signal compatibility before installation. The manufacturer code S101726 and catalogue number 375.145.002 should be cross-referenced with the original part to ensure correct fitment.