De Dietrich 7628630 Fan

The De Dietrich 7628630 fan, also listed under catalogue article 375.145.074, is a centrifugal fan for heating appliances. In a boiler or burner system, parts of this type supply combustion air to the burner and, in room-sealed designs, drive the flue gases out through the exhaust. In modulating premix burners, the fan speed directly sets the firing rate; the burner control varies the speed and the gas valve follows. The fan works in sequence with the air pressure switch, which must confirm airflow before the ignition sequence proceeds, and with the burner control that commands its operation. When selecting a replacement fan of this class, key parameters include the required air flow and pressure, the direction and orientation of the outlet, the impeller diameter, and the supply voltage. The control mode must match the system: some fans run directly from the mains, others accept a PWM or 0-10 V signal from the control board. The flange pattern also needs to align with the mounting on the burner housing. Typical failures in such fans include worn bearings, imbalance from deposits on the impeller, a failed running capacitor, and speed feedback errors that the control interprets as an airflow fault, often resulting in a lockout. Inspecting the impeller for debris and verifying the capacitor condition are routine checks during service.