Danfoss Oil pump BFR21 R5 071N0260

This is a gear-type oil pump from Danfoss for small and medium household burners. It has a fuel consumption of up to 42 l/h and operates within a pressure range of 7000–20000 mbar. A built-in filter cleans the fuel, and an NC valve, regulator, and pressure maintenance system control the flow. The shaft is made of EN225 and rotates at 1400–3450 min⁻¹. Suitable fuel viscosity is 1.8–12.0 cst, and ambient temperature may range from −20 to 70 °C.

Oil pumps of this type are selected to match the burner's fuel consumption rate and the required pressure range. Replacement requires checking the model designation and ensuring the new pump has the same shaft rotation speed (1400–3450 min⁻¹ for this series) and viscosity range compatibility (1.8–12.0 cSt in the suction line). The pump must fit the existing mounting points and control connections for the NC valve and regulator.

When an oil pump fails, the burner typically produces incomplete combustion, reduced flame intensity, or complete flame failure. Signs include excessive fuel smell from unburned oil, weak ignition, or the burner struggling to restart. Check for fuel flow at the nozzle and verify pump pressure with a gauge; abnormally low or fluctuating pressure indicates pump wear or internal seal failure.