hp-Technik FDR 20-E/2 bypass oil valve

The hp-Technik FDR 20-E/2 is an oil bypass valve used in oil burner fuel systems. Parts of this type regulate the return of surplus oil from the pump back to the tank, maintaining stable pressure at the nozzle during burner operation. They are typically integrated with the oil pump assembly and are a critical component in two-pipe systems where a continuous circulation loop is required. The valve works with the pump solenoid and the burner control to ensure clean fuel cut-off when the burner shuts down. When selecting a replacement bypass valve of this class, the engineer must match the rotation direction of the pump, the pipe configuration (single or two-pipe), the required capacity and pressure range, and the connection thread sizes. Attention should also be paid to the shaft and mounting pattern to ensure correct fit. Common failure modes for such valves include worn pressure regulation components, leaking seals, or solenoid coil issues that prevent clean fuel cut-off. The catalogue article 543.322.008 corresponds to the manufacturer code FDR 20-E/2. No further specifications for this specific article are available beyond its name and codes.