Worcester Bosch Differential Pressure Switch 87161165410

The Worcester Bosch 87161165410 is a differential pressure switch used in the hydraulic and manifold section of Worcester 28 CDi RSF combi boilers. It monitors the pressure difference across the water circuit and signals the control board when the required condition is reached, so the boiler can move through its start sequence and hold a stable output. The switch is a direct replacement item for the 28 CDi RSF range in both LPG and natural gas variants.

• The boiler runs through its pre-purge but does not fire, with the fan running and no ignition sequence following.
• Repeated lockouts or fault codes that clear on reset and return once the appliance is asked for heat or hot water.
• Hot water output that fluctuates or drops away as the boiler modulates, despite the pump running normally.
• Intermittent operation where the boiler fires correctly on some calls for heat and fails on others.
• A switch that no longer changes state when the pressure difference across the circuit is applied, confirmed by meter testing at the terminals.

• Check the appliance GC number and serial plate against the compatibility list, as the 28 CDi RSF was produced in both LPG and natural gas versions.
• Compare the number on the existing switch with 87161165410 and the previous numbers listed above before fitting.
• Inspect the seals and connections on the hydraulic assembly while the switch is removed, and renew any that show hardening or leakage.
• This part is fitted to a gas appliance; installation must be carried out by a Gas Safe registered engineer.