Potterton PCB (FS70) 5142461

The PCB (FS70) is the control board used on Potterton Commercial Sirius 2 and Sirius 3 boiler appliances. It governs the sequencing of burner ignition, fan operation, pump control and safety interlocks, and it carries the boiler's fault and lockout logic. The board is supplied as a complete printed circuit board assembly, part number 5142461.

• The boiler locks out repeatedly, with the fault clearing only after a power cycle or not at all
• No heating or hot water despite demand, with the pump or fan failing to run
• The boiler fires intermittently or drops out mid-cycle without a clear external cause
• Burner ignition sequencing is erratic, or the appliance behaves differently after each reset
• Visible damage to the board, such as burnt tracks, scorching, leaking capacitors or corrosion

• Confirm the appliance model and variant against the boiler's data plate before ordering
• Match the part number on the existing board to 5142461, as board variants are not interchangeable across models
• Check the condition of related components, such as sensors, the fan and the ignition electrode, so a failed peripheral is not mistaken for a board fault
• Isolate the power supply and follow the manufacturer's wiring and safety instructions when fitting