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Potterton Servomotor SBC28 Siemens 5138681

Potterton

Potterton Servomotor SBC28 Siemens 5138681

Siemens SBC28 servomotor, Potterton part 5138681, for Potterton Commercial Sirius SAT boilers.

Manufacturer part no.
5138681
Showing prices

£155.84

£129.87 ex. VAT · VAT at 20%

Available to order · 3 working days
Available to order · 3 working days
Not certain it's the right part? The technical team verifies fitment before dispatch — no charge, and it stops a second trip.Call the technical teamSend a technical question

Same-day dispatch

Ordered by 4pm Mon–Fri, 10:30am Sat.

30-day returns

Unused, in original packaging.

What it is

The SBC28 servomotor is a Siemens actuator supplied under Potterton part number 5138681. It drives the gas and air control damper on Potterton Commercial Sirius SAT boiler variants. The motor moves the damper in response to the boiler control signal to regulate combustion air and gas flow through the firing range.

Signs this part needs replacing

  • The damper no longer moves through its full travel when the boiler modulates.
  • Burner output stays fixed regardless of demand, with no modulation response.
  • Lockout or ignition faults that recur after the damper has been checked for free movement.
  • The actuator motor runs continuously, buzzes, or heats up without driving the linkage.
  • Visible mechanical damage or a detached linkage at the motor spindle.

Before you order

  • Confirm the boiler model against the Sirius SAT variants listed above.
  • Check the existing motor is marked SBC28 and note the wiring connections before removal.
  • Inspect the damper spindle and linkage for free movement, as a seized spindle can mimic motor failure.
  • Verify the boiler is isolated from the electrical supply before fitting.

Not sure which part?

Search by part number, product name or brand — our technical team confirms fitment before anything is dispatched.