Actuator or cartridge only?

Diagnose first: manually push the actuator pin. If it moves freely, replace the actuator only; if the pin sticks, the cartridge is scaled.

A brass spanner or the OEM diverter tool avoids cracking the plastic body on Alpha E-Tec 28.

Do I need to notify the manufacturer?

Only if the Alpha E-Tec 28 is in warranty — Alpha require log of any part swap for labour claims.

Replace the diverter valve on Alpha E-Tec 28 when hot water runs cold on demand or the boiler cycles between CH and DHW.

Drain to below the diverter body via the CH drain-off. On Alpha E-Tec 28 the diverter is a cartridge design — pull the retaining clip and lift out.

Fit new O-rings, silicone-grease the cartridge and align the actuator drive slot before refitting the motor.

Refill the Alpha E-Tec 28 to 1.2 bar cold. Bleed high-point radiators and the internal AAV.

Run a full flue-gas analysis after 15 minutes. Log the reading against the OEM commissioning envelope in the Benchmark book.

Actuator or cartridge only?: Diagnose first: manually push the actuator pin. If it moves freely, replace the actuator only; if the pin sticks, the cartridge is scaled.
Any special tools?: A brass spanner or the OEM diverter tool avoids cracking the plastic body on Alpha E-Tec 28.
Do I need to notify the manufacturer?: Only if the Alpha E-Tec 28 is in warranty — Alpha require log of any part swap for labour claims.

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