Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Isolate cold mains and drain DHW circuit
Slacken the cold water inlet pipe and disconnect
Ease the DHW flow limiter from its seating

Observation:

Inspect the flow limiter for restrictions and any signs of damage.
Note:
The colour of the flow limiter will differ depending
upon the appliance model (see table opposite)