Transformer; Clock/Programmer; Fan; Air Flow Detector - Worcester 28Si Installation And Servicing Instructions

15.4.11 Transformer

Remove the cabinet and lower the facia panel as described in
Section 14, Inspection and Servicing.
Unscrew the four screws and remove the metal cover. Refer to Fig
54.
Pull out the transformer. Refer to Fig 56.
Fig.56. Transformer
Transformer

15.4.12 Clock/Programmer

Remove the clock/programmer assembly by carefully pulling it
from the facia to release the clips. Unplug the connector at the
control board. Comprehensive instructions are sent with the new
control. Refer to Fig 57.
Fig.57. Programmer connection
Facia
Programmer
connector
Programmer
connections
Clip
Programmer

15.4.13 Fan

Remove the inner casing.
Remove the fan as described in Section 14.3, Inspection and
Servicing. Ensure that all the connections are correctly made to
the new fan.

15.4.14 Air Flow Detector

Remove the fan as described in 15.3.13 preceding.
Unscrew and , through the fan outlet, withdraw the airflow
detector. Refer to Fig 42.
15.4.15 Primary [CH] Sensor
Remove the cabinet and inner casing.
Carefully pull-off the connections.
Withdraw the clip and lift off the sensor. Refer to Fig 58.
Control board
Facia
Control
board
Pressure gauge
Do not omit the heat transfer paste when fitting the replacement
sensor.
15.4.16 Overheat Thermostat
Remove the cabinet and the inner casing.
Carefully pull-off the connections. Unscrew the two screws and
remove the sensor. Refer to Fig 58.
Fig.58. Primary sensor and overheat
thermostat
Overheat
thermostat
leads
(orange)
Fixing screws
Overheat
thermostat
Mounting
plate
Apply a small quantity of heat transfer paste to the face of the
replacement sensor.
Carefully reposition the sensor so that the connections are away
from the flue hood. Reconnect the sensor.
15.4.17 DHW Sensor
Remove the cabinet and lower the facia.
Carefully pull off the connections. Unscrew the clip and remove
the sensor.
Apply a small quantity of heat transfer paste to the face of the
replacement sensor.
Refer to Fig 59.
Fig.59. Domestic hot water sensor
Cenral heating
flow pipe
Air flow
switch
Fixing
screws
26
Flue hood
Mounting
plate
Domestic hot
water
flow
pipe
Fixing clip
Sensor leads
(yellow)
Primary
sensor leads
(red)
Primary
sensor
Fixing clip
Domestic hot
water
temperature
sensor