v)
Remove the Control Panel by removing the four retaining screws (Fig 6.7.1,
item 160).
vi)
Reassemble (Section 8.3)
vii)
Check for correct operation of the Control Panel.
8.4.2
Boiler Flow and Return Thermistors
(Fig. 6.7.2 - 1/2 & 2/2 item 58)
i)
Isolate the appliance (Section 8.1)
ii)
Gain access (Section 8.2)
iii)
Remove the push on connectors from the thermistor taking note of the correct
positions.
iv)
Unclip the thermistor from the pipe.
v)
Reassemble (Section 8.3)
NB
:
When fitting the new thermistor it is an advantage to smear a thin film
of
heat sink compound between the thermistor and pipe. This,
combined with fitting the new thermistor tightly to the pipe, ensures a
good contact.
8.4.3
Cabinet Temperature Sensor
(Fig 6.7.1 item 151)
i)
Isolate the appliance (Section 8.1)
ii)
Gain access (Section 8.2)
iii)
Remove the cabinet temperature sensor from the connector block by
slackening the retaining screws.
iv)
Reassemble (Section 8.3)
8.4.4
Flue Thermistor
(Fig. 6.7.2 - 1/2 item 59)
i)
Isolate the appliance (Section 8.1)
ii)
Gain access (Section 8.2)
iii)
Remove the push on connectors from the thermistor taking note of the correct
positions.
iv)
Unscrew the retaining nuts, and remove the thermistor.
v)
Reassemble (Section 8.3)
NB
:
When fitting the new thermistor it is an advantage to smear a thin film
of heat sink compound between the thermistor and plate. This,
combined with fitting the new thermistor tightly to the plate, ensures a
good contact.
8.4.5
Pressure Sensor
(Fig. 6.7.2 - 2/2 item 101)
i)
Isolate the appliance (Section 8.1)
ii)
Shut off the water supply to the appliance.
iii)
Gain access (Section 8.2)
iv)
Drain the system to below the level of the appliance.
v)
Remove the push on connector from the pressure sensor.
vi)
Unscrew the pressure sensor.
vii)
Reassemble (Section 8.3).
NB
:
Use a little jointing compound or PTFE tape on the thread.
viii)
Refill the system (See Section 5 - Commissioning).
NB
:
When reassembling inspect the oring (Fig 6.7.2 - 2/2, item 100) for
damage and replace if necessary.
8.4.6
Main Control PCB
(Fig. 6.7.1 item 131)
i)
Isolate the appliance (Section 8.1)
ii)
Gain access (Section 8.2)
iii)
Pull off the multi-pin connectors and HT lead away from the board.
iv)
Remove the plastic box cover by pulling it from support.
v)
Remove the control PCB by pulling it from the four support plastic pins.
vi)
Reassemble (Section 8.3)
WD420/3/2007 Chapter 8 : Replacement Of Parts
The Keston Qudos 28s & Qudos 28sP
Boilers
Installation & Servicing Instructions
Page : 47
