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 126)
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 - item 71)
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 nut, 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 - item 65)
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 using the drain off tap
(Fig. 6.7.4 - item 66) at the base of the return pipe from the heat exchanger.
v)
Remove the push on connectors from the pressure sensor taking note of the
correct positions.
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 Chapter 5 - Commissioning).
8.4.6
Main Control Box (Fig. 6.7.1 - item 111)
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 retaining screw (Fig. 6.7.1 - item 113) securing the control block
to the gas valve (Fig. 6.7.3 - item 96).
v)
Remove the control box.
vi)
Reassemble (Section 8.3)
8.4.7
Combustion Blower (Fig. 6.7.3 - item 91)
i)
Isolate the appliance (Section 8.1)
ii)
Gain access (Section 8.2)
iii)
Disconnect the two connector blocks from the combustion blower.
iv)
Unscrew the bolts securing the venturi (Fig 6.7.3 - item 95) to the inlet port of
the combustion blower.
v)
Remove the four nuts securing the combustion blower (Fig. 6.7.3 - item 93)
outlet flange to the burner and remove the combustion blower.
vi)
Reassemble (Section 8.3)
NB:
When reassembling inspect any gaskets for damage and replace if
necessary.
8.4.8
Gas Control Valve /Venturi Assembly (Fig. 6.7.3 - item 96)
i)
Isolate the appliance (Section 8.1)
ii)
Gain access (Section 8.2)
iii)
Remove the Main Control Box (Section 8.4.6)
iv)
Remove the push on connector block to the gas valve.
WD500
Chapter 8 : Replacement Of Parts The Keston Q37 & Q37P Boilers
Installation & Servicing Instructions
Page : 45
