Spark & Flame Sensing Electrodes; Ignition & Flame Sensing Leads; Fan; Burner - Benchmark GB10 Design, Installation And Servicing Instructions

rEPLAcEMENT OF PArTS
9.2. Spark & Flame sensing Electrodes
For access refer to section General 9.1
Remove the spark plug style connector from the electrode and earth lead in the
case of the spark electrode. Remove the two retaining screws with a Torx T0 driver,
carefully withdraw the electrode from the combustion chamber.
9.3. Ignition & Flame sensing Leads
For access refer to section General 9.1
Pull off the spark plug style connector off the electrode and the spade connector
from the control pcb.

9.4. Fan

For access refer to section General 9.1 & 9.1.1
Remove the two slotted screws holding the gas valve and venturi to the fan then
remove the four nuts securing the fan to the gas manifold with a 8mm AF spanner.
Check and replace any seals and gaskets necessary.

9.5. Burner

For access refer to section General 9.1 & 9.1.1. Remove the three screws securing
the gas manifold to the combustion chamber front with a Torx T5 driver. This will
release the burner.
The burner size depend upon the model of the boiler (see table below) therefore
when replacing the burner ensure that the correct replacement burner is used.
Gledhill Boiler Burner length
model (mm)
GB10 9.6
GB15 104.6
GB0 135.8
GB5 167.0
GB30 167.0

9.6. Temperature Sensors

For access refer to section General 9.1
The flow and return sensors have built in retaining clips and are removed
as follows. Remove the electrical connections from the sensor, the sensor is
removed from the pipe by putting equal pressure on the sensor head and the
clip ends that are located 180
with a 15mm AF spanner after having its electrical connections removed.

9.7. Heat exchanger

For access refer to section General 9.1 & 9.1.1
After removing the burner sub-assembly drain the boiler and remove the
condense pipe from the bottom of the heat exchanger. Remove the clips
securing the flow and return connections onto the heat exchanger. Loosen the
three heat exchanger securing screws and clamps (two at the top and one at
the bottom) to remove the heat exchanger. CAUTION there will still be some
water in the heat exchanger.
Gledhill Part
number
GT991
GT99
GT993
GT994
GT994
o from each other. The flue gas sensor is removed

9.8. Insulation

For access refer to section General 9.1 & 9.1.1
Remove the sub assembly as described above and
replace the front insulation on the combustion
chamber front cover.

9.9. Overheat thermostat

For access refer to section General 9.1

9.10. Fuses

For access refer to section General 9.1
The fuse is located on the left hand side of the main
control pcb.

9.11. On-Off Switch

For access refer to section General 9.1
Remove the electrical connectors from the rear of
the switch, squeeze the holding tabs on each end
of the switch. The switch will now push through
the front panel.

9.12. Gas valve

The gas throttle on air/gas venturi (i.e. CO level)
and offset pressure settings of the gas valve fitted to
this boiler are factory set and sealed. These settings
should not be adjusted. The gas valve and Venturi
assembly must only be replaced by a factory set and
sealed replacement supplied by Gledhill Ltd.
Gas Council
number
For access refer to section General 9.1 & 9.1.1
Remove the three screws securing the gas valve
to the venturi using a Torx T5 driver. Check and
replace any seals and gaskets as necessary. After
replacing the gas valve the combustion CO will
need to be checked.

9.13. controller PcB

For access refer to section General 9.1
Remove the four slot screws securing the Perspex
cover and remove the wiring plugs from the pcb.
With a 6mm AF spanner remove the four nylon
stand offs securing the control pcb.
Page 34