INSTALLATION AND OPERATION INSTRUCTIONS
4-8
SL 26-260 G3, SL 40-399 G3 MODULATING GAS BOILERS
4.2.3 Replacing the gas valve
SL 26-260 G3
1. Turn off the electric power and gas supply to the boiler.
2. Remove the electrical connection from the gas valve.
3. Ensure the boiler cools to the surrounding temperature. Do not drain the boiler unless
freezing conditions are expected during this procedure.
4. Remove the front cover, and then remove the boiler's upper-front cover by removing
the two Phillips head screws at the top right and left corners of the boiler.
A ladder or step may be required to have a clear vertical view of the work area. Do
not attempt to reach from the front without a clear view as damage to the connectors,
screws, or refractory may occur.
5. Support the male compression coupling on the inlet of the gas valve, and with a
wrench, undo the compression fitting to separate the gas valve from the gas supply
pipe.
6. To separate the gas valve from the venturi mixing device, unscrew the brass coupler
nut and retain the gasket between the gas valve and the brass coupler.
7. Remove the male compression coupler from the old gas valve outlet, and install this
on the new gas valve outlet, using fuel-appropriate Teflon tape on the threads.
8.
Screw the brass coupler nut to the brass coupler flange on the left side of the gas
valve. Ensure that the gasket is in place.
9. Supporting the male compression coupling on the outlet of the gas valve, with a
wrench, tighten the compression fitting to secure the gas valve to the gas supply pipe.
SL 40-399 G3
1. Turn off the electric power and gas supply to the boiler.
2. Ensure that the boiler cools down to the surrounding temperature. Do not drain the
boiler unless freezing conditions are expected during this procedure.
3. Remove the front cover, and then remove the boiler's upper-front cover by removing
the two Phillips head screws at the top right and left corner of the boiler.
A ladder or step may be required to have a clear vertical view of the work area. Do not
attempt to reach from the front without a clear view, as damage to connectors, screws
or refractory may occur.
4. Noting the color and orientation of the connectors, unplug the 4 spade connectors
from the gas valve.
5. To separate the aluminium gas block on the right side of the gas valve, remove the 4
hex head bolts with a 4 mm hex key.
6. To separate the gas valve from the venturi mixing device, remove the 4 hex head
bolts on the left side of the gas valve with a 4 mm hex key.
7.
Bolt the gas valve to the venturi mixing device flange with the 4 mm hex bolts,
ensuring that the O-ring is positioned between the gas valve and the venturi mixing
device.
8. Bolt the gas block to the gas valve outlet, ensuring that the O-ring is positioned
between the gas block and the gas valve.
9. Connect the electrical connectors to the new gas valve.
