37
7.7.1 Replacement of modulating
regulator
•
Isolate the boiler from the electrical
supply.
•
Remove front casing as in section
7.1.3 .
•
Lower front control panel as in
section 7.1.6
•
Turn off the gas service valve (1,
fig. 50).
•
Loosen screw (1, fig. 61) and pull
off rectifier plug (2, fig. 61) from
the gas operator.
•
Pull off modulating coil wires (4,
fig. 61).
•
Remove modulating regulator by
removing 2 screws (3, fig. 61) and
pull regulator from gas valve body.
•
Reassemble in reverse order.
•
Set burner pressure in accordance
with instructions supplied with spa-
re parts.
•
Carry out electrical checks (see
section 5.1).and test all gas joints
for soundness.
1
4
2
3
fig. 61
GW 644/1
7.8 Replacement of main heat
exchanger
•
Turn off the boiler as in section
7.1.1.
•
Remove front casing as in section
7.1.3 and remove combustion
chamber cover as in section 7.1.5
•
Remove heat exchanger front panel
as in section 7.1.7
•
Release CH water pressure and
drain boiler as in section 7.1.2.
•
Remove burner assembly as in
section 7.4.
•
Pull off wire from NTC (4, fig. 62)
•
Disconnect flow and return
connections (3, fig 62)
•
Slide the heat exchanger forward
to remove.
•
Disconnect flow and return pipes
from the heat exchanger by
rotating at joints (bayonet fix)
•
Reassemble in reverse order.
•
Recommission boiler (see section 5).
5
4
2
3
1
6
fig. 62
GW 641/1
