37
Main Thermostat
1
Loosen the screw on the capillary retaining washer,
allowing the washer to move freely. Free the
capillaries from the clips on the left hand side of the
combustion box. Withdraw both thermostat phials
from the thermostat pocket.
2
Disconnect the electrical plug and cable on the gas
valve.
3
Carefully pull off the thermostat knob. Loosen the
securing screw sufficiently for the electrical box cover
to be removed, remove cover.
4
Disconnect the wires of the input and pump outlet
cables from the terminal strips. Loosen the
screws on the cable clamps. Boilers
converted for use on gravity D.H.W. will
have wiring only to the left hand terminal
strip.
5
Unfasten the screws holding the
thermostat box to its bracket on
the boiler combustion box. The
thermostat box is now free of the
boiler.
6
Remove the rear part of the thermostat box
by removing the screws at the side.
7
Release the locknut securing the main boiler
thermostat to the mounting plate.
8
Pull off the spade connectors
from the rear of the thermostat, taking
note of their orientation.
Remove thermostat taking care not to
damage the PCB.
Fit the new thermostat to the mounting
plate and reconnect the spade
connectors to the appropriate
terminals.
Reassemble all
components in reverse
order. (See pages 24 and
25 for electrical
connections).
3
4
5
6
1
7
8
2