14 Electrical Connections - IDEAL Concord CXA120 Installation & Servicing Manual

14 ELECTRICAL CONNECTIONS

Connection must be made in a way that allows complete
isolation of the electrical supply - such as a double pole
switch, having a 3mm (1/8") contact separation in both poles,
or a plug and socket serving only the boiler and system
controls. The means of isolation must be accessible to the
user after installation.
This should serve only the boiler, together with its controls
and pumps. The unswitched live supply, which the boiler
requires to allow the pump overrun facility to operate, should
be controlled by the above switched/fused supply, but should
connect from there directly to the boiler and not via any
automatic time or temperature controls.
The switched live supply should be subject to control by time
and temperature controls in the usual way.
The controls incorporate a pump overrun facility, which is
necessary to dissipate residual heat on plant shutdown. It is
essential, therefore, that the main pump (and shunt pump if
fitted) is wired to the pump terminals marked L2 , N and Earth
on the plug-in terminal strip on the top box at the rear of the
control box.
The mains supply to the boiler must be wired to the boiler
terminals L1, N and Earth on the plug-in terminal strip. This
live connection must be unswitched, that is a supply not
interrupted by any automatic temperature or time control, to
enable the pump overrun (and the frost protection facility) to
operate.
Failure to operate this procedure will result in nuisance
overheat thermostat operation.
If the down draught flue thermostat is to be fitted then the link
(marked TTB) should be removed from the plug-in connector.
15 CONTROLS ASSEMBLY
Remove the 2 screws from the box at the bottom of the
control box back panel and push in the terminal plug-in
connector containing the gas valve wiring harnesses;
secure with the 2 screws.
Fit the earth terminals to the earth post at the left hand
side of the control box back panel.
Undo the 2 screws securing the control box front panel
and carefully lower it. Undo the stress relief clamp
situated on the left hand side of the control box above
the grommeted hole.
Free the sleeving containing the spark electrode lead
and the flame detector lead and pass the terminals
and sleeving through the grommetted hole; connect
them to the appropriate terminals of the S4561B1054
PCB; refer to wiring diagram Frame 16.
Refit the stress relief clamp ensuring that the sleeving
passes through the clamp before tightening.
14
INSTALLATION
The internal wiring of the boiler control box is shown in Frame
16.
Wiring should be in four core PVC insulated cable, not less than
0.75mm (24/0.2mm). All fuses must be ASTA approved to BS.
2
1362.
The length of the conductors between the cord anchorage and
the terminals must be such that the current carrying conductors
become taut before the earthing conductor, if the cable or cord
slips out of the cord anchorage.
The boiler can be controlled either by volt-free external contacts
connected between terminals X1 and X2 or by a switched live
supply brought to X2 (after removal of the factory-fitted link between
X1 and X2), accompanied in each case by a permanent live supply
to terminal L1.
If a separate frost thermostat is fitted it must be wired across the
time switch contacts and if frost is likely the system should be
turned off using the time switch settings - all other controls
including the boiler thermostat knob should be in the normal
running position.
The earth connections MUST NEVER be omitted.
Wire the earths as shown in Frames 13 and 16.
All wiring between entry at the rear of the boiler and the
connection box must be secured neatly under the cable clips
provided.
Wiring must never be allowed to come into contact with the hot
boiler body.
Do not wire these connections in conduit up to the boiler as this
will make it impossible to remove the control box for servicing or
maintenance.
If fitted, a flow switch should be wired between F1 and F2 on the
terminal plug in connector on the bottom box at the rear of the
control box.
Stress relief
clamp
Grommetted
hole
Flame detector
Spark electrode
lead terminal
lead terminal
S546B1054
PCB
Concord CXA
- Installation and Servicing