1-35
BOILER SYSTEMS AND OPERATION
SFC COMBI BOILERS SFC-99, SFC-125
Figure 36: Junction box schematic
To install an external junction box to supply power and access to up to two pump
relays:
1.
Pull out the controller as shown in Figure 34.
2.
At the back of the tray, knock out the hole nearest to the power cord using a
flathead screwdriver.
3.
Feed the junction box cable through the hole and secure to the tray with the
connector nut.
4.
Connect the blue wire to the X4 terminal, position 3
.
5.
Connect the red wire to the X3 terminal, position 3.
6.
Screw the junction box to the wall within six feet of the tray.
•
Allow clearance for plug use.
•
Allow wire enough slack for easy removal of the tray.
7.
Drill out both holes in the junction box.
8.
Bring AC Power to terminals labelled
Power Inlet
.
9.
Wire the pump(s) to the junction box.
•
Wire the space heating pump to terminals labeled
Relay 1
.
•
Wire the DHW pump to terminals labeled
Relay 2
.
If using both relays, wire the pumps to the box with a duplex BX connector.
10.
Install the junction box cover.
Note:
If the junction box is installed AC power must be supplied to the SFC
series boiler through the junction box. Do not plug the unit in elsewhere.
NOTES
- The IBC unit (like any modern
appliance that contains
electronic equipment), must
have a “clean” power supply,
and can be disabled by power
surges and spikes, lightning
strikes and other forms of
severe electrical “noise”.
Power conditioning equipment
(surge protectors, APC or UPS
devices) may be required in
areas where power quality is
suspect.
- The IBC control typically uses
a true dry contact closure as
a call for heat. A signal from
an Open Therm device can
also be used. Thermostats and
other devices that use a “Triac”
output cannot be used as a call
for heat without the installation
of an intervening relay with dry
contacts to connect to the IBC
terminal strip.
- A hot water unit installed
above radiation level or as
required by the Authority
Having Jurisdiction, must
be provided with a low water
cut-off device at the time of
unit installation. If a low water
cut-off is not factory installed,
instructions shall be provided
for the installation and wiring
of a low water cut-off.
