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8 - ELECTRICAL CONNECTIONS
Connection Option For PCB (SCU-S02)
If boiler is fitted with control PCB (SCUS02) it will
automatically be recognized by the automatic boiler control.
If removing this PCB boiler will show fault code E38. To
prevent this fault, auto-detect must be done after removing
the PCB. See Auto-Detect.
LED status indicator D3 top right of control PCB indicates
status:
• Continuous signal: PCB working normally.
• Flashing signal: No connection.
• No signal: No voltage or faulty PCB (Check wiring).
1.
Heating System External Pump Control -
External
pump for heating system can be connected to Pump
terminals of control board. Maximum input power is 300
VA/ 0.4 FHP. Auxiliary relay must be used for pump with
larger input.
2.
External Three-Way Valve (3WV) Control -
External
three-way valve (120 VAC) can be used when connecting
DHW indirectly water heater. Neutral position of three-way
valve can be set using parameter
P34
. Three-way valve is
connected as follows:
• N = neutral
• C = heating system
• D = indirect tank
If neutral position of three-way valve is adjusted with
parameter
P34
connect the pump as follows:
• N = N pump.
• C = L pump.
•
= Ground
3.
External Gas Valve Control -
If there is a call for heat,
alternating voltage of 120 VAC, 1 A (maximum) becomes
available on EgV terminals of control board to control an
external gas valve.
4.
Operation Signal And Failure Signal (EgV)
- Alarm or
operation signal is selected using parameter
P40
.
• If boiler is operating, operation signal can be switched
using dry set of contacts (maximum 120 VAC, 1 A) on
NO
and
C
terminals of the connection.
• If boiler locks out, alarm can be transmitted using dry
set of contacts (maximum 120 VAC, 1 A) on
No
and
C
terminals of connection.
5.
Pressure Switch Minimum GPS -
minimum gas
pressure switch shuts boiler down if inlet gas pressure
becomes too low. Connect minimum gas pressure switch
to Gps terminals. Presence of gas pressure switch must be
set using parameter
P41
.
FIGURE 8-9 Analog Output 0-10V
P/N 240011654, Rev. C [06/08/2017]