14.3.2 Connection options for the PCB (SCU-S03)
If the boiler is fitted with the PCB (SCU-S03), then this PCB is automatical
ly recognised by the boiler's automatic control unit.
Note
On removing this PCB, the boiler will show error code
. To
prevent this error, an auto-detect must be carried out after remov
ing this PCB.
For information on carrying out an auto-detect, see: Carrying out
an auto-detect, page 51
Connecting the minimum gas pressure switch (Gps)
The minimum gas pressure switch blocks the boiler if the gas inlet pres
sure becomes too low.
1. Connect the minimum gas pressure switch to the Gps terminals of
the connector.
The presence of the gas pressure switch must be set using parameter
.
Connecting a heat recovery unit (Hru)
1. Connect the wires from the heat recovery unit to the Hru terminals of
the connector.
The presence of the heat recovery unit must be set using parameter
.
14.3.3 Connection options for the PCB (SCU-X02)
It is possible to connect a 230 VAC three-way valve or a 24 VAC three-
way valve to the SCU-X02 PCB.
Note
The starting position of the three-way valve can be modified using
a jumper at Jp1.
Control of external three-way valve (3wV) 230 VAC
The external three-way valve (230 VAC) can be used when connecting an
indirectly heated calorifier.
1. Connect the three-way valve to the X3 terminals of the connector:
N = neutral
C = central heating
D = domestic hot water
Control of external three-way valve (3wV) 24 VAC
The external three-way valve (24 VAC) can be used when connecting an
indirectly heated calorifier. The neutral position of the three-way valve can
be set using parameter
.
1. Connect the three-way valve to the X4 terminals of the connector:
N = neutral
L = live (24 VAC)
C = common (CH or DHW)
Fig.73 SCU-S03 PCB
AD-0000058-01
SCU-S03
X2
X2a
X1
Tsol
Gps
Tsol
Gps
Hru
Hru
Fig.74 SCU-X02 PCB
AD-0000060-01
SCU-X02
2
C
1
Jp1
X2
X2a
X4
3wV
L
N
C
L
N
C
X3
X1
3wV
N C
3wV
N C D
D
F 2AT
14 Appendix
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123157 - v.06 - 24022015
