28
LOW VOLTAGE CONNECTOR STRIP
AUX. DEVICE
PILOT SUPPLY
24VAC
GND
AUX. DEVICE
PROVING
GAS PRESSURE
SWITCH
FLOW
SWITCH
ALARM
CONTACTS
RUNTIME
CONTACTS
SYSTEM
SENSOR
AUXILIARY
SENSOR
OUTDOOR
SENSOR
SHIELD GROUND
0-10VDC EXTERNAL
GND CONTROL
DHW THERMOSTAT
R
W
ROOM THERMOSTAT/
ZONE CONTROL
A
B
SHIELD GROUND
SEQUENCING
L
OW
W
ATER
C
UTOFF
CN1
CN2
CN3
CN4
CN5
11
12
1
2
3
4
5
6
7
8
9
10
11
12
15
16
13
14
1
2
3
4
5
6
7
8
9
10
FIGURE 11.2
LOW VOLTAGE CONNECTION STRIP
PIN
CONNECTION
NOTES
CN1
1-2
EXTERNAL
CONTROL
When the boiler is to be controlled by a 0-10V DC analogue output from a Building Management System (BMS),
the 0V line should be connected to pin 1 and the 0-10V line should be connected to pin 2.
CN1
3-6
SEQUENCING
If the boilers are to be operated in a cascade, shielded 2-wire twisted pair communication cable should be used.
The shielding should be connected to pin 3 or 6 and then all “A” terminals (pin 5) should be linked together and
all “B” terminals (pin 4) should be linked together.
CN1
7-8
OUTDOOR
SENSOR
If the boiler is to be compensated to the outside temperature, an outdoor sensor should be connected to pins
7&8. This connection is not polarity sensitive.
CN1
9-10
AUXILIARY
SENSOR
A sensor located in an indirect calorifier can be connected to terminals 9 and 10 to control the output from the
boiler. This connection is not polarity sensitive. Not to be used in conjunction with the DHW thermostat
CN1
11-12
SYSTEM SENSOR
When configured in a cascade, the Master boiler will use the system sensor to monitor and control the output
from the cascade. This sensor should be mounted in the boiler flow.
CN2
1-2
ROOM T’STAT/
ZONE CONTROL
An on-off type thermostat or modulating room sensor can be connected to terminals 1 and 2 to control the
output from the boiler. This connection is not polarity sensitive.
CN2
3-4
DHW
THERMOSTAT
An on-off type thermostat located in an indirect calorifier can be connected to terminals 3 and 4 to control the
output from the boiler. This connection is not polarity sensitive. Not to be used in conjunction with the auxiliary
sensor
CN2
5-6
RUNTIME
CONTACTS
An internal volt free contact across pins 5 and 6 will close in the event of the burner operating. This connection
can be used by a BMS to monitor the operation of the boiler
CN2
7-8
ALARM
CONTACTS
An internal volt free contact across pins 7 and 8 will close in the event of the boiler locking out. This connection
can be used by a BMS to monitor the operation of the boiler.
CN2
9-10
FLOW SWITCH
If a flow switch is to be used to ensure the primary pump is operating, the link should be taken out of pins 9 and
10 and the flow switch wiring installed. If there is no continuity across the terminals the boiler will not fire.
CN2
11-12
GAS PRESSURE
SWITCH
If a gas pressure switch is to be used to ensure the incoming gas pressure is correct, the link should be taken
out of pins 11 and 12 and the gas pressure switch wiring installed. If there is no continuity across the terminals
the boiler will not fire.
CN2
13-14
AUX. PROVING
DEVICE
If an auxiliary device such as a fan dilution system or mechanical ventilation system is to be used, the link
should be taken out of pins 13 and 14 and the auxiliary deice safety circuit wiring installed. If there is no
continuity across the terminals the boiler will not fire.
CN2
15-16
AUX. DEVICE
PILOT SUPPLY
When the boiler gets a call for heat, a 24VAC supply becomes present on pin 16. Used in conjunction with the
ground pin (pin 15), these terminals can be used to send a signal to energise an auxiliary device such as a fan
dilution system or mechanical ventilation system.
TABLE 11.3
LOW VOLTAGE CONNECTION TERMINAL DETAILS
