Potterton NXR4 Installation, Operation & Maintenance Manual page 31

SECTION 6
PAGE 30
Wiring Diagram – Notes & Legend
Important: Maximum current rating at each terminal is 2A. Loads greater than 2A require isolating relays or
contactors, this particularly applies to pumps and fans.
Legend:
External Interlocks:
Fig. 20 – Pump Overrun Using Changeover Pipe Thermostat
Pump
POTTERTON COMMERCIAL PRODUCTS DIVISION
INSTALLATION, OPERATION & MAINTENANCE MANUAL
st
CH1 - 1 Stage Hours Run Meter
nd
CH2 - 2 Stage Hours Run Meter
F1 - 6.3 Amp Fuse
st
TR1 - 1 Stage Control Thermostat
nd
TR2 - 2 Stage Control Thermostat
STB - Overheat Thermostat
st
VMB1 - 1 Stage Indicator Light
nd
VMB2 - 2 Stage Indicator Light
VSB - Flame Failure Indicator Light
VSC - Overheat Indicator Light
MST - Mains Indicator Light
ZB - Burner Switch
ZT - Test Switch
ZP - Pump Switch
KA1 - Relay for Remote Indication – Overheat
KA2 - relay for Remote Indication – Burner Flame Failure
X1 - On/off Control (external interlock, boiler only)
X2 - Water Low Pressure Switch
X3 - Safety Interlock (eg. Flow switch, pressure switch)
X4 - Power Supply (230V 50Hz 1Ph) – maximum 5A
X5 - Boiler Pump
X6 - DHW Pump
Pipe Thermostat
Not controlled by boiler interlocks
L1
L2
L3
N
NO
C
NC
Set <55°C
Incoming
Supply
Auxillary Contact on
Boiler time control, etc
NXR4
L