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SECTION 6
POTTERTON COMMERCIAL PRODUCTS DIVISION
INSTALLATION, OPERATION & MAINTENANCE MANUAL
PAGE 28
NXR3
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:
STB
-
Overheat thermostat
ZSB
-
Burner reset
ZT
-
Burner test switch
F1
-
Fuse
VSC
-
Overheat indicator light
MST
-
Mains indicator light
TR
-
Safety mode thermostat
TR1
-
1
st
stage regulation thermostat
TR2
-
2
nd
stage regulation thermostat
ZP
-
Pump switch (not used)
L
-
Live
N
-
Neutral
ZG
-
On/Off switch
BRU
-
Burner connections
H
-
Hours run counters
External Interlocks:
DG
-
External interlock
UV
-
Safety interlock
XY
-
Safety interlock
Relays -
Overheat & Fault
Fig. 20 - Pump Overrun Using Changeover Pipe Thermostat
L1
L2
L3
N
L
Incoming
Supply
Auxiliary Contact on
Boiler time control, etc
Pump
Pipe Thermostat
Set <55°C
NO
C
NC