2
•
Boiler firing
Call for heat / Boiler allowed to fire
Blinking: Burner purging
Steady: Boiler allowed to fire (or fuel valve open)
•
Stage 2 firing
Call for heat / 2nd Stage thermostat closed
Blinking: "Low Fire Save" mode
Steady: Stage 2 firing
Failsafe operation
In all cases the safety integrity of the boiler operation is not compromised. Moreover, the boiler set point
is always maintained. Should the NXM2G unit fail or lose electrical supply the boiler control system wir-
ing remains as normal and the boiler will operate as if the NXM2G were not installed. The boiler’s oper-
ating control is always in circuit and protected with the boiler high temperature limit.
NXM2G WIRING SCHEMATIC
Figure 1
shows the wiring of the NXM2G. The NXM2G has 4 separate plug connections for field
wiring.
FIGURE 1.
NXM2G Terminal Connections
FIGURE 2.
