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NXM2G DESCRIPTION
The NXM2G system is a microprocessor based boiler load optimization control system
designed to provide optimum thermal efficiency of Low Temperature Hot Water (LTHW)
boilers.
Control theory
The NXM2G measures the supply (flow) and return temperatures via digital sensors (supplied) and
monitors the “call for heat” via the Opto-isolators from the limit string wiring connections.
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On first firing, the boiler will reach the normal cut out set point and turn off,
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On the next burner cycle, the NXM2G will check:
i)
for the “call for heat ”
ii)
if the boiler flow and return temperatures are within the designed temperature
differential settings (parameter), and
iii)
if the boiler is required to fire, based on control algorithms.
When this occurs, the NXM2G will hold off the boiler firing (save mode) based on temperature and
time, which are both adaptive. The NXM2G will also inhibit the burner from firing on stage 2, if the
boiler load demand is low, thus ensuring the best efficiency for the current system demand.
NXM2G interface wiring
The NXM2G has 2 normally closed relays which are failsafe. These relays are wired in series to the
1st and 2nd stage operating control circuits. The relays operate according to whether the boiler is in
save mode or low fire save mode. The NXM2G has a series of LEDs that give the following indica-
tions:
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Power
230 VAC applied
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Thermostat on
Call for heat / 1st Stage thermostat closed
Blinking: "Save" mode
Steady: Boiler allowed to fire
WARNING:
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The installer must be suitably qualified and trained to install NXM2G.
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Follow the boiler manufacturer’s instructions.
NXM2G-2
Installation and
Operating Manual
NXM2G-1002
JULY 27, 2015
This manual must be affixed on or adjacent to the boiler or kept with boiler operating manual or other information.
(-2 CE version shown)
