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When the main gas shutoff/control valve opens to attempt ignition, the high gas
pressure switch will trip, causing the NURO touchscreen to display 10011: "High
Gas Limit". Even after re-opening the downstream gas cock inside the boiler,
10011: "High Gas Limit" will remain on the NURO display until the boiler is
manually reset by pressing "Reset Control".
14. Test the ignition system safety shutdown as follows:
1. Cycle the boiler on by generating a heat request. (The method for this will
depend on your boiler configuration.)
2. During the pre-purge cycle (before ignition), smoothly close the downstream
manual isolation valve (inside the boiler cabinet) to reduce the gas flow.
3. Closing the manual isolation valve will prevent a successful ignition, and the
NURO will display either:
109: "Ignition Failed"
110: "Ignition Failure Occurred"
These alarms indicate an ignition failure and the lockout will remain until the
control is reset. After completing this test, turn the boiler off, open the
downstream manual isolation valve, then turn the boiler back on and reset the
control.
15.
Test the air switch for proper operation. Allow the boiler to start. Remove the tube from
the air switch, after 30 seconds the control should lock out on air switch not closed.
reinstall the tube and reset the boilers control.
16.
Testing the blocked flue switch. Allow the boiler to start, remove the blocked flue tube
from the condensate pan and apply a positive pressure to the tube. Verify that the
boiler locked out on a blocked flue error. Reinstall the blocked flue tube and reset the
control.
17.
To test the supply, return, flue, and heat exchanger temp sensors you will need to
disconnect one wire from each sensor. Verify that the boiler goes into a blocking error
for each correct sensor.
18.
To test the high limit, allow the boiler to start, then turn the high limit down slowly and
verify that the boiler locks out on high limit. the high limit should be at the same
temperature as the supply water temperature at the time that it trips. Turn the high limit
all the way up, reset the limit and reset the boilers control.
19.
In order to test the operating limit on the boiler, verify that the boiler turns on below the
setpoint minus the differential, and shuts down at the setpoint plus the off differential.
Instructions
NURO Conversion Instructions
MACH C1500-C2000H
1005101738
ENVI to NURO
Date: 12/19/2017
Revision A
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