Sequence Of Operation; Variations; Terminations - Napoleon NBM030S2A Installation And Operating Instructions Manual

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4.7

SEQUENCE OF OPERATION

1. Room temperature drops causing the room thermostat call for heat by connecting "W" to "R". The control
verifi es the limit switch is closed and the pressure switch(s) are open. The control energizes the exhauster
motor and waits for the pressure switch(s) to close. The exhauster remains energized for a 15 second pre-
purge period. If the pressure switch(s) do not close within 60 seconds, the control will fl ash "2" on the Red
Status LED, and de-energize the exhauster for 60 minutes.
2. When the 15 second pre-purge time has elapsed, the control energizes the HSI output for a 5 second
UM
warm-up period (10 seconds on retries). The control energizes the gas valve. 4 seconds after the gas
is energized, the control de-energizes the HSI output and leaves the gas energized another 1 second
for fl ame proving. If fl ame is present at the end of trial for ignition time, the control leaves the gas valve
energized, exhauster on, and begins heat blower on delay.
3. Blower on delay time begins when the gas valve is energized.
4. Blower off delay is handled by the control board. When the thermostat "W" call ends, the control de-
energizes the gas valve, and starts the blower off delay period.
IN THE EVENT OF FLAME FAILURE:
If fl ame is lost, the control de-energizes the gas valve within 2 seconds, continues running the exhauster
motor, and begins timing the inter-purge delay. The indoor blower motor will be energized and/or remain
energized on heat speed for the delay off time. When the inter-purge delay is over, the control will re-cycle up
to 5 fl ame losses (4 re-cycles) within a single call for heat before going into lockout. The control fl ashes "8" on
the Red LED if lockout is due to too many fl ame dropouts (1 hour lockout).
4.8

VARIATIONS

If your system includes air conditioning, your thermostat will likely have two switches. The fi rst switch is the
system switch. The switch settings usually include HEAT, COOL, and OFF. Some thermostats have system
switches which include HEAT, COOL, AUTO, and OFF. The system switch must be in the HEAT or AUTO
position for the furnace to run.
The second switch is the fan switch. It usually has settings of ON and AUTO. The fan switch may be in either
position when using the furnace. If the fan switch is set to ON, the main blower will run continuously.
4.9

TERMINATIONS

The combustion air and exhaust terminals should be inspected occasionally to ensure that they are free of
obstructions and debris. If screens were used in either terminal, ensure that they are free of debris, corrosion,
or anything preventing the free fl ow of air.
W415-1117 / A / 03.11.14
H21.3.1A
H27.7
H27.8