AERCO BMK 3.0 LN Dual-Fuel Series Gas Fired Low NOx Boiler System - Manual (Page 41)

INITIAL START-UP
4-9
47. Press the ▼ arrow key until CAL Voltage
18% is displayed.
48. Press the CHANGE key. CAL Voltage 18%
will begin to flash.
49. The oxygen level at the 18% valve position
should be as shown below. Also, ensure that
the carbon monoxide (CO) and nitrogen
oxide (NOx) readings do not exceed the
values shown.
Combustion Oxygen Level at
18% Valve Position
Oxygen %
± 0.2
Carbon
Monoxide NOx
5.5 % <100 ppm <100 ppm
50. If the oxygen level is not within the specified
range, adjust the level using the ▲ and ▼
arrow keys. This will adjust the output
voltage to the blower motor as indicated on
the display. Pressing the ▲ arrow key
increases the oxygen level and pressing the
▼ arrow key decreases the oxygen level.
51. Once the oxygen level is within the specified
range at 18%, press the ENTER key to store
the selected blower output voltage for the
16% valve position.
52. This completes the Propane Combustion
Calibration procedure.
4.5 UNIT REASSEMBLY
Once the combustion calibration adjustments
are properly set for Natural Gas and Propane,
the unit can be reassembled for service
operation.
1. Access the Control Panel Configuration
Menu and ensure that the Max Valve
Position is set to the desired level for the
fuel being used for service operation (100%
for Natural Gas; 75% for Propane).
2. Set the control panel ON/OFF switch to the
OFF position.
3. Disconnect AC power from the unit.
4. Shut off the gas supply to the unit.
5. Set the Fuel Selector Switch to the
corresponding position for the fuel being
used for service operation.
6. Remove the manometer and barbed fittings
and reinstall the NPT plug using a suitable
pipe thread compound.
7. Remove the combustion analyzer probe
from the vent hole. Replace the NPT plug in
the vent hole using a suitable pipe joint
compound.
8. Replace the unit’s side panels and front
door.
4.6 OVER-TEMPERATURE LIMIT
SWITCHES
The unit contains both automatic and manual
reset over-temperature limit switches. These
switches are mounted on a plate attached to the
boiler shell as shown in Figure 4-7. The switches
can be accessed by removing the left side
panels of the unit. The manual reset switch is
not adjustable and is permanently fixed at
200°F. This switch will shut down and lock out
the boiler if the water temperature exceeds
200°F. Following an over-temperature condition,
it must be manually reset by pressing the
RESET button before the boiler can be
restarted. The automatic reset over-temperature
switch is adjustable and allows the boiler to
restart, once the temperature drops below its
temperature setting. Set the automatic over-
temperature switch to the desired setting.
RESET BUTTON FOR MANUAL
RESET TEMPERATURE LIMIT
SWITCH
ADJUSTABLE
TEMPERATURE
LIMIT SWITCH
MOUNTING
PLATE
ON SHELL
HIGH LIMIT
Figure 4-7
Over Temperature Limit Switch
Locations