AERCO BMK 3.0 LN Natural Gas July 2011 - Manual (Page 40)

INITIAL START-UP
4-6
4.4 UNIT REASSEMBLY
Once the combustion calibration adjustments
are properly set, the unit can be reassembled for
service operation.
1. Set the ON/OFF switch in the OFF position.
2. Disconnect AC power from the unit.
3. Shut off the gas supply to the unit.
4. Remove the manometer and barbed fittings
and reinstall the NPT plug using a suitable
pipe thread compound.
5. Remove the combustion analyzer probe
from the vent hole. Replace the NPT plug in
the vent hole using a suitable pipe joint
compound.
6. Replace the unit’s side panels and front
door.
4.5 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 4-5. 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 4-5
Over Temperature Limit Switch
Locations