LAARS NeoTherm LC NTV1700 - Install and Operating Manual - Manual (Page 96)

LAARS Heating Systems Page 92
11.2.7 Blower
The combustion air blower is a high-pressure
centrifugal blower with a variable speed motor. The
speed of the motor is determined by the control
logic. 120 Volts are supplied to the blower at all
times.
If it is necessary to replace the blower, turn off the
120 Volt power and the gas supply to the unit. Take
the front panel off. Disconnect the 120 Volt and
control signal connections to the blower. Disconnect
the bolts connecting the Venturi to the blower
housing. Disconnect the fan outlet bolts from the
burner door blower arm. If the fan is determined to
be defective replace the existing fan with a new one
reversing the steps listed above. Be sure to install
all of the required O-rings and gaskets between the
blower arm and the blower and blower face and
Venturi flange.
11.2.8 Heat Exchanger Coils
Black carbon soot buildup on the external surfaces
of the heat exchanger is caused by one or more of
the following; incomplete combustion, combustion
air problems, venting problems or heater short
cycling. Soot buildup or other debris on the heat
exchanger may restrict the flue passages.
If black carbon soot buildup on the heat exchanger
is suspected, disconnect the electrical supply to
the unit, and turn off the gas supply by closing
the manual gas valve on the unit. Access the heat
exchanger through the burner door at the front of
the boiler, and inspect the tubing using a flashlight.
If there is a buildup of black carbon soot or
other debris on the heat exchanger, clean per the
following:
Caution
Black carbon soot buildup on a dirty heat
exchanger can be ignited by a random spark or
flame. To prevent this from happening, dampen
the soot deposits with a wet brush or fine water
spray before servicing the heat exchanger.
1. Shut off the 120 Volt power supply to the
boiler.
2. Turn off all manual gas valves connecting the
boiler to the main gas supply line.
3. Remove the nuts located on the outside
diameter of the burner door to the heat
exchanger.
4. Remove the burner door/burner assembly from
the heat exchanger.
5. Disconnect the condensate drain line.
6. Attach a longer hose to the drain and run it to a
bucket.
7. Clean the heat exchanger by brushing away
any light accumulations of soot and debris. Use
a non metallic brush with soft bristles to avoid
damaging the surfaces of the heat exchanger
tubes.
8. Once the tubes have been brushed clean, rinse
the tubes and combustion chamber with a small
amount of water to rinse all of the debris out
of the bottom of the flue collector and into the
longer condensate trap line, which is being
diverted into a separate container.
Note - The Warranty does not cover damage
caused by lack of required maintenance, lack of
water flow, or improper operating practices.
WARNING
Failure to rinse the debris from the heat
exchanger and temporary drain line may lead to
clogged condensate lines, traps and neutralizers.
Condensate pumps (if used) may also be
damaged from the debris left behind, possibly
causing property damage.
9. To place the unit back in operation, install all
removed components in the reverse order. Be
sure all gaskets are in place as the components
are installed. Replace any damaged gaskets. Do
not reuse damaged gaskets.
10. Place the appliance in operation according to
Section 9, checking all gas connections for
leaks. Confirm all fasteners are tight.
11.2.9 Gas Pressure Switches (optional)
The high and low gas pressure switches are 24V
manual reset switches that act to cut power to the gas
valves if the gas pressure is too low or too high for
proper operation. The gas pressure switches used are
integrally vent limited, and do not require venting to
atmosphere. To remove a switch, remove the screw
on the plastic housing and pull the clear cover off.
Disconnect the two wires from the screw terminals.
Twist the switch off the pipe nipple. Reassemble
in reverse order. For natural gas, set the low gas
pressure switch to 3” w.c. For propane, set the
low gas pressure switch to 5” w.c. For natural and
propane, set the high gas pressure switch to 14.”