Laars NeoTherm NTH Installation and operation instructions manual - page 32
LAARS Heating Systems
Page 32
from the electrode. Remove the two bolts fastening the
electrode to the burner doors. Remove and replace the
old flame sensor gasket. Reinstall a new flame sensor
electrode in the reverse order if the old electrode is
determined defective.
Caution
Igniters and sensors get hot and
can cause burns or injury.
7.2.6 Transformers
There are various transformers used on the
NeoTherm units. Be sure to replace the transformers
with factory parts. These transformers are not capable of
supplying control voltage for external devices such as
zone valves, which must have their own separate power
supply. Should a transformer need replacing, shut off
the 120 Volt power. Unplug the transformer wires,
remove the mounting screws and remove the
transformer. Replace transformer in the reverse order.
7.2.7 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.
The 120 Volt current remains on to the blower at all
times. If a blower change is required, turn off the 120
Volt power and gas supply to the unit. Take the front
panel off. Disconnect the 120 Volt and control signal
connections from 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 above. Make sure to install all of the required O-
rings and gaskets between the blower arm and the
blower and blower face and venturi flange.
7.2.8 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 and 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 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.
For NT 500 models only (all other sizes please
skip to step four). NT 500 models will require the
gas valve to be removed in order to remove the
burner door. To do this, remove the wire
connections from the gas valve. Remove the flange
bolts from the gas supply pipe connected to the gas
valve (1B). Remove the flange bolts connecting
the gas train to the venturi (1A). Remove the gas
train assembly keeping gaskets and o-rings.
4.
Remove the four bolts connecting the blower
flange to the burner door arm.
5.
Remove the nuts located on the outside diameter
of the burner door to the heat exchanger.
6.
Remove the burner door/burner assembly from the
heat exchanger.
7.
Disconnect the condensate drain line.
8.
Attach a longer hose to drain and run to a bucket.
9.
Clean the heat exchanger by brushing light
accumulations of soot and debris. Use a brush with
soft bristle (non metal) to avoid damaging the
surface of the heat exchanger tubes.
10.
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.
11.
Install all components removed in the reverse
order to place the appliance back in operation.
Make sure all gaskets are in place as components
are installed. Replace any damaged gaskets. Do
NOT reuse damaged gaskets.