Page 109
HTD
11.B.8 Heat Exchanger Tubes
Black carbon soot build-up 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 heat exchanger shrouds. Removal of the outer
baffles may be required for proper inspection. Use 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 main power supply to the boiler.
2. Turn off all manual gas valves connecting the boiler
to the main gas supply line.
3. Remove the blower assembly and burner from the
heat exchanger.
4. Disconnect the condensate drain line.
5. Attach a longer hose to the drain and run it to a
bucket.
6. 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.
7. 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.
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.
8. 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.
9. Place the unit into operation, checking all gas
connections for leaks. Confirm all fasteners are tight.
11.B.9 Gas Pressure Switches
The high and low pressure gas switches are 120 volt
manual reset switches that act to cut power to the
interlock circuit if the gas pressure is too low or too high
for proper operation. There is a manual reset on both.
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
three (3) wires from the screw terminals. Twist the
switch off the pipe nipple. Reassemble in reverse order.
Set the low pressure gas switch to 3” w.c.
Set the high pressure gas switch to 15”w.c.”
NOTE - The Warranty does not cover damage
caused by lack of required maintenance, lack of water
flow, or improper operating practices.
