LAARS MagnaTherm MGV - Installation, Operation and Maintenance Instructions - Manual (Page 70)

LAARS Heating Systems Page 66
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.
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.
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 appliance in operation according to
Section 9, checking all gas connections for
leaks. Confirm all fasteners are tight.
11.2.9 Gas Pressure Switches
The high and low gas pressure 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. 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 wires from the
screw terminals. Twist the switch off the pipe nipple.
Reassemble in reverse order.
Set the low gas pressure switch to 3” w.c.
Set the high gas pressure switch to 15”w.c..”