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8
Maintenance
Heat exchanger cleaning
1.
While burners are removed, check the heat exchanger
surface for sooting. If present, heat exchanger must be
cleaned and problem corrected. Proceed as follows.
2.
Remove gas manifold(s)/orifice assemblies as described
in steps 1 through 5 in Burner Removal and Cleaning,
page 60.
3.
Disconnect wiring from the hot surface igniter and
hose from the burner pressure tap.
4.
Remove inner jacket panel mounting screws and slide
door assembly out toward front of the unit. Use
caution to prevent damage to the refractory and hot
surface igniter.
5.
Check "V" baffles and frame runners along front
and back edges of heat exchanger. Remove and clean if
necessary.
6.
Remove soot from heat exchanger with a stiff bristle
brush. Use a vacuum to remove loose soot from
surfaces and inner chamber.
7.
The heat exchanger can be removed by sliding towards
the front of the unit. Once the heat exchanger is
removed from the unit, a garden hose can be used
to wash the tubes to ensure that all soot is removed
from the heat exchanger surfaces. Note: Do not wet the
unit's refractory.
8.
Ensure that all burner ports are cleaned to remove any
soot. See Burner Removal and Cleaning, page 60.
9.
Carefully reinstall the heat exchanger, "V" baffles, and
frame runners if removed from the unit. Note: Make
sure frame runners seal securely where they contact the
front and rear compartment refractory.
10. Carefully reinstall inner jacket panels, burners,
manifolds, wires and hoses. Use new gasket material to
ensure a proper air seal.
11. Reassemble all gas and water piping. Test for gas leaks.
12. Reassemble outer jacket panels.
13. Cycle unit and check for proper operation.
Electrical
This unit uses a transformer to supply a low voltage control
circuit. The voltage on the secondary side should be 24 to
28VAC when measured with a volt meter. Larger models
have a 7AMP circuit breaker provided on the secondary
side of the transformer. A tripped circuit breaker indicates
a short in the 24VAC controls that must be corrected.
(continued)
Combustion and ventilation air
Combustion air filter
See Combustion Air Filter, page 13.
Air flow
Check frequently to be sure the flow of combustion and
ventilation air to the unit is not obstructed.
Combustion air fan
These units use a fan-assisted combustion process. These units
have one fan to supply combustion air to the burners.
Fan cleaning
Check combustion air fan every six months. Clean fan as
required only when installed in a dusty or dirty location. Oiling
is not required.
Combustion air fan adjustment
The combustion air fan is factory preset and should not need
adjustment in most cases. Follow the steps below to adjust the
fan if a continuous Low Air Status Code occurs.
Check for proper installation and draft in the venting system.
Correct as required.
Adjusting air pressure
The following is a recommended method for setting the air
pressure for the fan.
Setup procedure
To the left of the fan is an air pressure switch with a large and
small tube delivering pressure from points inside the unit
(see FIG. 8-2). The pressure in the large tube is the chamber
pressure. By disconnecting the cap from the tee in the hose and
connecting it to the "(+)" side of a manometer, you can read the
air chamber pressure.
Upon a call for heat, the fan will run for about 90 seconds
before going into soft lockout. If necessary, turn the power to
the unit OFF and then back ON again to recycle the fan.
Note:
Note:
Installation & Service Manual
If the unit has been firing recently, allow the unit to
cool for five minutes with the fan running before
beginning the adjustment procedure.
Retain the plastic cap removed from the tee for
reinstallation when complete.
61
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