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Service Manual
59
6. Adjust the air shutter on the right fan until the differential
pressure is nominally 1.1-1.3 inches water column.
7. Once the adjustment procedure is complete, reattach the
caps to the tees in the hoses to the pressure switches and
check all tubing and wire connections for snug fit. Test fire
the unit. Install upper panels.
FIG. 59 Combustion Air Adjustment with a Manometer to
set Differential Pressures
Servicing Hot Surface Igniter and
Ignition Module
This unit uses a proven hot surface ignition control module and
a hot surface igniter. The hot surface ignition module is not
repairable. Any modification or repairs will invalidate the
warranty.
A faulty hot surface igniter or ignition module must be
replaced with an identical part. A specification igniter and
ignition control module for this specific unit is available from
your local distributor. Do not use general purpose field
replacement ignition modules or igniters.
Ignition System Checkout
1. Turn off gas supply to unit.
2. Turn electric power on.
3. Program each stage of the temperature control to settings
above water temperature or to the highest safe setting.
4. Each igniter will cycle on trial(s) for ignition.
5. Each ignition module will lock out and turn the alarm light
on.
6. Program each stage of the temperature control to the
desired temperature set points.
7. Turn on gas supply.
8. Press the module reset buttons (located on the front of the
unit) to reset modules.
9. If ignition system fails to operate properly, repair work
must be performed by a qualified service person or
installer.
SEQUENCE OF OPERATION
OVERVIEW
This sequence of operation can be considered the order of
events in sequential order that occur after the unit has received
a call for heat. The process begins with 120VAC power
entering the unit and ends with the unit going into an idle state
after completion of a successful call for heat. Note: The
following descriptions do not include remotely connected
devices that may be connected to the unit. Refer to the
wiring diagram for actual point to point wiring connections
that show power delivery.
POWER SUPPLY
120VAC/60Hz/1PH power connects to black (line) and white
(neutral) wires located within an electrical wiring box located
on the left side of the unit. A green chassis grounding wire is
also provided for connection to earth ground.
ON/OFF ROCKER SWITCH
The black line voltage wire runs directly to a single pole, single
throw On/Off rocker switch located behind the front cover
accessible by a thumb screw. Turning ON the rocker switch
delivers line voltage to the low voltage transformer and
ignition modules. Note: The On/Off switch does not
provide for disconnection of power being supplied to any
remotely connected devices that may be connected to the
unit (i.e. pumps, louvers, power venters, etc.). As such, it
may be necessary to locate and turn off power to these
items before attempting to service the unit.
LOW VOLTAGE SUPPLY TRANSFORMER
A 120VAC to 24VAC transformer located within the control
panel provides 24VAC/60Hz to many of the components
located on the unit. One of its 24VAC outputs (blue) is
connected to a circuit breaker and the other (yellow) is
connected to chassis ground.
24VAC CIRCUIT BREAKER
A circuit breaker is provided for protection of the low voltage
supply transformer from overloads and short circuits. The
breaker is located inside the unit on the right rear of the control
panel. Power from this breaker goes to the electronic
temperature controller, ignition module and various other
components and/or options on the unit. When tripped, all
factory-installed 24VAC components will lose their 24VAC
power.
ƽ WARNING: Do not attempt to repair a faulty
hot surface igniter or ignition module. Any
modification or repairs may create hazardous
conditions that result in property damage,
personal injury, fire, explosion and/or toxic
gases.