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120
Gas Valve Adjustment (48PG Only)
The gas valve opens and closes in response to the thermostat or
limit control.
When power is supplied to valve terminals W2 (High Fire) and
C1, the main valve opens to its preset position.
The regular factory setting is stamped on the valve body.
To adjust regulator:
1. Set unit at setting for no call for heat.
2. Turn main gas valve to OFF position.
3. Remove
1
/
8
-in. pipe plug from manifold pressure tap
connection. Install a suitable pressure-measuring device.
4. Set main gas valve to ON position.
5. Set thermostat at setting to call for heat.
6. Remove screw cap covering regulator adjustment screw
(See Fig. 56).
7. Turn adjustment screw clockwise to increase pressure
or
counterclockwise to decrease pressure. The setting is 3.50
in. wg on sizes 03-14 and 3.00 on size 16.
8. Once desired pressure is established, set unit setting for no
call for heat, turn off main gas valve, remove
pressure-measuring device, and replace
1
/
8
-in. pipe plug
and screw cap.
High Altitude (48PG Only)
For high altitude applications greater than 2,000 ft the heat input
rate should be reduced. The higher the altitude is above sea level,
the less oxygen is in the air. See Table 106 for orifice sizing. A
high altitude kit is available to convert unit for altitudes up to
7,000 ft.
Main Burners (48PG Only)
For all applications, main burners are factory set and should
require no adjustment.
Main Burner Removal
1. Shut off (field-supplied) manual main gas valve.
2. Shut off power to unit.
3. Open gas section access door.
4. Disconnect gas piping from gas valve inlet.
5. Remove wires from gas valve.
6. Remove wires from rollout switch.
7. Remove sensor wire and ignitor cable from IGC board.
8. Remove 2 screws that hold the burner assembly to
vestibule plate.
9. Rotate the burner/manifold assembly to the right, away
from the flue extension and lift burner/manifold assembly
out of unit.
Cleaning and Adjustment
1. Remove burner rack from unit as described in Main
Burner Removal section above.
2. Inspect burners, and if dirty, remove burners from rack.
The two outer burners have the flame crossover closed off
in order to prevent gas flow from exiting the sides of the
burner assembly. To prevent ignition problems, make sure
the outer burners are returned to their original position
when done servicing.
3. Using a soft brush, clean burners and crossover port as
required.
4. Adjust spark gap. (See Fig. 57.)
5. Reinstall burners on rack.
6. Reinstall burner rack as described above.
E
E
A
A
B
B
25.4
MAX. TYP.
SPARK GAP
0.120 TO 0.140”
[3.05 TO 3.56]
D
D
E-E
SECTION
SCALE 2:1
D-D
SECTION
B-B
SECTION
SCALE 1:1
A-A
SECTION
SCALE 1:1
C-C
SECTION
C
C
SPARK GAP
0.181”
[4.6]
C06269
Fig. 57
---
Spark Gap Adjustment
48/
50P
G
C
03
--
16