Main Burners (48Pg And 48Pm) - Carrier 48/50PG Series Controls, Start-Up, Operation, Service And Troubleshooting Instructions

ELEVATION
(ft)
0-1,999
2,000
3,000
4,000
5,000
6,000
7,000
8,000
9,000
10,000
*As the height above sea level increases, there is less oxygen per cubic foot of air. Therefore, heat input rate should be reduced at higher altitudes. Includes a
4% input reduction per each 1000 ft.
†Orifices available through the local Carrier dealer.
ELEVATION
(ft)
0-1,999
2,000
3,000
4,000
5,000
6,000
7,000
8,000
9,000
10,000
*As the height above sea level increases, there is less oxygen per cubic foot of air. Therefore, heat input rate should be reduced at higher altitudes. Includes a
4% input reduction per each 1000 ft.
†Orifices available through the local Carrier dealer.
High Altitude (48PG and PM)
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 28 for orifice sizing. A high
altitude kit is available to convert unit for altitudes up to 7,000 ft.

Main Burners (48PG and 48PM)

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. For 48PG20- -28 and 48PM16- -28 units, also remove
the 2 screws securing the manifold bracket to the basepan.
9. Rotate the burner/manifold assembly to the right, away
from the flue extension and lift burner/manifold assembly
out of unit.
Table 29 – Altitude Compensation* - - 48PG20- -28 and 48PM16- -20
NATURAL GAS
Low Heat (D,L)
29
29
30
30
30
30
31
31
31
32
PROPANE GAS
Low Heat (D,L)
35
36
36
37
37
38
39
40
41
42
NATURAL GAS ORIFICE SIZE†
Medium Heat (E,M)
30
30
31
31
31
31
32
32
32
33
PROPANE GAS ORIFICE SIZE†
Medium Heat (E,M)
38
39
39
40
40
41
42
43
44
45
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. 81.)
5. Reinstall burners on rack.
6. Reinstall burner rack as described above.
97
High Heat (F,N)
29
29
30
30
30
30
31
31
31
32
High Heat (F,N)
35
36
36
37
37
38
39
40
41
42