48/50PG and PM
Table 29 – Altitude Compensation* − 48PM16−20
NATURAL GAS
ELEVATION |
| NATURAL GAS ORIFICE SIZE† |
|
|
|
| |
(ft) | Low Heat (D,L) | Medium Heat (E,M) | High Heat (F,N) |
| 29 | 30 | 29 |
| 29 | 30 | 29 |
| 30 | 31 | 30 |
| 30 | 31 | 30 |
| 30 | 31 | 30 |
| 30 | 31 | 30 |
| 31 | 32 | 31 |
| 31 | 32 | 31 |
| 31 | 32 | 31 |
10,000 | 32 | 33 | 32 |
*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.
PROPANE GAS
ELEVATION |
| PROPANE GAS ORIFICE SIZE† |
|
|
|
| |
(ft) | Low Heat (D,L) | Medium Heat (E,M) | High Heat (F,N) |
| 35 | 38 | 35 |
| 36 | 39 | 36 |
| 36 | 39 | 36 |
| 37 | 40 | 37 |
| 37 | 40 | 37 |
| 38 | 41 | 38 |
| 39 | 42 | 39 |
| 40 | 43 | 40 |
| 41 | 44 | 41 |
10,000 | 42 | 45 | 42 |
*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.
Cleaning and Adjustment
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
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 48PM16−28 units, also remove the 2 screws se- curing 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.
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. 70.)
5.Reinstall burners on rack.
6.Reinstall burner rack as described above.
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