Fuel Types And Pressures; Combustion-Air Blower - Carrier 48JCH 04-06 Series Service And Maintenance Instructions

Fuel Types and Pressures

NATURAL GAS
The 48JC unit is factory-equipped for use with natural gas (NG)
fuel at elevation under 2000 ft (610 m).
Units can not operated at altitudes greater than 2,000 feet
under any circumstances.
Gas line pressure entering the unit's main gas valve must be within
specified ranges (see Table 5). Adjust unit gas regulator valve as
required or consult local gas utility.
Table 5 — Natural Gas Supply Line Pressure Ranges
UNIT MODEL UNIT SIZE
48JC(G/H) 04, 05, 06
Manifold pressure is factory-adjusted for NG fuel use. Adjust as
required to obtain best flame characteristic (see Table 6).
Table 6 — Natural Gas Manifold Pressure
UNIT MODEL UNIT SIZE
48JC(G/H) 04, 05, 06
Burner Box Assembly
Combustion-Air
Blower Assembly
CAUTION
MIN MAX
5.0 in. wg 13.0 in. wg
(1.24 kPa) (3.23 kPa)
MANIFOLD PRESSURE
3.2 in. wg
(796 Pa)
Igniters
Manifold Pressure Tap
Fig. 43 — Heat Exchanger Assembly

Combustion-Air Blower

Clean periodically to assure proper airflow and heating efficiency.
Inspect blower wheel every fall and periodically during heating
season. For the first heating season, inspect blower wheel every
two months to determine proper cleaning frequency.
To access burner section, slide the burner partition panel out of
the unit.
To inspect blower wheel, shine a flashlight into draft hood open-
ing. If cleaning is required, remove motor and wheel as follows:
1. Remove the screw at the base of the burner partition panel
and slide out the panel (see Fig. 46).
2. Remove the four screws attaching the induced-draft motor
housing to the vestibule plate (see Fig. 43).
3. The blower wheel can be cleaned at this point. If additional
cleaning is required, continue with Steps 4 and 5.
4. Remove the blower from the motor shaft by removing two
setscrews.
5. Removing motor: remove the four screws holding the motor
to the mounting plate. Remove the motor cooling fan by
removing one setscrew. Remove nuts that hold the motor to
the mounting plate.
6. Reverse the procedure outlined above to reinstall the motor.
Heater Tube Assembly
Gas Valve
Gas Line
25
Vestibule Plate