Flue Gas Passageways; Combustion-Air Blower; Burners And Ignitors - Carrier WeatherExpert 48LC 14 Series Service And Maintenance Instructions

Table 8 — Liquid Propane Manifold Pressure Ranges
UNIT MODEL UNIT SIZE
All
48LC
SUPPLY PRESSURE SWITCH
The LP conversion kit includes a supply low pressure switch. The
switch contacts (from terminal C to terminal NO) will open the
gas valve power whenever the supply line pressure drops below
the setpoint. (See Fig. 30 and 31.) If the low pressure remains
open for 15 minutes during a call for heat, the IGC circuit will ini-
tiate a Ignition Fault (5 flashes) lockout. Reset of the low pressure
switch is automatic on rise in supply line pressure. Reset of the
IGC requires a recycle of unit power after the low pressure switch
has closed.
LOW REGULATOR COVER SCREW
(TWO STAGE ONLY)
REGULATOR ADJUST SCREW
REGULATOR SPRING
PILOT COVER SCREW
PILOT GASKET
PILOT ADJUST SCREW
Fig. 30 — LP Low Pressure Switch (Installed)
IGC
BRN C
J2-11
IGC
J2-12
TSTAT
W2 PNK
Fig. 31 — LP Supply Line Low Pressure Switch
This switch also prevents operation when the propane tank level is
low which can result in gas with a high concentration of impuri-
ties, additives, and residues that have settled to the bottom of the
tank. Operation under these conditions can cause harm to the heat
exchanger system. Contact your fuel supplier if this condition is
suspected.

Flue Gas Passageways

To inspect the flue collector box and upper areas of the heat
exchanger:
1. Remove the combustion blower wheel and motor assembly
according to directions in "Combustion-Air Blower" section.
(See Fig. 32.)
2. Remove the flue cover to inspect the heat exchanger.
3. Clean all surfaces as required using a wire brush.
HIGH FIRE LOW FIRE
10.0 in. wg 5.0 in. wg
(2490 Pa) (1245 Pa)
SINGLE STAGE AND TWO STAGE
HIGH REGULATOR COVER SCREW
REGULATOR ADJUST SCREW
REGULATOR SPRING
OUTLET PRESSURE TAP
LP LPS
BRN
NO
MGV
GRA
Wiring

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 bi-
monthly to determine proper cleaning frequency.
To access burner section, slide the sliding burner partition 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 7 screws that attach induced-draft motor housing
to vestibule plate. (See Fig. 32.)
2. The blower wheel can be cleaned at this point. If additional
cleaning is required, continue with Steps 4 and 5.
3. To remove blower from the motor shaft, remove 2 setscrews.
4. To remove motor, remove the 4 screws that hold the motor to
mounting plate. Remove the motor cooling fan by removing
one setscrew. Then remove nuts that hold motor to mounting
plate.
5. To reinstall, reverse the procedure outlined above.
SCREWS
BURNER
ASSEMBLY
Fig. 32 — Heat Exchanger Assembly

Burners and Ignitors

C
EQUIPMENT DAMAGE HAZARD
Failure to follow this CAUTION can result in premature wear
and damage to equipment.
When working on gas train, do not hit or plug orifice spuds.
MAIN BURNERS
To access burners, remove burner access panel and slide out burn-
er partition. At the beginning of each heating season, inspect for
deterioration or blockage due to corrosion or other causes. Ob-
serve the main burner flames and adjust, if necessary.
Orifice projection
Refer to Fig. 33 for maximum projection dimension for orifice
face to manifold tube.
23
VESTIBULE
MANIFOLD
PLATE
PRESSURE TAP
GAS VALVE
CAUTION