Specifications
2
5. Disconnect gas piping at unit gas valve.
NOTE: Use a backup wrench to avoid twisting the gas manifold
pipe.
6. Remove wires connected to gas valve. Mark each wire to
ensure proper reassembly.
7. Remove wires connected to the flame rollout switch. Mark
wires.
8. Remove wires connected to igniter and flame sensor. Mark
wires.
9. Remove the four screws that attach the gas manifold pipe to
the burner bracket and rotate the pipe away from the unit.
The pipe should NOT be removed from the wire bundle
connecting to the IGC (integrated gas controller) board.
(See Fig. 3.)
CONTROL BOX
AND
COMPRESSOR
OUTDOOR AIR
SCREEN
(HIDDEN)
FILTER ACCESS DOOR
GAS SECTION
ACCESS
INDOOR MOTOR
ACCESS DOOR
ELECTRICAL
OPTIONS PANEL
BASEPAN CONNECTIONS
ACCESS PANEL
CONDENSER COIL
ACCESS PANEL
C07002
Fig. 1 -- Panel and Filter Locations (48PG03--07 Unit Shown)
INDUCED
DRAFT
MOTOR
COMBUSTION
FAN HOUSING
MAIN GAS
VALVE
MAIN BURNER SECTION
HEAT EXCHANGER
SECTION
ROLLOUT
SWITCH
C07037
Fig. 2 -- Typical Gas Heating Section
Step 2 — Replace Orifice Fittings
1. Remove standard orifice fittings from the manifold pipe.
2. Select the correct orifice size based on local elevation. Refer
to Table 1.
3. Install new orifice fittings.
NOTE: Pipe sealant is not required. Never use Teflon tape on
fitting threads since loose pieces may plug gas orifices.
Step 3 — Reinstall Manifold Pipe
1. Attach manifold pipe to the burner bracket using four
screws. (See Fig. 3.) Make sure that all orifice fittings are
properly seated in the burner inlets.
2. Reconnect wires to the igniter, flame sensor, flame rollout
switch, and gas valve.
3. Reconnect gas piping to the gas valve.
Step 4 — Check Unit Operation and Make
Necessary Adjustments
NOTE: Gas pressure must not be less than 5--in. wg or greater
than 13--in. wg at the unit connection.
1. Remove pressure tap plug from manifold pipe and connect
a pressure gauge or manometer.
2. Turn on electrical supply.
3. Open the manual shutoff valve on the gas supply piping.
Check pipe connection to main gas valve for leaks.
4. Set the switch on the main gas valve to the ON position.
5. Call for high stage heat (W2 energized). The unit may
require several ignition attempts due to trapped air in the
manifold pipe.
6. When main burners ignite check orifice fittings for leaks.
Repair if necessary.