Start−Up, Adjustment, And Safety Check - International comfort products R8MXL Installation Instructions Manual

5. Four−inch single−wall (26 ga. min.) vent must be used
inside furnace casing and when the Downflow Vent
Guard Kit is used external to the furnace.
6. Accessory Downflow Vent Guard Kit, required in
downflow installations with lower vent configuration.
7. Chimney Adapter Kit may be required for exterior
masonry chimney applications. Refer to Chimney
Adapter Kit, for sizing and complete application details.
8. Secure vent connector to furnace elbow with (2)
corrosion−resistant
approximately 180_ apart.
9. Secure all other single wall vent connector joints with
(3) corrosion resistant screws spaced approximately
120_ apart. Secure Type−B vent connectors per vent
connector manufacturer's recommendations.
START−UP, ADJUSTMENT, AND SAFETY
CHECK
Step 1 —General
WARNING
!
FIRE HAZARD
Failure to follow this warning could result in personal
injury, death and/or property damage.
This furnace is equipped with manual reset limit
switches in the gas control area. The switches open
and shut off power to the gas valve if a flame rollout or
overheating condition occurs in the gas control area.
DO NOT bypass the switches. Correct inadequate
combustion air supply problem before resetting the
switches.
CAUTION
!
CUT HAZARD
Failure to follow this caution may result in personal
injury.
Sheet metal parts may have sharp edges or burrs.
Use care and wear appropriate protective clothing,
safety glasses and gloves when handling parts and
servicing furnaces.
1. Maintain 115−v wiring and ground. Improper polarity
will result in rapid flashing LED and no furnace opera-
tion.
2. Make thermostat wire connections at the 24−v terminal
block on the furnace control. Failure to make proper
connections will result in improper operation. (See
Figure 26)
3. Gas supply pressure to the furnace must be greater
than 4.5−in. w.c. (0.16 psig ) but not exceed 14−in. w.c.
(0.5 psig).
4. Check all manual−reset switches for continuity.
5. Install blower compartment door. Door must be in place
to operate furnace.
6. Replace outer door.
30
sheet metal screws, spaced
Specifications are subject to change without notice.
Step 2 —Start−Up Procedures
WARNING
!
FIRE AND EXPLOSION HAZARD
Failure to follow this warning could cause personal
injury, death and/or property damage.
Never test for gas leaks with an open flame. Use a
commercially available
specifically for the detection of leaks to check all
connections.
1. Purge gas lines after all connections have been made.
2. Check gas lines for leaks.
3. To Begin Component Self−Test:
Remove blower access door. Disconnect the thermo-
stat R lead from the furnace control board. Manually
close the blower door switch closed. Short (jumper) the
C terminal on control to the TEST/TWIN 3/16−inch
quick connect terminal on control until LED goes out
(approximately 2 sec). Gas valve and humidifier will not
be turned on. (See Figure 25)
WARNING
!
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal
injury, or death.
Blower access door switch opens 115−v power to
control. No component operation can occur unless
switch is closed. Caution must be taken when
manually closing this switch for service purposes.
NOTE: The furnace control allows all components, except
the gas valve, to be run for short period of time. This feature
helps diagnose a system problem in case of a component
failure. Component test feature will not operate if any
thermostat signal is present at the control.
Component test sequence is as follows:
Refer to service label attached to furnace or see Figure 44.
a. LED will display previous status code 4 times.
NOTE: If no previous code is present, go directly to b.
b. Inducer motor starts and continues to run until Step g
of component test sequence.
c. Hot surface igniter is energized for 15 sec., then off.
d. Blower motor operates on HEAT speed for 10 sec.
e. Blower motor operates on COOL speed for 10 sec.
f. Inducer motor stops.
g. Reconnect R lead to furnace control board, release
blower door switch and re−install blower door.
4. Operate furnace per instruction on door.
5. Verify furnace shut down by lowering thermostat setting
below room temperature.
6. Verify furnace restarts by raising thermostat setting
above room temperature.
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