F96CTN and G96CTN (Series A): Installation, Start-up, Operating, Service and Maintenance Instructions
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
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Clocking the Meter
Verify natural gas input rate by clocking meter.
NOTE:
Contact your HVAC distributor or gas supplier for metric gas
meter tables, if required.
1. Turn off all other gas appliances and pilots served by the meter.
2. Move setup switch SW1-2 to ON position. This keeps furnace
locked in low-heat operation when only W/W1 is energized.
3. Jumper R to W/W1.
4. Run furnace for 3 minutes in low-heat operation.
5. Measure time (in sec) for gas meter to complete one revolution and
note reading. The 2 or 5 cubic feet dial provides a more accurate
measurement of gas flow.
6. Refer to
7. Multiply gas rate cu ft./hr by heating value (BTUh/cu ft.) to obtain
input rate.
8. If clocked rate does not match required input from Step 1, increase
manifold pressure to increase input or decrease manifold pressure
to decrease input. Repeat steps b through e of Step 1 until correct
low-heat input is achieved. Re-install low heat regulator seal cap on
gas valve.
9. Jumper R to W/W1, and W2. This keeps furnace locked in
high-heat operation when both W/W1 and W2 are energized.
10. Repeat items d through g for high-heat operation, repeating Step 2
and adjusting the high-heat regulator screw as required.
11. Restore furnace to normal operating condition.
A11461
Fig. 64 – Burner Flame
12. Turn gas valve ON/OFF switch to OFF.
13. Remove water column manometer or similar device from manifold
pressure tap.
14. Tighten set screw on manifold pressure tap with 3/32-in hex
wrench, or if 1/8-in. NPT plug was removed, apply pipe dope
sparingly to end of plug and reinstall in the gas valve.
15. Turn gas valve ON/OFF switch to ON.
16. Move setup SW1-2 on furnace control to position required for
attached thermostat (OFF for single-stage thermostats, ON for
two-stage thermostats).
17. Check for gas leaks and verify furnace operation.
Adjust Temperature Rise
NOTE:
Blower door must be installed when taking temperature rise
reading. Leaving blower door off will result in incorrect temperature
measurements, due to possible changes in duct static pressure and
airflow.
When setup switch SW1-4 is ON, operation will be near the high end of
the rise range for improved comfort.
Furnace must operate within ranges of temperature rise specified on the
furnace rating plate. Determine air temperature rise as follows:
1. Place thermometers in return and supply ducts as near furnace as
possible. Be sure thermometers do not see heat exchanger so that
radiant heat does not affect readings. This practice is particularly
important with straight-run ducts.
2. When thermometer readings stabilize, subtract return-air
temperature from supply-air temperature to determine air
temperature rise.
NOTE:
Temperature rise can be determined for low-heat and high-heat
operation by locking the furnace in each mode of operations. The mode
of operation is based on the position of Setup Switch SW1-2 on the
furnace control board.
3. This furnace is capable of automatically providing proper airflow to
maintain the temperature rise within the range specified on furnace
rating plate. If temperature rise is outside this range, proceed as
follows:
a. Check gas input for low- and high-heat operation.
b. Check derate for altitude, if applicable.
c. Check all return and supply ducts for excessive restrictions
causing static pressure greater than 0.5-In. W.C.
d. Ensure setup switch SW1-4 (See
for switch location.)
e. Make sure proper model plug is installed.
To lock the furnace in low heat:
1. Turn SW1-2 ON at the furnace control.
2. Connect a jumper across R and W/W1 at the thermostat terminals at
the furnace control.
3. Allow the burners to ignite and the blower to turn on.
4. Allow the supply temperature to stabilize and verify the proper rise
range.
If the temperature rise is too high or too low in low heat:
1. Remove jumpers from R and W/W1.
2. Wait until the blower off delay is completed.
3. Turn 115 VAC power off.
4. Check the position of setup switch SW1-4. When set to OFF,
airflow is raised 7% for low heat. Factory default position is ON.
5. Turn 115 VAC power on.
6. Re-check low heat temperature rise.
To lock the furnace in high heat:
1. Connect a jumper across R and W/W1 and W2 at the thermostat
terminals at the furnace control.
2. Allow the burners to ignite and the blower to turn on.
3. Allow the supply temperature to stabilize and verify the proper rise
range.
If the temperature rise is too high or too low in high heat:
1. Remove jumpers from R and W/W1 and W2.
WARNING
!
FIRE HAZARD
Failure to follow this warning could result in personal injury, death,
and/or property damage.
Manifold pressure tap set screw must be tightened or
⅛
-in. NPT pipe
plug must be installed to prevent gas leaks.
Burner Flame
Burner
Manifold
CAUTION
!
FURNACE DAMAGE HAZARD
Failure to follow this caution may result in:
• Overheating the heat exchangers or condensing flue gases in heat
exchanger areas not designed for condensate.
• Shortened furnace life
• Component damage.
Temperature rise must be within limits specified on furnace rating plate.
Recommended operation is at midpoint of rise range or slightly above.
