Gas Pressure Measurement; High Altitude Information; Proper Combustion - Lennox Allied Air A96UHMV Installation Instructions Manual

9. Replace the access panel.
10. Turn on all electrical power to the unit.
11. Set the thermostat to desired setting.
NOTE: When unit is initially started, steps 1 through 11
may need to be repeated to purge air from gas line.
12. If the Appliance will not operate, follow the instructions
"Turning Off Gas to Unit" and call the gas supplier.
Turning Off Gas to Unit
1. Set the thermostat to the lowest settling.
2. Turn OFF all electrical power to the unit if service is to
be performed.
3. Remove the access panel.
4. Move the gas valve switch to the OFF position.
5. Replace the access panel.
Failure To Operate
If the unit fails to operate, check the following:
1. Is the thermostat calling for heat?
2. Are access panels securely in place?
3. Is the main disconnect switch closed?
4. Is there a blown fuse?
5. Is the filter dirty or plugged? Dirty or plugged filters will
cause the limit conrol to shut the unit off.
6. Is gas turned on at the meter?
7. Is the manual main shut Off valve open?
8. Is the gas valve turned on?
9. Is the unit ignition system in lock out: If the unit locks
out again, inspect the unit for blockages.
10. Is blower harness connected to ignition control? Furnace
will not operate unless harness is connected.

Gas Pressure Measurement

Gas Flow (Approximate)
Furnace should operate at least 5 minutes before checking
gas flow. Determine time in seconds for two revolutions of
gas through the meter. (Two revolutions assures a more
accurate time.) Divide by two and compare to time in Table
21. If manifold pressure matches Table 24 and rate is
incorrect, check gas orifices for proper size and restriction.
Remove temporary gas meter if installed.
Page 50 of 66
Table 21
NOTE: To obtain accurate reading, shut off all other gas
appliances connected to meter.
Supply Pressure Measurement
A threaded plug on the inlet side of the gas valve provides
access to the supply pressure tap. Remove the threaded
plug, install a field provided barbed fitting and connect a
manometer to measure supply pressure. Replace the
threaded plug after measurements have been taken.

Proper Combustion

Furnace should operate a minimum of 15 minutes with
correct manifold pressure and gas flow rate before checking
combustion. Take combustion sample beyond the flue outlet
and compare to the tables below. The maximum carbon
monoxide reading should not exceed 50 ppm.

High Altitude Information

NOTE: In Canada,certification for installationa at elevations
over 4500 feet (1372 m) is the jurisidiction of local authorities.
These units require no manifold pressure adjustments for
operation at altitudes up to 7,500 feet (2286 m) above sea
level. Table 24 lists conversion kit requirements, pressure
switch requirements and manifold pressures at all altitudes.
The combustion air pressure switch is factory set and
requires no adjustment.
NOTE: A natural to LP/propane gas changeover kit is
necessary to convert this unit. Refer to the changeover kit
installation instruction for the conversion procedure.
Issue 1230
High Fire
Table 22
Low Fire
Table 23
506550-01