International comfort products N80ESU Installation Instructions Manual page 25

b. Loosen set screw on outlet tower pressure tap no more
than one full turn with a 3/32 in. hex wrench. (See Fig.
32)
c. Connect a water column manometer or similar device to
pressure tap on the gas valve.
d. Turn gas valve ON/OFF switch to ON.
e. Manually close blower door switch.
f. Set thermostat to call for heat.
g. Remove regulator seal cap and turn regulator adjusting
screw counterclockwise (out) to decrease input rate of
clockwise (in) to increase input rate.
h. Install regulator seal cap.
i. Leave manometer or similar device connected and pro-
ceed to next step.
NOTE: If orifice hole appears damaged or it is suspected to have
been redrilled, check orifice hole with a numbered drill bit of
correct size. Never redrill an orifice. A burr- -free and properly
sized orifice hole is essential for proper flame characteristics.
5. Verify natural gas input rate by clocking meter.
NOTE: Gas valve regulator adjustment cap must be in place for
proper input to be clocked.
a. Turn off all other gas appliances and pilots served by the
meter.
b. Run furnace for 3 minutes in heating operation.
c. Measure time (in seconds) for gas meter to complete 1
revolution and note reading. The 2 or 5 cubic feet dial
provides a more accurate measurement of gas flow.
d. Refer to Table 11 for cubic ft. of gas per hr.
e. Multiply gas rate (cu ft./hr) by heating value (Btuh/cu ft.)
to obtain input.
If clocked rate does not match required input from Step 1,
increase gas valve outlet pressure to increase input or decrease gas
valve outlet pressure to decrease input. Repeat steps b through e
until correct input is achieved. Reinstall regulator seal cap on gas
valve.
6. Set temperature rise. The furnace must operate within the
temperature rise ranges specified on the furnace rating
plate. Do not exceed temperature rise range specified on
unit rating plate. Determine the temperature rise as
follows:
NOTE: Blower access door must be installed when taking
temperature rise reading. Leaving blower access door off will
result in incorrect temperature measurements.
WARNING
!
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury
or death.
Disconnect 115- -v electrical power and install lockout tag
before changing speed tap.
a. Place thermometers in return and supply ducts as close
to furnace as possible. Be sure thermometers do not see
radiant heat from heat exchangers. Radiant heat affects
temperature rise readings. This practice is particularly im-
portant with straight- -run ducts.
b. When thermometer readings stabilize, subtract return- -air
temperature from supply- -air temperature to determine air
temperature rise.
NOTE: If the temperature rise is outside this range, first check:
(1.) Gas input for heating operation.
441 01 1501 04
c. Adjust air temperature rise by adjusting blower speed. In-
d. Turn thermostat down below room temperature and re-
e. To change motor speed selection for heating, remove
f. Repeat steps a through e.
g. When correct input rate and temperature rise is achieved,
h. Remove manometer or similar device from gas valve.
i. Tighten set screw on
Specifications are subject to change without notice.
(2.) Return and supply ducts for excessive restrictions
causing static pressures greater than the maximum
heating static listed on the rating plate.
crease blower speed to reduce temperature rise. Decrease
blower speed to increase temperature rise
move blower access door.
blower motor lead from control HEAT terminal (See
Wiring Diagram - - Fig. 38) Select desired blower motor
speed lead from one of the other terminals and relocate
it to the HEAT terminal (See Table 5 for lead color identi-
fication). Reconnect original lead to SPARE terminal.
turn gas valve ON/OFF switch to OFF.
outlet tower pressure tap with 3/32
in. hex wrench.
Fig. 32 - - Gas Control Valve
Fig. 33 - - Orifice Hole
A180231
A180238
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