International comfort products A Series Installation Instructions Manual page 48

k. Turn gas supply manual shutoff valve to OFF position.
l. Turn off furnace power supply.
m. Remove manometer from the inlet pressure tap of the gas
valve.
n. Tighten set screw on inlet tower pressure tap with
3/32 − in. hex wrench, or if 1/8
removed, apply pipe dope sparingly to end of plug and
re install in the gas valve
−
WARNING
!
FIRE HAZARD
Failure to follow this warning could result in personal injury,
death, and/or property damage.
Inlet pressure tap set screw must be tightened and 1/8- -in.
NPT pipe plug must be installed to prevent gas leaks.
4. Adjust gas valve outlet pressure determined in Step 2. to
obtain correct input rate.
a. Turn gas valve ON/OFF switch to OFF.
b. Loosen set screw on outlet
one full turn with a 3/32 in. hex wrench. (Fig. 60)
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 proceed
to next step.
NOTE: If 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.
Fig. 60 - - Gas Control Valve
48
− in. NPT plug was
tower pressure tap no more than
A180231
Specifications subject to change without notice.
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. Jumper R and W thermostat connections at the furnace
control board.
c. Run furnace for 15 minutes in heating operation.
d. 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.
e. For cubic ft. of gas per hr (Table 21).
f. 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. Restore furnace to normal operating condition.
a. When correct input rate and temperature rise is achieved,
turn gas valve ON/OFF switch to OFF.
b. Remove manometer or similar device from gas valve.
c. Tighten set screw on outlet tower
in. hex wrench.
d. Turn gas valve ON/OFF switch to ON.
e. Check for gas leaks and verify furnace operation.
7. Set temperature rise. The furnace must operate within the
temperature rise ranges specified on the furnace 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.
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.
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 radi-
ant heat from heat exchangers. Radiant heat affects temper-
ature rise readings. This practice is particularly important
with straight- -run ducts.
b. When thermometer readings stabilize, subtract return- -air
temperature from supply- -air temperature to determine air
temperature rise.
pressure tap with 3/32
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