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b. Jumper R, W/W1 and W2 thermostat connections on

control to run furnace in high heat. (See Fig. 32 and 51.)

c. Turn high-heat adjusting screw (5/64 hex Allen wrench)

counterclockwise (out) to decrease input rate or clockwise
(in) to increase rate.

d. Re-install high-heat adjustment caps.

NOTE:

DO NOT set high-heat manifold pressure less than 3.2-in.

wc or more than 3.8-in. wc for natural gas. If manifold pressure is
outside this range, change main burner orifices.

7. Verify natural gas high fire input rate by clocking meter.

NOTE:

Gas valve regulator adjustment caps must be in place for

proper input to be clocked.

a. Turn off all other gas appliances and pilots.

b. Run for 3 minutes in high-heat operation.

c. Measure time (in sec) for gas meter to complete 1 revolu-

tion and note reading.

d. Refer to Table 9 for cubic ft of gas per hr.

e. Multiply gas rate cu ft/hr by heating value (Btu/cu ft) to

obtain input.

NOTE:

Using the 2 cu. ft. or 5 cu. ft. gas meter dial provides

greater accuracy in verifying gas input rate.

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 until correct high fire
input is achieved. Re-install high-fire regulator seal cap on gas
valve.

8. Set high heat temperature rise.

Jumper R to W/W1 and W2 to check high-gas-heat tempera-
ture rise. Do not exceed temperature rise ranges specified on
unit rating plate for high fire.

NOTE:

Blower access door must be installed when taking tem-

perature rise reading. Leaving blower access door off will result in
incorrect temperature measurements.

a. Verify the unit is operating in high fire per Step 6. 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 important with
straight-run ducts.

b. When thermometer readings stabilize, subtract return-air

temperature from supply-air temperature to determine air
temperature rise.

Recheck temperature rise. It must be within limits specified
on the rating plate. Operation is within a few degrees of the
mid-point of rise range when setup switch SW1-4 is OFF.

When setup switch SW1-4 is ON, operation will be near the high
end of the rise range for improved comfort.

This furnace is capable of automatically providing proper airflow
to maintain the temperature rise within the range specified on unit
rating plate.

NOTE:

If the temperature rise is outside this range, first check:

1.) Gas input for low-and high-fire opeation.
2.) Derate for altitude if applicable.
3.) Return and supply ducts for excessive restrictions causing static
pressures greater than 0.50-in. wc.
4.) Make sure proper model plug is installed.

c. Remove thermostat jumpers and release blower access door

switch.

d. Repeat Steps a through c as required to adjust for proper

rise.

e. When correct high heat input rate and temperature rise is

achieved, turn gas valve ON/OFF switch to OFF.

f. Release blower access door switch.

g. Remove manometer or similar device from gas valve.

h. Re-install manifold pressure tap plug in gas valve. (See

Fig. 47.)

Failure to reinstall manifold pressure tap plug in gas valve
will result in fore, explosion, personal injury, property dam-
age or death.

i. Remove thermostat jumper wire from furnace control