280241-YIM-D-0909
Johnson Controls Unitary Products
21
Adjust as follows:
1.
Remove the cap from the valve body. See Figures 13
and 14 for location.
2.
To decrease the gas pressure, turn the adjusting screw
counterclockwise.
3.
To increase the gas pressure, turn the adjusting screw
clockwise.
NOTE:
The correct manifold pressure for natural gas fur-
naces is 3.5 IWG High Heat and 1.5 IWG Low Heat.
The correct manifold pressure for propane (LP) is
10.0 IWG High Heat and 4.5 IWG Low Heat.
BURNER INSTRUCTIONS
To check or change the burners, CLOSE THE MAIN MAN-
UAL SHUT-OFF VALVE AND SHUT OFF ALL POWER TO
THE UNIT.
1.
Remove the two (2) #8 screws holding each burner in
place.
2.
Remove the burner assembly from the manifold assem-
bly by moving the burner assembly forward, turn at an
angle and pull back.
3.
Burners are now accessible for service.
PILOT INSTRUCTIONS
FIGURE 17 - PROPER FLAME ADJUSTMENT
To adjust the pilot flame:
1.
Remove the pilot adjustment cover screw.
2.
Adjust the pilot adjustment screw to achieve the proper
pilot flame.
3.
The pilot flame should envelope 3/8” of the end of the
flame sensor and not contain any yellow color, see Fig-
ure 17.
4.
Replace the pilot adjustment cover screw after the pilot
flame is set.
To check, adjust or remove the pilot assembly, CLOSE THE
MAIN MANUAL SHUT-OFF VALVE AND SHUT OFF ALL
POWER TO THE UNIT.
1.
Disconnect the wiring from the control board to the pilot
assembly.
2.
Remove the two (2) #8 screws holding the pilot assem-
bly in place.
3.
Remove the pilot assembly.
ADJUSTMENT OF TEMPERATURE RISE
After about 20 minutes of high heat operation, determine the
furnace temperature rise. Take readings of both the return air
and the heated air in the ducts about six feet from the furnace
where they will not be affected by radiant heat.
The temperature rise (or temperature difference between the
return air and the heated air from the furnace) must lie within
the range shown on the rating plate and the data in Tables 3
thru 6.
After the temperature rise has been determined, the CFM can
be calculated as follows:
DIRECT DRIVE BLOWER
All units have multi speed direct drive blower motors. Refer to
the unit wiring diagram for the desired cooling and heating
speed.
8
3
"
Pilot
Spark Ignitor
Flame Sensor
min.
Degrees F Temp Rise
BTUH Output
1.08
CFM
------------------------------------
=
OR
CFM
BTUH Output
1.08
Degrees F Temp Rise
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=
