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5565604-BIM-B-1018
8.
If necessary, using a screwdriver, turn the first stage
adjustment screw (adjacent to the "LO" marking on the
valve) clockwise to increase manifold pressure or
counterclockwise to decrease manifold pressure. Be sure
not to under-fire the unit on first stage.
9.
Once pressure has been checked, replace the plastic cap
covering the HI and LO pressure adjustment screws.
NOTE: When using natural gas, the manifold pressure for
second stage (100% input) should be 3.5 IWG ± 0.3.
The manifold pressure for first stage (60% input) when
using natural gas should be 1.5 IWG ± 0.3.
Table 29: Gas Heat Stages
# of Burner Tubes
4
6
8
Adjustment Of Temperature Rise
The temperature rise (the difference of temperature between the
return air and the heated air from the furnace) must lie within the
range shown on the CSA rating plate and the data in Table 10.
After the temperature rise has been determined, the CFM can
be calculated as follows:
After about 20 minutes of operation, determine the furnace
temperature rise. Take readings of both the return air and the
heated air in the ducts (about 6 feet from the furnace) where
they will not be affected by radiant heat. Increase the blower
CFM to decrease the temperature rise; decrease the blower
CFM to increase the rise (See SUPPLY AIR DRIVE
ADJUSTMENT).
NOTE: Each gas heat exchanger size has a minimum
allowable CFM. Below this CFM, the limit will open.
Burners/Orifices Inspection/Servicing
Before checking or changing burners, pilot or orifices, CLOSE
MAIN MANUAL SHUT-OFF VALVE AND SHUT OFF ALL
POWER TO THE UNIT.
1.
Open the union fitting just upstream of the unit gas valve
and downstream from the main manual shut-off valve in
the gas supply line.
2.
Remove the screws holding each end of the manifold to the
manifold supports.
3.
Disconnect wiring to the gas valves and spark igniter's.
Remove the manifold & gas valve assembly. Orifices can
now be inspected and/or replaced.
To service burners, complete step 4.
4.
Remove the heat shield on top of the manifold supports.
Burners are now accessible for inspection and/or
replacement.
NOTE: Reverse the above procedure to replace the
assemblies.
60
2nd Stage Input
1st Stage Input
(100% Btuh)
(60% Btuh)
120,000
72,000
180,000
108,000
240,000
144,000
Make sure that burners are level and seat at the rear of the gas
orifice.
GAS
SUPPLY
PIPE
BURNER
BURNER BRACKET
IGNITOR
Figure 32: Typical Flame
HIGH & LOW GAS ADJUSTMENT
LO
HI
INLET
OFF
PRESSURE
TAP
INLET PRESSURE TAP
ON/OFF SWITCH
TERMINAL – C (COMMON)
TERMINAL – MP (1ST STAGE)
Figure 33: Typical Gas Valve
Charging The Unit
All ZJ units use Thermal Expansion Devices. Charge the unit to
nameplate charge.
Control Board Navigation Components
The following components are needed to access the control
points in the Smart Equipment™ control. Installation and
operation guides are available from your equipment dealer or
distributor.
1.
Local LCD on Unit Control Board.
2.
Mobile Access Portal (MAP) Gateway (Portable).
• Source 1 P/N S1-JC-MAP1810-OP
3.
MAP Gateway Quick Start Guide P/N 24-10737-16
4.
MAP Gateway Instruction P/N 24-10737-8
For more information on the Smart Equipment™ unit control board
navigation, refer to the Smart Equipment™ Quick Start Guide.
NOTE: For more in-depth sequence of operation of the Smart
Equipment™ control, refer to the Smart Equipment™
Controls Sequence of Operation Overview LIT-
12011950.
HEAT EXCHANGER TUBE
BURNER FLAME
(BLUE ONLY)
MATE-N-LOCK
CONNECTORS
MV
C
HI
ON
OUTLET
PRESSURE
TAP
OR
OUTLET PRESSURE TAP
REGULATOR COVER SCREWS
(REG. ADJ. BENEATH THESE
SCREWS)
TERMINAL – HI (2ND STAGE)
Johnson Controls Ducted Systems
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