5750156-UIM-B-0919
18
Johnson Controls Ducted Systems
START-UP
Prestart Check List
Complete the following checks before starting the unit.
• Check the type of gas being supplied. Ensure that it is the same as
listed on the unit nameplate.
• Make sure that the vent outlet air hood and air intake hood have
been properly installed.
Operating Instructions
1.
STOP! Read the information on the unit safety label.
2.
Set the thermostat to the OFF position.
3.
Turn off all electrical power to the unit.
4.
DO NOT try to light the burners by hand. This appliance is
equipped with an ignition device which automatically lights the
burners.
5.
Remove the access panel.
6.
Turn the gas valve switch to the OFF position.
7.
Wait 5 minutes to clear out any gas. If you then smell gas, STOP!
Follow B in the information on the unit safety label. If you don't
smell gas, go to the next step.
8.
Turn the gas valve switch to the ON position.
9.
Replace the control access panel.
10. Turn on all electric power to the unit.
11. Set the thermostat to the required setting.
12. If the unit does not operate, follow the instructions in the Turning Off
Gas To Unit section and call your service technician or gas supplier.
Turning Off Gas To Unit
1.
Set the thermostat to the OFF position.
2.
Turn off all electric power to the appliance if service is to be per-
formed.
3.
Remove the control access panel.
4.
Turn the gas valve switch to the OFF position. DO NOT FORCE.
5.
Replace the control access panel.
Post Start Check List
After the entire control circuit has been energized and the heating sec-
tion is operating, make the following checks:
• Check for gas leaks in the unit piping as well as the supply piping.
• Check for correct manifold gas pressures. See the CHECKING
GAS HEAT INPUT section.
• Check the supply gas pressure. It must be within the limits shown
on rating nameplate. Supply pressure must be checked with all
gas appliances in the building at full fire. At no time must the
standby gas line pressure exceed 13.5 in., nor the operating pres-
sure drop below 4.5 in. for natural gas units. If gas pressure is out-
side these limits, contact the local gas utility for corrective action.
ADJUSTMENT OF MANIFOLD GAS PRESSURE AND
INPUT RATE
Inlet and manifold gas pressure may be measured by connecting the U
tube manometer to the gas valve with a piece of tubing. Follow the
appropriate section in the instructions below. See Figure 9 for the loca-
tions of the pressure ports on the gas valve.
Turn gas off at the ball valve or gas cock on gas supply line
before the gas valve. Find the pressure ports on the gas
valve marked Out P and In P.
1.
The manifold pressure must be taken at the port marked OUT P.
2.
The gas line pressure must be taken at the port marked IN P.
3.
Using a 3/32 in. (2.4 mm) hex head wrench, loosen the set screw
by turning it one turn counter clockwise. DO NOT REMOVE THE
SET SCREW FROM THE PRESSURE PORT.
Read the inlet gas pressure
Connect the positive side of the manometer to the IN P Tap on the gas
valve. Do not connect any tubing to the negative side of the manometer,
because it references atmospheric pressure. See Figures 9
and 10 for
connection details.
1.
Turn gas and electrical supplies on and follow the operating instruc-
tions to place the unit back in operation.
2.
Once the correct gas inlet pressure has been established (see
Table 16), turn the gas valve to OFF and turn the electrical supply
switch to OFF. Remove the flexible tubing from the gas valve pres-
sure tap and tighten the pressure tap plug using the 3/32 in. (2.4
mm) hex head wrench.
3.
Turn the electrical and gas supplies back on, and with the burners
in operation, check for gas leakage around the gas valve pressure
port using an approved non-corrosive gas leak detection fluid, or
other non-flammable leak detection methods.
Read the manifold gas pressure
Connect the positive side of the manometer to the OUT P Tap on the
gas valve. Do not connect any tubing to the negative side of the
manometer, because it references atmospheric pressure. See Figures
9 and 10 for connection details.
1.
See Figure 9 for location of pressure regulator adjustment cap and
adjustment screws on main gas valve.
2.
Turn gas and electrical supplies on and follow the operating instruc-
tions to place the unit back in operation.
3.
Adjust manifold pressure by adjusting gas valve regulator screw for
the appropriate gas per Table 17.
Table 16:
Inlet Gas Pressure Range
INLET GAS PRESSURE RANGE
Natural Gas
Propane (LP)
Minimum
4.5 in. W.C. (1.12 kPa)
8.0 in. W.C. (1.99 kPa)
Maximum
10.5 in. W.C. (2.61 kPa) 13.0 in. W.C. (3.24 kPa).
IMPORTANT:
The inlet gas pressure operating range table specifies
what the minimum and maximum gas line pressures must be for the
furnace to operate correctly. The gas line pressure
MUST BE
a mini-
mum of:
•
7 in. W.C. (1.74 kPa) for Natural Gas
•
11 in. W.C. (2.74 kPa) for Propane (LP) Gas
This is in order to obtain the BTU input specified on the rating plate
and/or the nominal manifold pressure specified in these instructions
and on the rating plate.
IMPORTANT:
The cap for the pressure regulator must be removed
entirely to gain access to the adjustment screw. Loosening or tighten-
ing the cap does not adjust the flow of gas.
NOTICE
The regulated outlet pressure has been calibrated at the factory.
Additional pressure adjustment should not be necessary. If adjust-
ment is necessary, set to the following specifications. After adjust-
ment, check for gas leakage.
Table 17:
Nominal Manifold Pressure
NOMINAL MANIFOLD PRESSURE
Natural Gas
3.5 in. W.C. (0.87 kPa)
Propane (LP) Gas
10.0 in. W.C. (2.488 kPa)
