1183746-UIM-B-0215
Johnson Controls Unitary Products
17
COOLING SEQUENCE OF OPERATIONS
When the thermostat calls for COOL, the thermostat terminals G and Y
are energized, which signals the compressor, outdoor fan and indoor
blower to run.
With a call for Y, the circulating fan is energized at cooling speed.
When the thermostat is satisfied, terminals G and Y are de-energized,
de-energizing the compressor and outdoor fan.
After a cool fan off delay timing of 30 seconds, the circulating fan is de-
energized.
Safety Controls
The control circuit includes the following safety controls:
High Pressure Switch (HP) - This switch protects against excessive dis-
charge pressures due to a blocked condenser coil or a condenser
motor failure (opens at 650 ± 25 psig and closes at 450 ± 25 psig).
The above pressure switches are specifically designed to operate with
R-410A systems. R-22 pressure switches must not be used as replace-
ments for the R-410A pressure switches.
Circulating Fan
When the thermostat calls for FAN, the thermostat terminal G is ener-
gized signaling the circulating fan to run at the G-Speed airflow.
If a call for COOL occurs (Y), the circulating fan switches to run at the Y-
Speed airflow.
If a call for HEAT occurs (W), the circulating fan switches to W-Speed
after a 30 second delay.
When the thermostat ends the call for FAN, the thermostat terminal G is
de-energized, de-energizing the circulating fan.
START-UP
Prestart Check List
Complete the following checks before starting the unit.
1.
Check the type of gas being supplied. Be sure that it is the same as
listed on the unit nameplate.
2.
Make sure that the vent outlet air hood and air intake hood has
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 five (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 desired setting.
12. If the unit will not operate, follow the instructions To Turn Off Gas To
Appliance and call your service technician or gas supplier.
To Turn 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:
1.
Check for gas leaks in the unit piping as well as the supply piping.
2.
Check for correct manifold gas pressures. See Checking Gas Input.
3.
Check the supply gas pressure. It must be within the limits shown
on rating nameplate. Supply pressure should be checked with all
gas appliances in the building at full fire. At no time should the
standby gas line pressure exceed 13.5", nor the operating pressure
drop below 4.5" for natural gas units. If gas pressure is outside
these limits, contact the local gas utility for corrective action.
Manifold Gas Pressure Adjustment
Small adjustments to the gas flow may be made by turning the pressure
regulator adjusting screw on the automatic gas valve.
Refer to Figure 10.
Adjust as follows:
1.
Remove the cap from the valve body. See Figure 10 for location.
2.
To decrease the gas pressure, turn the adjusting screw counter-
clockwise.
3.
To increase the gas pressure, turn the adjusting screw clockwise.
Adjustment of Temperature Rise
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 six feet from the furnace where they will not be affected by radi-
ant 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 Table 6.
After the temperature rise has been determined, the CFM can be calcu-
lated as follows:
WARNING
The ability to properly perform maintenance on this equipment
requires certain expertise, mechanical skills, tools and equipment. If
you do not possess these, do not attempt to perform any mainte-
nance other than those procedures recommended in this Installation
Manual. Failure to heed this warning could result in serious injury
and possible damage to this equipment.
!
FIGURE 9:
Gas Valve
NOTICE
The correct manifold pressure for natural gas furnaces is 3.5 IWG.
The correct manifold pressure for propane (LP) is 10.0 IWG.
INLET
WRENCH
BOSS
INLET
PRESSURE
PORT
ON
OFF
ON/OFF SWITCH
(Shown in ON position)
MAIN REGULATOR
ADJUSTMENT
OUTLET
OUTLET
PRESSURE
PORT
VENT PORT
A0303-001
BTUH Output
1.08 x CFM
OR
CFM =
BTUH Output
Degrees F Temp Rise =
1.08 x Degrees F Temp Rise
