272357-UUM-A-0407
6
Unitary Products Group
5.
1st and 2nd Stage called simultaneously
• The 1st stage call is processed as described in paragraph 1
above.
• Once Flame Rectification is established, 2nd Stage is entered
immediately as described in paragraph 2 above.
6.
1st and 2nd Stage satisfied simultaneously
• Both stages of the Gas Valve are de-energized.
• Flame Rectification is lost.
• The Inducer and Hum relays are de-energized after a 15-second
post purge.
• 30 seconds later the Control shifts the Blower from Heat High to
Heat Low.
• After the Blower-Off Delay Circuit is satisfied, the Blower and
EAC are de-energized.
7.
Manual Fan Operation
• With the thermostat in the Fan On position, a circuit is completed
between R and G of the Control.
• The Heat Low and EAC relays are energized by the Control.
8.
Call for Cooling
• The thermostat closes two circuits R to Y and R to G. Since the
Outdoor Unit is connected to Y and C at the Control, it is ener-
gized.
• The Cool and EAC relays are energized by the Control.
• A Blower-Off Delay Timing Circuit is energized by the call on Y.
9.
Cooling call satisfied
• The thermostat opens the R to Y and R to G circuits.
• The Outdoor Unit is de-energized.
• The 60-second, Blower-Off Delay, timing circuit is initiated.
• After 60 seconds, the Cool and EAC relays are de-energized.
10. Two-stage cooling. This furnace is equipped to handle a two-stage
AC unit.
•
The wall thermostat will energize the Y1 circuit for low cooling
and the Y2 circuit for high cooling.
ADJUSTMENT OF FAN CONTROL SETTINGS
Heating Indoor Fan Off Delay
Changing the blower delay jumper on the Furnace Control Board can
change the indoor fan “OFF” time delay. Refer to Figure 7 for the jumper
settings to obtain the desired fan OFF delay. The blower off delay must
be long enough to adequately cool the furnace, but not so long that cold
air is blown into the living space.
The blower on delay is fixed at 30 seconds and cannot be adjusted.
Continuous Blower Operation
Cooling/heating thermostats have a fan switch that has an ON and
AUTO position. In the ON position the thermostat circuit is completed
between terminals R and G. The motor will operate on the speed tap
selected on the Continuous Fan speed Jumper on the control board (HI
COOL, LO COOL, or HEAT pins).
Hot Surface Ignition System
TROUBLESHOOTING
The following visual checks should be made before troubleshooting:
1.
Check to see that the power to the furnace and the ignition control
module is ON.
2.
The manual shut-off valves in the gas line to the furnace must be
open.
3.
Make sure all wiring connections are secure.
4.
Review the sequence of operation. Start the system by setting the
thermostat above the room temperature. Observe the system’s
response. Then use the troubleshooting section in this manual to
check the system’s operation.
FIGURE 6:
Furnace Control Board
HI COOL
LO HEAT
EAC-H
L1
XFMR
NEUTRALS
HUM
60
90
120
180
BLOWER DELAY
Y/Y2
W2
R
G
C
Y1
LO COOL
REMOTE
SWITCH
FA
N
S
PEED
LO
COOL
LO
HEA
T
HI
COOL
W/W1
HI
HEA
T
W2
DELA
Y
OFF
10
MIN
15
MIN
20
MIN
HI HEAT
YELLOW - MED LOW
BLACK - HI
RED - LOW
BLUE - MED HI
CONTINUOUS
FAN SPEED
JUMPER
W1 - W2
DELAY
JUMPER
FAN OFF
ADJUSTMENT
JUMPER
HOT SURFACE IGNITION SYSTEM
Do not attempt to light this furnace by hand (with a
match or any other means). There may be a potential
shock hazard from the components of the hot surface
ignition system. The furnace can only be lit automatically
by its hot surface ignition system.
Never bypass any safety control to allow furnace opera-
tion. To do so will allow furnace to operate under poten-
tially hazardous conditions.
Do not try to repair controls. Replace defective controls
with UPG Source 1 Parts.
Never adjust pressure switch to allow furnace operation.
