J962V Installation Manual

22
Dehumidification Options
The motor control board (Figure 24 (page 30)) has a
DEHUM connection that allows the system to increase the
amount of humidity that is removed from the circulating air.
This is accomplished by reducing the CFM and allowing
the cooling coil to become colder. This will only occur
when there is a call for cooling. There are many ways
that this can be electrically wired:
• If the room thermostat incorporates a humidity sensor
and DEHUM output, connect the DEHUM on the
thermostat to the DEHUM terminal on the motor control
board. See Figure 20 (page 23).
• If using a separate humidistat, connect the DEHUM
& R terminals on the humidistat to the DEHUM & R
terminals on the motor control board. See Figure 24. In
this option, the DEHUM output of the humidistat must
be set to be normally open and closed when there is a
call for humidification.
• If a humidistat is not available, it is an acceptable
option to connect the R & DEHUM via a field supplied
normally open relay. See Figure 21 (page 23). The R
& DEHUM terminals should be connected across the
normally open relay terminals. The O (B) & C terminals
should then be connected across the relay coil. This
option causes the blower to run at a reduced CFM for
10 minutes after a call for cooling.
Heat Anticipator
Set the heat anticipator according to the instructions
supplied by the thermostat manufacturer. To determine
the heat anticipator setting:
1. Add the current draw of the system components; or
2. Measure the current flow on the thermostat R & W
circuit after the circulating blower motor has started.
START-UP & ADJUSTMENTS
Pre-Start Check List
√ Verify the polarity of the connections are correct, the
line voltage power leads are securely connected and
the furnace is properly grounded.
√ Verify that all needed thermostat wires are securely
connected to the correct leads on the terminal strip of
the circuit board. See Figure 17 (page 21), Figure 18
(page 21)
, & Figure 19 (page 21).
√ Verify the gas line service pressure does not exceed
10.0 inches of water column, and is not less than 4.5
inches W.C. for natural gas. For LP gas the line service
pressure must not exceed 14 in. W.C., and must not
be less than 11.0 in. W.C.
√ Verify the roll-out and manual reset switch is closed.
If necessary, press the button to reset the switch. DO
NOT install a jumper wire across a switch to defeat
its function. If a switch reopens on start-up, DO NOT
reset the switch without identifying and correcting the
fault condition.
√ Verify the blower door is in place, closing the door switch
in the line voltage circuit.
√ Verify the gas line has been purged and all connections
are leak free.
then stage up to HIGH fire, until the heating load is met.
See Figure 17 and the Low Voltage Connection section
on page 21.
The autostaging option on the furnace control board is
selected using the autostage jumper located near the
thermostat terminal block. See Figure 25 (page 30).
When the autostage jumper is moved from OFF to ON,
the following occurs during a call for heat:
Setting the Autostage jumper in the ON position signals
the control to utilize a 10 minute delay between LOW fire
and HIGH fire when a call for heat is supplied via 24V
signal to W1. This setting is the same as jumping R to W2.
NOTE: If the autostage jumper is in the ON position and
a W1 demand is present when power is applied to the
furnace, the first heat cycle will run in second stage heat
with no autostaging. After the first cycle, the furnace will
resume normal autostaging operation. DO NOT jump
W1 & W2 together while the autostage jumper is in
the ON position.
Autostaging for Two-Stage Thermostats
The Autostage setting on the furnace control board Figure
25 (page 30)
is disabled when shipped from the factory.
This feature will be not used when paired with a two-stage
thermostat. The autostage jumper setting (P7) must be
kept on OFF to allow the thermostat to adjust stages.
Blower Speed Configuration
Two-stage furnaces use high efficiency circulating air
motors that come in two variations and both are controlled
differently. The fixed speed furnace uses a motor control
board that maintains constant motor torque, while the
variable speed furnace uses a motor control board that
maintains constant CFM airflow. Both boards use the
same furnace control board.
Fixed Speed Blower Applications
The fixed speed motor control board (Figure 24 (page 30))
contains a set of dip switches for setting the blower speed.
Use pins 1 to 4 to set the blower speed for heating and
pins 5 to 8 to set the speed for cooling. To determine the
appropriate switch settings for your installation, see the
separate blower table attachment.
For thermostats with a dehumidifier output, use a field
supplied wire to connect the thermostat’s dehumidifier
output to the terminal marked DEHUM. The thermostat
should be set so that the DEHUM output should be high
(positive) when dehumidification is needed. See also
Dehumidification Options section.
CAUTION:
The terminal marked “Y1_IN” on the variable
speed motor control board is not an output to
drive the outdoor unit. DO NOT connect Y1_IN
on the motor control board to the outdoor unit.