28
INSTALLATION CONSIDERATIONS
T
WINNING
Using the “TWIN” terminals and proper wiring enables two
DM96VE furnaces of the same model and size to be twinned.
Twinning allows simultaneous operation of two furnaces and
forces the indoor blower motors of each furnace to operate
synchronously into a common duct system. Using the twin-
ning function will require only field installed wiring with no
external kits or parts.
The staging DIP switches and speed tap DIP switches must
be set the same on both furnaces.
NOTE: Each furnace must be connected to its own 115 VAC
power supply. The L1 connection toeach furnace must be in
phase (connected to circuit breakers on the same 115 VAC
service panel phase leg). To verify that the furnaces are in
phase, check from L1 to L1 on each furnace with a voltme-
ter. If the furnaces are in phase, the voltage between both
furnaces will be
ZERO
.
Room
Thermostat
Y2
Y
W
W2
R
G
C
Ylo
Y
W
W2
R
G
C
Ylo
Y
W
W2
R
G
C
Furnace 1
Furnace 2
CIRCULATOR BLOWER SPEED ADJUSTMENT
WARNING
HIGH
VOLTAGE
D
ISCONNECT
ALL
POWER BEFOR CHANGING SPEED TAPS.
M
ULTIPLE POWER SOURCES MAY BE PRESENT.
F
AILURE TO DO
SO MAY CAUSE PROPERTY DAMAGE, PERSONAL INJURY OR DEATH.
This furnace is equipped with a multi-speed ECM motor.
Two wiring harnesses connect the motor to the integrated
control board and furnace power supply. The line voltage
(115 VAC) power supply to the motor is constant and not
switched by the control board. Motor operation is also de-
pendent on a pulsating DC signal on one of the four speed
taps on the motor. The airflow tables for heating and cooling
speeds show the relationship between airflow (CFM) and
external static pressure for each size furnace.
T
O
AVOID
PERSONAL
INJURY
OR
DEATH
DUE
TO
ELECTRICAL
SHOCK
,
TURN
OFF
POWER
TO
THE
FURNACE
BEFORE
CHANGING
SPEED
TAPS
.
WARNING
C
IRCULATOR
B
LOWER
S
PEED
F
ACTS
1. Motor Speed Tap wiring must remain in factory position
on the control board and motor.
2. There are 4 speed Tap wires to the motor T1, T2, T3, T4.
3. There are 5 speeds available, depending on DIP switch
settings and found in air flow table for each size furnace.
4. T1 terminal is always energized for Low Heat / Constant
Fan speed.
5. T2 terminal is always energized for High Heat speed.
6. T3 terminal is always energized in Low Cooling.
7. T4 terminal is always energized in High Cooling.
8. Heating input (W1/ W2) always has priority over all other
thermostat input.
9. Cooling input (YLo/ Y) has priority over continuous fan
input.
10. Continuous fan input (G) has lowest priority.
*The blower speed wiring connections must remain in
factory position
.
Refer to the air flow table for your specific model furnace.
If a cooling or heat pump condensing unit is being used in
conjunction with this furnace, the three DIP switches in S2
are used to select the proper cooling speeds to match the
outdoor unit size. Typical CFM requirements are 400 CFM /
Ton.
1. Turn OFF power to the furnace.
2. Select the cooling blower speeds that match the instal-
lation requirements from the airflow table in this manual
or the Installation Manual, If factory cooling speeds do
not match the installation requirements, the dip switch
settings must be changed from factory position
3. Turn ON power to furnace.
4. Verify proper temperature rise in heat modes and CFM
in cooling modes
CIRCULATING AIR AND FILTERS DUCTWORK - AIR
FLOW
Duct systems and register sizes must be properly designed
for the C.F.M. and external static pressure rating of the fur-
nace. Ductwork should be designed in accordance with the
recommended methods of "Air Conditioning Contractors of
America" manual D.
A duct system should be installed in accordance with Stan-
dards of the National Board of Fire Underwriters for the In-
stallation of Air Conditioning, Warm Air Heating and Venti-
lating Systems, Pamphlets No. 90A and 90B.
A return air filter is not supplied with the furnace. The in-
staller must supply a means of filtering all of the return air.
Filter(s) shall comply with UL900 or CAN/ULC-S111 Stan-
dards. If the furnace is installed without filters, and is not
covered by the warranty.
