Nordyne *SA Upfl ow / Horizontal Installation Instructions Manual Download Page 20

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Figure 15. Low Voltage Field, Four-wire

Heating/Cooling Applications

RCY

G
W

STATUS

FLAME

GREEN

RED

180

COOL

HEA

120

90
60

YELLOW

BLOWER

OFF

DELAY

LO
W

HIGH

EA
C

XFMR

HUM

COM

SPEED

SELECT

3 AMP
FUSE

24V

NEUTRALS

ROOM

THERMOSTAT

A/C CONDENSING UNIT

CONDENSING UNIT
CONTROL BOX

EXPANSION PORT

(MOTOR CONNECTION)

FIELD WIRING
LOW VOLTAGE
CONNECTION

R
C
Y
G

NOTE: The “Y” terminal
on the control board
must be connected to the
thermostat for proper
cooling mode operation.

Connect

R & W

For Heating

Only

ELECTRONIC AIR CLEANER

MOTOR SPEED TAPS
(NOT USED)

HUMIDIFIER TAP

NEUTRAL LEADS

FA
N

Thermostat / Low Voltage Connections

• The furnace is designed to be controleed by a 24 VAC

thermostat. The thermostat’s wiring must comply with
the current provisions of the NEC (ANSI/NFPA 70) and
with applicable local codes having jurisdiction.

• The thermostat must be installed according to the

instructions supplied by the thermostat manufacturer.
Low voltage connections (24 VAC) from the thermostat
are wired to the terminal strip on the integrated control in
the furnace. Figure 15 contains the proper connections
for heating only (two-wire) and heating/cooling (four-
wire) applications. Recommended minimum wire gauge
for thermostat wiring is shown in Table 2 (page 19).

• The thermostat should be mounted about 5 feet

above the fl oor on an inside wall. DO NOT install the
thermostat on an outside wall or any other location
where its operation may be adversely affected by radiant
heat from fi replaces, sunlight, or lighting fi xtures, and
convective heat from warm air registers or electrical
appliances. Refer to the thermostat manufacturer’s
instruction sheet for detailed mounting information.

• The six pin terminal marked “Expansion Port” (Figure

15) is not used in the single stage furnace as shipped
from the factory. It is used for the furnace control board
to communicate to a fi xed speed or variable speed high
effi ciency motor that may be optionally installed. Please
contact your distributor for the proper upgrade motor
kit.

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 fl ow on the thermostat

R-W

circuit

after the circulating blower motor has started.

Twinning

Single stage furnaces are not supplied with a built-
in twinning capability. Other valuable features and
enhancements were made to the new control that made it
necessary to remove the twinning capability. For twinning
of single stage furnaces with PSC motors, a twinning kit
(920919) is available for purchase.

Please follow the

instructions provided with the kit.

If both single stage furnaces are upgraded to the fi xed
speed iSEER ™ blower, the twin terminal on the blower
control boards (Figure 16) may be used to twin the single
stage furnaces only if the following criteria are met:
• Both furnaces and motors must be the same size.
• Both motors must be on the same speed for cooling

and heating.

• Both furnaces must have a common return duct and

common supply plenum.

• Both furnaces must be the same phase and on the

same leg of power.

IMPORTANT NOTE: Furnaces equipped with variable
speed iSEER ™ motors may not be twinned under
any circumstances.

WARNING:

When servicing either twinned furnace, power
must be turned off on both furnaces. Failure to
comply may result in improper operation leading
to damage to the furnaces or personal injury!

For twinning of single stage furnaces equipped with
fi xed speed iSEER ™ blowers, refer to Figure 16 and the
following instructions:

1. Turn off all power to both furnaces.

2. Attach a wire between the two twin terminals on the

twinning control boards. Use fi eld supplied wire and
two 3/16” wire terminals.

FURNACE

THERMOSTAT

A/C

FSHE

TWIN TERMINAL

BOARD

UNIT

BOARD