Accessory Connections; Typical Twinned Furnace Application; Twinning And Staging - Unitary products group GY8S*UH Installation Manual

166753-UIM-C-0706

ACCESSORY CONNECTIONS

ACCESSORY CONNECTIONS ACCESSORY CONNECTIONS ACCESSORY CONNECTIONS
The furnace control will allow power-switching control of various acces-
sories. Refer to Figure 12, for connection details.
HUM. HOT
BLK
115 VOLT
WHT
HUMIDIFER
EAC HOT
115 VOLT
BLK
ELECTRONIC
WHT
AIR CLEANER
FIGURE 11: Accessory Connections
ELECTRONIC AIR CLEANER CONNECTION ELECTRONIC AIR CLEANER CONNECTION
ELECTRONIC AIR CLEANER CONNECTION ELECTRONIC AIR CLEANER CONNECTION
Two 1/4" (6.4 mm) spade terminals (EAC and EAC N) for electronic air
cleaner connections are located on the control board. The terminals
provide 115 VAC (1.0 amp maximum) during circulating blower opera-
tion.
HUMIDIFIER CONNECTION HUMIDIFIER CONNECTION HUMIDIFIER CONNECTION HUMIDIFIER CONNECTION
Two 1/4" (0.64 cm) spade terminals (HUM and HUM N) for humidifier
connections are located on the control board. The terminals provide 115
VAC (1.0 amp maximum) during heating system operation.
SECTION VI: TWINNING AND STAGING SECTION VI: TWINNING AND STAGING SECTION VI: TWINNING AND STAGING SECTION VI: TWINNING AND STAGING
NOTE: There are two different integrated control modules that can be
used on these models. They are part # 031-01933-000 and 031-01267-
001.
You can twin two 031-01933-000 integrated control modules or two
031-01267-001 integrated control modules. You cannot twin one 031-
01933-000 integrated control module and one 031-01267-001 inte-
grated control module. The two integrated control modules do not com-
municate with each other so they will not work in a twinning application.
In applications where more heating capacity or more airflow capacity is
needed than what one furnace can deliver, twinning can be used to
make two furnaces operate in tandem. When two furnaces are installed
using the same duct system, it is very important that the two furnace cir-
culating air blowers operate in unison. If one blower starts before the
second blower, the duct system will become pressurized and the blower
on the second furnace will turn backwards causing the second furnace
to overheat, resulting in damage to the furnace. Twinning is used to
make two furnaces operate in tandem, using one duct system, one
room thermostat and causing both furnaces to turn on and off simulta-
neously.
Before installing the relay and wiring, disconnect electrical power to
both furnaces. Failure to cut power could result in electrical shock
or equipment damage.
The relay must not be installed in any location where it could be
exposed to water. If the relay has been exposed to water in any
way, it must not be used.
12
EAC
SWITCHED
HUM CIRCUITS
NEUTRALS
TWINNING DUCT SYSTEM TWINNING DUCT SYSTEM TWINNING DUCT SYSTEM TWINNING DUCT SYSTEM
Twinned furnaces must only be applied on a common duct system. A
single air supply plenum must be used for both furnaces and coil(s).
Separate plenums and supply ducts systems cannot be utilized. A sin-
gle return air plenum, common to both furnaces must be used. It is sug-
gested that a return platform be utilized, with bottom air entrance into
each furnace. If a side entrance return system is used, the common
return duct must be divided equally so as to supply each furnace with
an equal amount of return air.
Both furnaces must be identical models in both heating capacity and
CFM capacity. Both furnaces must be operated on the same motor
speed tap. See typical application, Figure 13.
If furnace staging is desired with two single stage furnaces on a com-
mon duct, where the gas burner on the first furnace operates on W1
and the gas burner on the second furnace operates on W2, then the
use of an air-mixing device in the plenum to mix the air from both fur-
naces is strongly recommended. The mixing device must be installed
before any ducts that supply air to occupied spaces. Twinning causes
both indoor fans to operate simultaneously. If a mixing device is not
used, any ducts that are connected down stream from the furnace that
operates on W2, will be supplying cold air in the Heating mode to the
occupied spaces unless W2 is energized.
VENT PIPE
ELECTRICAL
SUPPLY
FIGURE 12: Typical Twinned Furnace Application
IMPORTANT: When two furnaces are twinned, typical system total air-
flow will be approximately 85% of additive individual furnaces, i.e., two
2000 CFM units will yield a total 3400 CFM.
If a return duct is connected to only one furnace (with a connection
between the two furnaces) an imbalance in the airflow will occur
and the furnace furthest from the return plenum will overheat.
GAS PIPING GAS PIPING GAS PIPING GAS PIPING
Furnace gas supplies must be provided as specified with these instruc-
tions. Since the furnaces are side by side, with no space between, gas
supplies must enter on the right and left respectively. All gas piping
must be in accordance with the national fuel gas code, ANSI Z223.1,
latest edition, and/or all local code or utility requirements.
GAS SUPPLY
(both sides)
1 COIL FOR
EACH FURNACE
SUPPLY
AIR
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