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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
60-2485—8 6
Optional Specifications (Q674 Only):
Models available with up to four LEDs; for example, LEDs can
show EM. HT, AUX. HT, SERVICE, CHECK, FILTER, and
LOCKOUT. See Fig. 3.
System switching marked HEAT-OFF/RESET-COOL for sys-
tems requiring impedance relay reset. Available on Q674B
only.
G terminal isolated on heating to provide fan relay operation
from external low voltage fan switch (Q674B only).
Auto fan operation on both heat and cool.
L terminal is used for system monitoring devices.
Common R terminal for heating/cooling.
Changeover in cool or heat mode for heat pumps.
Auto fan in EM.HT. for heat pumps.
Subbase Accessory: 193121A Adapter Plate Assembly for
mounting on vertical outlet box. Assembly includes adapter
ring and cover plate. Use to cover wall marks from
replaced thermostat.
Fig. 3. Heating, cooling levers and system LED indicators.
Q674E—Standard and TRADELINE. Q672E Standard OFF-HEAT-AUTO-
COOL
AUTO-ON T874A-D
Q674F—Two LED models.
— EM.HT. light.
Q672F Heat Pump OFF-EM.HT.-HEAT-
AUTO-COOL
AUTO-ON T874C,D,G,N,S
— Provision for AUTO fan operation in
EM.HT.
OFF-COOL-AUTO-
HEAT-EM.HT.
AUTO-ON
Q674G—O and B terminals. Q672G Standard OFF-AUTO None T874A-F
Q674J—Provision for AUTO fan operation Q672J Heat Pump EM.HT.-AUTO-OFF AUTO-ON T874A,D,G,J
in EM.HT. EM.HT.-ON-OFF AUTO-ON
— Provision for outdoor thermistor. SUPL.HT.-ON-OFF AUTO-ON
Q674K—Standard. Q672K Standard OFF-HEAT-AUTO-
COOL
None T874F
OFF-WOOD-WOOD/
OIL-OIL
None
Q674L—Provision for AUTO fan operation in
EM.HT.
Q672L Heat Pump EM.HT.-HEAT-OFF-
COOL
AUTO-ON T874R,W
— Indicator LEDs. SUPL.HT.-HEAT-
OFF-COOL
AUTO-ON
Q674N—Standard. Q672N Evaporative
Cooler
EVAP-COOL-OFF-
HEAT
AUTO-ON T874C
Q674P—Standard. Q672P Heat Pump SUPL.HT.-HEAT-
COOL
AUTO-ON T874G
Q674Q—Standard. None Fan Coil HEAT-OFF-COOL LO-MED-HI-
ON
T874A
Q674R—Standard.
— International symbols.
None Fan Coil OFF-COOL LO-HI-
CONT.
T874V
Q674S—Indicator LED. None Standard HEAT-COOL None T874C
T874 Thermostat with
One Setpoint Lever
Q674 Subbase
with Four LEDs
T874 Thermostat with
Separate
Heatin
g
and Coolin
g
Levers