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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
60-2485—86
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 Fi
g
. 3.
S
y
stem switchin
g
marked HEAT-OFF/RESET-COOL for s
y
s-
tems re
q
uirin
g
impedance rela
y
reset. Available on Q674B
onl
y
.
G terminal isolated on heatin
g
to provide fan rela
y
operation
from external low volta
g
e fan switch
(
Q674B onl
y)
.
Auto fan operation on both heat and cool.
L terminal is used for s
y
stem monitorin
g
devices.
Common R terminal for heatin
g
/coolin
g
.
Chan
g
eover in cool or heat mode for heat pumps.
Auto fan in EM.HT. for heat pumps.
Subbase Accessory:
193121A Adapter Plate Assembl
y
for
mountin
g
on vertical outlet box. Assembl
y
includes adapter
rin
g
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. li
g
ht.
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 s
y
mbols.
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