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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
5 60-2485—8
Models:
See Table 4.
Electrical Ratings:
Switch Contacts: 2.5A at 30 Vac (7.5A inrush).
LED Lights (Optional): 30 Vac.
Switches: Two slide switches (one switch on Q674G and K;
no switches on Q674D) operated by levers. Switch position
is shown on scaleplate.
Mounting: Designed to mount horizontally on an outlet box
or the wall. Adapter plate assembly available for mounting
on a vertical outlet box (see Subbase Accessory).
Finish: Dark brown or gray.
Dimensions in in. (mm): 3-1/2 (89)height; 5-5/8 (143) width;
5/16 (8) depth. See Fig. 1.
Table 4. Q674 Subbase Specifications.
— Fast cycling. Electric Heat 0.12-
0.6A
0.12-
0.6A
T874G—Heat pump, cool
changeover, with fast cycling.
T872G Heat Pump or
Standard
21
1
b
0-1.0A
c
0.1-1.2A 0-1.0A —
— Fixed anticipator for H2. 0.1-1.5A
— Fast cycling. 0.12-
0.6A
T874H—Use with Q674C. T872H Heat Pump or
Standard
11
1
b
0-1.0A
c
—0-1.0A—
T874J—Heat pump. None Heat Pump 2 1
2
d
0-1.0A
e
0-1.5A
c
0-1.0A
c
—
T874K—Heat pump. None Heat Pump 2 1
1
b
0.1-1.2A
0-1.5A
c
0-1.5A —
T874L—Heat pump. None Heat Pump 2 1 — 0.1-1.2A 0.1-1.2A 0-1.5A —
T874N—Heat pump, heat
changeover.
T872N Heat Pump 2 1
1
b
0.1-1.2A 0.1-1.2A 0-1.0A —
T874P—Heat pump. None Heat Pump 2 1 — 0.1-1.2A 0.1-1.2A 0-1.5A —
T874Q—Night setback heating. T872Q Standard
1
e
— — 0.1-1.2A — — —
T874R—Heat pump. T872R
Heat Pump
f
21—
0-1.5A
c
0.1-1.2A 0-1.5A —
T874S—Two-speed compressor heat
pump.
None Heat Pump 2 2
1
g
0-1.2A
c
0-1.2A
c
0-1.2A 0-1.0A
T874V—Standard. None Standard — 1 — — — 0-1.5A —
T874W—Heat pump and standard.
— Night setback heating.
T872W Heat Pump or
Standard
32—
0-1.2A
b
0-1.2A
c,d
0-1.2A 0-1.0A
a
Department of Defense.
b
Changeover stage operates with heating.
c
Fixed voltage type anticipation.
d
Changeover stage operates with heating; a secondary changeover is provided in cooling switch.
e
Provides night setback used with standard T874 and timer-operated remote switching.
f
Manual changeover stage—use Q674B,L subbase.
g
Changeover stage operates with cooling.Q674 Subbases
Models and Options Replaces Application
Switch Positions
Use WithSystem Fan
Q674A—Standard and TRADELINE®.
— Indicator LEDs.
Q672A Standard HEAT-AUTO-COOL AUTO-ON T874A-D
Q674B—Standard and TRADELINE. Q672B Standard HEAT-OFF-COOL AUTO-ON T874A-D
— Provision for fan relay operation from Heat Pump T874G,H,L,R
external fan switch (isolate G terminal). OVERRIDE-HEAT- AUTO-ON T874P
— Indicator LEDs. OFF-COOL
Q674C—Standard and TRADELINE. Q672C Standard OFF-AUTO AUTO-ON T874A-H,W
— Indicator LEDs. Heat Pump OVERRIDE-AUTO- AUTO-ON T874K,L,N
OFF T874P
Q674D—Standard and TRADELINE.
— For use when subbase switching is not
required.
Q672D Standard None None T874A-F