S. M. • Rev. 6-93 • • ©Honeywell Inc. 1993 • Form Number 69-0580—2
M3375
T874A,D Zone Thermostats/
Q674B,D,E Subbases
TABLE 2—THERMOSTAT/SUBBASE SPECIFICATIONS.
Thermostat/
Anticipator Range (A)
Thermostat/Subbase
Switching
Subbase
Heating
Cooling
Order Number
a
System
Fan
Color
(Adj.)
(Fixed)
T874A1465/Q674B1471 HEAT-OFF-COOL
ON-AUTO
White/Gray
Stg. 1—
Stg. 1—
T874A1465/Q674D1123 None
None
White/Gray
0.1 to 1.2
0 to 1.5
T874A1465/Q674E1379 HEAT-OFF-COOL-AUTO ON-AUTO
White/Gray
T874D1801/Q674B1463 HEAT-OFF-COOL
ON-AUTO
Beige/Brown
Stg. 1—
Stg. 1—
T874D1827/Q674B1471 HEAT-OFF-COOL
ON-AUTO
White/Gray
0.1 to 1.2;
0 to 1.2;
T874D1801/Q674D1115 None
None
Beige/Brown
Stg. 2—
Stg. 2—
T874D1827/Q674D1123 None
None
White/Gray
0.1 to 1.0.
0 to 1.0.
T874D1827/Q674E1379 HEAT-OFF-COOL-AUTO ON-AUTO
White/Gray
a
Subbase not included with thermostat; order separately.
Operation
On a 2-heat thermostat, the two stages of heat make
sequentially as the temperature drops. Make refers to the
mercury switch initiating a call for heat or cool.
There are about 2
°
F [1
°
C] between stages so that the
second stage makes only when the first stage cannot
handle the load. This is the interstage differential.
Recycling Notice
This control contains mercury in a sealed tube. Do not
place control in the trash at the end of its useful life.
If this control is replacing a control that contains mercury
in a sealed tube, do not place your old control in the trash.
Contact your local waste management authority for
instructions regarding recycling and the proper disposal of
this control, or of an old control containing mercury in a
sealed tube.
If you have questions, call Honeywell at 1-800-468-1502.
M3375
Installation Instructions for the Trained Service Technician.
TABLE 1—THERMOSTAT/SUBBASE AND SYSTEM COMPATIBILITY.
Thermostat/
Application
Subbase Model
Number
a
Mini-Zone
Mabs II, Mabs II-L
Mabs XX
Stages
T874A/Q674B
Zone 1; conventional
Zone 1; conventional
Any zone; conventional heat-cool. Single-stage
heat-cool.
heat-cool.
T874A/Q674D
Zones other than zone 1;
Zones other than zone 1;
Not applicable
Single-stage
conventional heat-cool.
conventional heat-cool.
T874A/Q674E
Not applicable
Not applicable
Any zone; conventional heat-cool. Single-stage
T874D/Q674B
Not applicable
Zone 1; conventional
Any zone; conventional heat-cool. Multistage
heat-cool.
T874D/Q674D
Not applicable
Zones other than zone 1;
Not applicable
Multistage
conventional heat-cool
and heat pump.
T874D/Q674E
Not applicable
Not applicable
Any zone; conventional heat-cool. Multistage
a
Subbase not included with thermostat; order separately.
Application
These T874A,D Zone Thermostats and Q674B,D,E
Subbases provide 24 to 30 Vac temperature control in
Honeywell Trol-A-Temp heating/cooling zone systems.
See Table 1 for thermostat/subbase and system compatibil-
ity; see Table 2 for thermostat specifications. For complete
Honeywell Trol-A-Temp System specification and appli-
cation information, refer to the system specification in-
cluded with the control panel.
Summary of Contents for TROL-A-TEMP Q674B
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