Honeywell T874A,D Zone Thermostats/ Q674B,D,E Subbases Manual

Honeywell T874A,D Zone Thermostats Installation Instructions

Honeywell T874A,D Zone Thermostats Installation Instructions for the Trained Service Technician

Honeywell T874A,D Zone Thermostats 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 compatibility; see Table 2 for thermostat specifications. For complete Honeywell Trol-A-Temp System specification and application information, refer to the system specification included with the control panel.

TABLE 1—THERMOSTAT/SUBBASE AND SYSTEM COMPATIBILITY

Thermostat/

Subbase Model Numbera

Application

 

Stages

Mini-Zone

Mabs II, Mabs II-L

Mabs XX

T874A/Q674B

Zone 1; conventional heat-cool.

Zone 1; conventional heat-cool.

Any zone; conventional heat-cool.

Single-stage

T874A/Q674D

Zones other than zone 1;

conventional heat-cool.

Zones other than zone 1;

conventional heat-cool.

Not applicable

Single-stage

T874A/Q674E

Not applicable

Not applicable

Any zone; conventional heat-cool.

Single-stage

T874D/Q674B

Not applicable

Zone 1; conventional

heat-cool.

Any zone; conventional heat-cool.

Multistage

T874D/Q674D

Not applicable

Zones other than zone 1;

conventional heat-cool and heat pump.

Not applicable

Multistage

T874D/Q674E

Not applicable

Not applicable

Any zone; conventional heat-cool.

Multistage

a Subbase not included with thermostat; order separately. 

Thermostat/Subbase Order Numbera

Switching

Thermostat/

Subbase Color

Anticipator Range (A)

Heating

(Adj.)

Cooling

(Fixed)

System

Fan

T874A1465/Q674B1471

HEAT-OFF-COOL

ON-AUTO

White/Gray

Stg. 1—0.1 to 1.2

Stg. 1—0 to 1.5

T874A1465/Q674D1123

None

None

White/Gray

T874A1465/Q674E1379

HEAT-OFF-COOL-AUTO

ON-AUTO

White/Gray

T874D1801/Q674B1463

HEAT-OFF-COOL

ON-AUTO

Beige/Brown

Stg. 1—0.1 to 1.2;

Stg. 2—0.1 to 1.0.

Stg. 1—0 to 1.2;

Stg. 2—0 to 1.0.

T874D1827/Q674B1471

HEAT-OFF-COOL

ON-AUTO

White/Gray

T874D1801/Q674D1115

None

None

Beige/Brown

T874D1827/Q674D1123

None

None

White/Gray

T874D1827/Q674E1379

HEAT-OFF-COOL-AUTO

ON-AUTO

White/Gray

a Subbase not included with thermostat; order separately. 

Honeywell T874A,D Zone Thermostats 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.

Honeywell T874A,D Zone Thermostats Installation

WHEN INSTALLING THIS PRODUCT…

  1. Read these instructions carefully. Failure to follow them could damage the product or cause a hazardous condition.
  2. Check the ratings given in the instructions and on the product to make sure the product is suitable for your application.
  3. Installer must be a trained, experienced service technician.
  4. After installation is complete, check out product operation as provided in these instructions.

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 Honeywell T874A,D Zone Thermostats Manual