T7984 A,B,C Electronic Modulating Control
Thermostats
PRODUCT DATA
These microprocessor-based thermostats provide proportional - integral (PI) individual room temperature control in zoned commercial Heating, Ventilating, and Air Conditioning systems such as hydronic heating and/ or cooling, pressure dependent VAV or by-pass box with or without terminal reheat.
The T7984 family provides modulating analog 2 to 10 Vdc control. Optional features include automatic heat/ cool changeover, reheat control, remote night setback with local timed override, and remote sensor on VAV models.
•PI (proportional and integral) control action provides accurate, stable room temperature control.
•T7984 models are used with Series 70 direct-coupled damper actuators such as ML7161 or ML7984, or with valve actuators such as ML7285, ML7421, VC7930 or M7410.
•All models feature user-friendly set point knob.
•All models feature output status LEDs for installer check-out.
•Locking cover and range stops are standard.
•Night setback models feature selection of two different offset temperatures and use central time switch control.
•Night setback models feature 2 1/2 hour local timed override.
•Heat/cool models feature automatic changeover with 3° or 5°F (1.5°C or 3°C) selectable Zero Energy Band (Z.E.B.) to meet requirements of ASHRAE 90.1
•Heat/cool models have installer-definable setpoint at midpoint of Z.E.B, at heating setpoint, or at cooling setpoint.
•Reheat models feature fast/slow response selection to match heating system dynamics.
•DIP switch selectable 75°F (24°C) high limit heating setpoint and low limit cooling setpoint.
•Horizontal and vertical covers included.
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Contents |
Application......................................................................... |
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Features ............................................................................ |
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Specifications .................................................................... |
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Ordering Information ......................................................... |
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Installation ......................................................................... |
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T7984A.............................................................................. |
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T7984B.............................................................................. |
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T7984C.............................................................................. |
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Checkout ........................................................................... |
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95C-10815-2
T7984 A,B,C ELECTRONIC MODULATING CONTROL THERMOSTATS
IMPORTANT
The specifications given in this publication do not include normal manufacturing tolerances. Therefore, this unit may not exactly match the listed specifications. Also, this product is tested and calibrated under closely controlled conditions, and some minor differences in performance can be expected if those conditions are changed.
MODELS: T7984A,B,C, 2 to 10 Vdc analog output
Table 1. Model Specifications
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Cool/Heat |
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Main |
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Changeover |
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Temperature |
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Mode Selection |
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Model |
Output 1 |
For Output 1 |
Output 2 |
Night Setback |
Sensor * |
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Input |
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T7984A |
Modulating 2 to |
Dry Contact or |
On/off |
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- |
Internal or |
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10 Vdc |
Sensor |
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remote |
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T7984B |
Modulating 2 to |
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Dry Contact |
Internal or |
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Jumper |
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10 Vdc |
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remote |
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T7984C |
Modulating 2 to |
Dry Contact or |
Modulating 2 to |
Dry Contact |
Internal or |
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10 Vdc |
Sensor |
10 Vdc |
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remote |
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* Remote sensor |
models are: |
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272845 Remote wall mount sensor |
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272847 Remote duct mount sensor |
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DIMENSIONS |
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* The maximum heating setpoint and minimum cooling |
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See Figure 1. |
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setpoint is electronically limited to 75°F [24°C]. |
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MOUNTING: Mounts to single-gang NEMA-standard 2"x 4" |
REMOTE SENSOR: 47 kΩ NTC thermistor [part nos. 272845 |
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electrical box, or directly to wall requires 1 1/8“ [35„mm] |
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and 272847]. |
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access hole for wiring. |
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ANALOG OUTPUT: 2 to 10 Vdc, 2 mA max. |
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WIRING: Four to eight 1/8“ screw terminals suitable for 2 no. |
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18 AWG [1 mm 2] wires each depending on model. |
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SWITCHED OUTPUT RATING: 0.5A running, 1.1A inrush, |
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POWER SUPPLY: 19-30 Vac, 50-60 Hz, 2 VA, Class 2. (Does |
24Vac, protected with selfresetting fuse. |
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not include actuator or reheat stage power requirements.) |
OPERATING PARAMETERS: See Table 2 for installer selections. |
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OPERATING AMBIENT: |
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APPROVALS: |
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32-104°F [0-40°C] at 5-95% Relative Humidity (non- |
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Designed for Class II low voltage installation only. |
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condensing). |
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Case and cover meets UL„94-5V flammability requirements, |
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ACCURACY: 1°F (0.6°C) PRECISION: ±1°F (0.5°C) tempera- |
and North American codes for line voltage thermostat |
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enclosures. |
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ture after stabilization. |
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Meets requirements of F.C.C. Part 15 Class B, IEC 801-3 for |
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PRECISION: ±1°F (0.5°C) temperature after stabilization. |
radio frequency interference. |
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SETPOINT RANGE: 55-90°F [13-32°C], T7984A. |
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ACCESSORIES: |
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Heating: 55-75°F [13-24°C], T7984B, C*. |
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272845 - Remote sensor (wall mounted). |
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272846 - Adaptor plate for 2-gang NEMA, or British 75 mm |
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Cooling: 75-90°F [24-32°C], T7984B, C*. |
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electrical box. |
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272847 - Remote sensor (duct mounted). |
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ORDERING INFORMATION
When purchasing replacement and modernization products from your TRADELINE® wholesaler or distributor, refer to the TRADELINE® Catalog or price sheets for complete ordering number.
If you have additional questions, need further information, or would like to comment on our products or services, please write or phone:
1.Your local Honeywell Automation and Control Products Sales Office (check white pages of your phone directory).
2.Honeywell Customer Care 1885 Douglas Drive North
Minneapolis, Minnesota 55422-4386
In Canada–Honeywell Limited/Honeywell Limitée, 35 Dynamic Drive, Scarborough, Ontario M1V 4Z9.
International Sales and Service Offices in all principal cities of the world. Manufacturing in Australia, Canada, Finland, France, Germany, Japan, Mexico, Netherlands, Spain, Taiwan, United Kingdom, U.S.A.
95C-10815–2 |
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T7984 A,B,C ELECTRONIC MODULATING CONTROL THERMOSTATS
Table 2. Option Settings
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T7984 Model |
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Parameter |
Selection |
A |
B |
C |
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Reheat Time |
Fast (7.5 min.); or Normal |
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Constant |
(15 min.) |
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Zero Energy |
3°F (1.5°C); or 5°F (3°C) |
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Band |
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Setpoint |
Heating; Cooling or H/C |
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Definition |
midpoint |
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Night |
5°F (3°C) heat/cool offset, or |
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Setback |
10°F (5°C) setback / cooling |
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shutdown |
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Main Sensor |
Remote or internal |
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Fig. 1. Dimensions in inches (mm)
Install the thermostat about 5 ft. (1.5 m) above the floor in an area with good air circulation at average temperature conditions.
Do not install thermostat where it may be affected by:
•drafts, or dead air spots behind doors and in corners.
•hot or cold air from ducts.
•radiant heat from sun or appliances.
•concealed pipes and chimneys.
•unheated (cooled) areas such as an outside wall behind the thermostat.
Mounting
The thermostat can be mounted directly on the wall with or without a wallplate or a standard single gang electrical box, or double gang with adaptor plate (accessory part 272846).
CAUTION
Disconnect power supply to prevent electrical shock or equipment damage.
Wiring
Typical wiring connections are shown in Fig.2 to Fig.7. Wiring connections may be made to the screw terminal block with 2- 18AWG or 1-14AWG, solid or stranded copper wires. Connect the system wires to the thermostat terminals. Push excess wire back into hole. Plug hole to prevent drafts.
Auxiliary screw terminal strip may be used in a junction box when the application requires multiple wires to be brought down at the thermostat. This can make troubleshooting, startup and servicing easier.
DIP Switch Settings
T7984 thermostats must be configured for proper operation by setting DIP switches.
T7984B
Reheat output control action: 7.5 or 15 minutes.
T7984B,C
Zero energy band (ZEB): 3°F (2°C) or 5°F (3°C)
Setpoint adjustment: cooling,centred, heating centred with limit override for commissioning.
Night setback amount: see Table 2 for complete listing of option settings.
T7984A,B,C
Main sensor, internal or remote.
Table 3. T7984 DIP Switch Definition
OUTPUT 2 ON/OFF CPH |
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T7984B only |
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For more information, see on/off output cycle per hour application note. |
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CYCLES/HOUR |
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S1 |
It is possible to fix the number of times per hour the on/off |
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FAST |
8 CPH |
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output will be energized. |
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SLOW 4 CPH |
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0 |
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T7984B & C only |
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ZERO ENERGY BAND |
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On models which have 2 outputs, 1 for cooling and 1 for |
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ZEB |
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S2 |
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5°F (3°C) |
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1 |
heating, it is possible to adjust the zero energy band value |
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3°F |
(1.5°C) |
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(dead band between heating and cooling endpoints). |
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T7984B & C only |
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SETPOINT DIAL DEFINITION |
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For more information, see setpoint dial definition & setpoint limitation application note. |
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DEFINITION |
S3 |
S4 |
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Models with cooling and heating outputs |
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75°F OVERRIDE |
1 |
1 |
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» Setpoint dial centered, 75˚F limitation not active. |
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HEATING DIAL |
0 |
1 |
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» Setpoint dial defined as heating, 75˚F limitation active. |
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COOLING DIAL |
1 |
0 |
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» Setpoint dial defined as cooling, 75˚F limitation active. |
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CENTERED HC |
0 |
0 |
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» Setpoint dial centered, 75˚F limitation active. |
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DAY/NIGHT SETBACK |
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T7984B & C only |
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HEAT SETBACK |
COOL SETUP |
S5 |
Night mode setpoints can be adjusted |
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to different values depending on the |
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10°F (5°C) |
20°F (10°C) |
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1 |
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application. |
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5°F (3°C) |
5°F (3°C) |
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0 |
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REMOTE SENSOR |
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T7984A, B & C |
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On model T7984A, switch S7 & S8 are not used. |
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MAIN SENSOR |
S6 |
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For duct return air or remote room sensor control only. |
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LOCAL INTERNAL |
1 |
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Do not use remote sensor in supply or discharge air |
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REMOTE SENSOR |
0 |
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control applications. |
ON = 1
OFF = 0 1 2 3 4 5 6
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95C-10815–2 |