T6984F,G Electronic Floating Control Thermostats FEATURES PRODUCT DATA P+I control action provides accurate, stable room temperature control. Used with ML644 Series 60 Direct Coupled Damper Actuators. User-friendly set point knob. Output status LED for installer check-out. Can drive up to four (4) ML644 Actuators. Fixed actuator timing at 8.4 minutes. APPLICATION These microprocessor-based thermostats provide proportional-plus-integral individual room control in underfloor air delivery systems. They are used with the Honeywell ML644A Actuator. Contents Application... Features... Specifications... Ordering Information... Installation... 3 Operation... 4 Checkout... 7 U.S. Registered Trademark Copyright 00 Honeywell All Rights Reserved 63-585-
SPECIFICATIONS 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: See Table. Dimensions: See Fig.. Table. T6984 Models. Main Temperature Output Sensor Output Output Model 3 T6984F floating internal Night Setback floating internal on/off on/off dry contact Accuracy: F (0.4 C). Precision: ±0.5 F (0.4 C). Approvals: Designed for Class II low voltage installation only. Case and cover meet UL94-5V flammability requirements, and North American codes for line voltage thermostat enclosures. Meets requirements of F.C.C. Part 5 Class B, IEC 80-3 for radio frequency interference. CE. Accessories: 7846 Adapter Plate for British standard, European, doublegang NEMA electrical boxes, or for surface mounting. -9/6 (39) BUTTON SWITCH Mounting: Mounts to single-gang NEMA-standard in. x 4 in. electrical box, or directly to wall. Requires -/8 in. (35 mm) access hole for wiring. 3-3/6 (8) 3/6 (5) -9/6 (39) 3/6 (5) Wiring: Four (T6984F) and eight () /8 in. screw terminals suitable for no.8 AWG ( mm ) wires each. Power Supply: 9-30 Vac, 50/60 Hz, VA, Class. (Does not include actuator power requirements.) SYSTEM Operating Ambient: 3-04 F (0-40 C) at 5-95% RH (non-condensing). 4-3/4 (0) Setpoint Range: Scale marked with +/- scale only, for warmer/cooler indication. With no range stops installed 55-90 F (3-3 C). With factory installed range stops 65-80 F (8-7 C). 3-3/6 (8) Switched Output Rating: Output floating: 4 Vac,.0A maximum running,.a inrush. The thermostat can directly drive up to four ML644A Actuators maximum. Outputs and 3 reheat ( only): 4 Vac 0.5A maximum running,. A inrush. Outputs are protected with self-resetting circuit interrupter. M006 Fig.. Dimensions in in. (mm). /6 (7) 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:. Your local Home and Building Control Sales Office (check white pages of your phone directory).. Home and Building Control Customer Relations Honeywell, 885 Douglas Drive North Minneapolis, Minnesota 554-4386 In Canada Honeywell Limited/Honeywell Limitée, 35 Dynamic Drive, Scarborough, Ontario MV 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. 63-585
INSTALLATION Location Install the thermostat about 4 ft. (.m) above the floor in an area with good air circulation at average temperature conditions. Do not install thermostat where it can 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. 3 4 4 5 4 3 OPEN POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. M644 A MAXIMUM OF FOUR ML644 ACTUATORS CAN BE CONNECTED TO ONE CONTROLLER (WHEN CONNECTED EITHER DIRECTLY OR THROUGH A 3003967-00 POWER CONTROL MODULE). OUTPUT. OUTPUT 4 VAC RELAY OR VALVE. CLOSE 4 VAC OPEN CLOSE COMMON L L (HOT) 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 7846 Adapter Plate. CAUTION Electrical Shock or Equipment Damage Hazard. Can shock individuals or short equipment circuitry. Disconnect power supply before installation. 5 NSB CONTACT FROM A CENTRAL TIMER. Fig. 3. Typical wiring. 4 VAC 4 VAC M003 L L Wiring 4 VAC CAUTION Equipment Damage Hazard. Ground loops can short equipment circuitry. Avoid grounding all transformer secondaries (low voltage sides). Typical wiring connections are shown in Fig. through 5. Wiring connections can be made to the screw terminal block with -8AWG or -4AWG, solid or stranded copper wires. Connect the system wires to the thermostat terminals. Push excess wire back into hole. Plug hole to prevent drafts. T6984F OPEN CLOSE 4 VAC M644 OPEN CLOSE COMMON POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. A MAXIMUM OF FOUR ML644 ACTUATORS CAN BE CONNECTED TO ONE T6984F CONTROLLER (WHEN CONNECTED EITHER DIRECTLY OR THROUGH A 3003967-00 POWER CONTROL MODULE). M0034 Fig.. T6984F wiring. L (HOT) L POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. NSB CONTACT FROM A CENTRAL TIMER. M0048 Fig. 4. Wiring multiple Thermostats with a single transformer. 4 VAC 4 VAC 4 VAC POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. NSB CONTACT FROM A CENTRAL TIMER. L L M0049 Fig. 5. Wiring multiple Thermostats with individual transformers. L L L L 3 63-585
OPERATION NOTE: The output electronic contacts (triacs) are protected with a self-resetting circuit interrupter. In the event of an overload or short circuit, the self-resetting interrupter reduces the load to a very low level. If power is removed or the overload or short circuit disappears, then the circuit interrupter returns to its normal condition and allows normal operation. Output Proportional Tri-state Floating The main thermostat output is a P+I modulating floating type signal that uses a set of two, 4 Vac non-isolated electronic contacts to control the floating damper actuator(s). One contact to open the end device, the other to close the end device. The actuator will open and close to multiple positions according to demand. When demand and temperature are satisfied, the thermostat stops moving the actuator, leaving it at its last position until the demand changes (see Fig. 6). The internal green LED indicates that the actuator is opening or opened. The internal yellow LED indicates the actuator is closing or closed. See Table 6. On power-up, the close output is energized for 8.4 minutes to synchronize all actuators. After this, normal control operation resumes. Every.5 hours, the synchronization process is repeated. 00% OPEN) 50% 0% CLOSED) COOLING ONLY MODE TEMPERATURE RISE OUTPUT (FLOATING) Fig. 6. T6984F sequence. DIAL CENTERED HEATING ONLY MODE M005 Temperature Differential ( only) The T6894G thermostat has two distinct setpoints, one for heating, the other for cooling (see Fig. 3). When the room temperature is between these setpoints, neither heating nor cooling are working and the room temperature is in the Differential. When room temperature drops below the heating setpoint, Output energizes. When room temperature rises above the cooling setpoint, Output energizes. Output and 3 On/Off ( only) 4 Vac on/off outputs which are normally used to control reheat in a zoned system. Example: electric baseboard or duct heater relay, on/off 4 Vac hydronic valve, etc. Three different control sequences are offered: Binary (see Fig. 7 and Table ). Fan and one heating step (see Fig. 8): Fan runs whenever there is heating demand. Two heating steps (see Fig. 9): Use the fan as heating stage and cycle it more often. This sequence is used when return plenum air is hot enough to be used as a primary heating stage. NOTE: All control sequences use Output for floating control of cooling. The internally-mounted status LED indicates the output action. The red LED indicates that the output electronic contact (triac) is energized. Table. Binary Control Sequence. Output Output 3 Start a On Off Fan b Off On Stage heat (fan on) c On On Stage heat (fan and stage heat on) a The stages/fan turn off in the reverse order that they turn on (see Fig. 7). b The Fan must be on in order for Stage to turn on. c Stage heat must be on for Stage to turn on. Cycles Per Hour (CPH) It is possible to fix the number of times per hour the reheat end device energizes. Those settings are adjusted with a dip switch (S). Two different settings are possible: 4 CPH and 8 CPH. However, the CPH switch (S) modifies only certain outputs depending on the sequence selected (see Table 3). Table 3. Cycles Per Hour. Output Output 3 Binary sequence No No Fan and heating No (Fan output) Yes (S applies) step sequence heating step sequence Yes (S applies) Yes (S applies) Two values are available for the Differential: F ( C) and 5 F (3 C). The value can be adjusted with the dip switch (S). 63-585 4
3 OFF OFF TEMPERATURE 3 ON OFF OUTPUTS AND 3 TRUE HEATING ON ON DIFFERENTIAL TEMPERATURE RISE DIAL CENTERED IN DIFFERENTIAL. TRUE COOLING OUTPUT (FLOATING) Fig. 7. binary heat control sequence (Output and 3 binary heating mode). 00% OPEN) 50% 0% CLOSED) M007 ON OFF OUTPUT ON TRUE HEATING OUTPUT OUTPUT OFF DIFFERENTIAL TEMPERATURE RISE TRUE COOLING OUTPUT (FLOATING) 00% OPEN) 50% 0% CLOSED) ON TRUE HEATING TRUE COOLING 00% OPEN) DIAL CENTERED IN DIFFERENTIAL. SELECTABLE CYCLES PER HOUR (CPH): 4 OR 8. M009 Fig. 9. heat control sequence 3: heating steps (Outputs and 3 time proportioning heat). OFF 50% FAN ON FAN (OUTPUT ) FAN OFF DIFFERENTIAL TEMPERATURE RISE OUTPUT (FLOATING) 0% CLOSED) DIAL CENTERED IN DIFFERENTIAL. SELECTABLE CYCLES PER HOUR (CPH): 4 OR 8. M008 Fig. 8. heat control sequence : Fan, stage heat (Output on/off fan; Output 3 time proportioning heat). 5 63-585
Night Setback Day/Night Modes ( only) An energy saving mode by which the actual setpoints are modified to different values than the ones adjusted on the dial. The cooling setpoint increases, the heating setpoint decreases. This mode is energized with a dry contact from a remote time clock. Two different setup and setback values are adjustable with a DIP switch (see Fig. 0 and Table 4). SWITCH 3 4 5 ON = OFF = 0 M003 Fig. 0. DIP switch definitions. Table 4. DIP Switch Settings. Switch Switch Switch 5 Switch Binary Day/Night Setback Position Cycling Differential Heating Cooling 0 4 CPH F ( C) 5 F (3 C) 5 F (3 C) 8 CPH 5 F (3 C) 0 F (6 C) 0 F ( C) Switch 3 Switch 4 Reheat Sequence 0 0 Binary Fan and Heating Step 0 Heating Steps NOTES: The system LED on this thermostat cover flashes to indicate that it is in night mode. Override night setback temporarily (-/ hours) by depressing the override button (on the cover). Press the button again to fully restore thermostat setpoints to day mode. One night setback timer contact can be used for multiple thermostats. 63-585 6
CHECKOUT Service LED All thermostats have internal service LED lights and a system status LED on the cover. The internal service LED are colored lights that can be viewed from the thermostat side when they are energized. The system status LED is mounted on the cover. (See the checkout and start up procedures section in the Application Manual.) Thermostat operation can be confirmed with the thermostat cover system and service status LED (see Table 5). Table 5. System Status LED. Model Color Explanation T6984F Green High Intensity = Demand for cooling. Low = no demand Red Flashing = night setback and setup activated Table 6. Internal Service LED. F G Color Indication X X Green Actuator/valve opening X X Yellow Actuator/valve closing X Red On/Off output is closed. Load energized. X Red 3 On/Off output 3 is closed. Load energized. Test Condition ( only) Table 7. Test Condition. Rotate Knob to Green Yellow Red Reheat Red 3 Reheat Minimum Position (-) On Off Off Off Maximum Position (+) Off On On On Power-up Sequence When power is first applied to the thermostat, a 4V pulse equal to the actuator travel time is applied to the actuator to bring it to the fully closed position. This synchronizing sequence is required as the thermostat has no way of knowing the actuator position. Once the actuator is closed, the pulses to the actuator are synchronized with the actuator position. The thermostat then positions the actuator exactly, using timed voltage pulses. IMPORTANT The thermostat will not respond to setpoint demands until this reset sequence is complete. NOTES: On power-up, the close output is energized for 8.4 minutes to synchronize all actuators, then normal control operation resumes. If the box reaches fully open or closed position (based on timing), actuators are de-energized. Every.5 hours, a synchronization process (by closing the box) is repeated. 7 63-585
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