Honeywell T7984 C User's Manual
Contents
1. Duct Output 2 24 Vac on off or On off relay or valve 2 10 Vdc valve or VAV l Room Output 1 analog actuator T T 2 10 Vdc a i I ro gt Remote Mode input Input 2 10 Vdc R P aee sensor input 24 Vac i J i Common EEE 0 Vac 24 Vac NSE contact Power supply gt from a central timer NSB input 0Vac 1 24 Vac Transformer Fig 5 T7984B Wiring Mode A jumper not installed Mode B jumper installed Output 1 analog in cooling mode Output 1 analog in heating mode i i Output 2 on off i li d Output 2 on off in heating mode SETPOINT DIAL DEFINITION utput 2 on off in cooling mode SETPOINT DIAL DEFINITION HEATING COOLING Ena HEATING Serene COOLING End SETPOINT SEIROINT SETPOINT Device SETPOINT are SETPOINT Device CENTERED End a opened IN ZERO End 100 ps NEST BAND a pene 100 10 Vdc ENERGY BAND cae 7 10Vde 50 ra 50 F Device A Device d closed Device Device closed _ f 2 Vdc off 0 om 2Vdc 0 i OUTPUT 1 OUTPUT 2 OUTPUT 2 NOE oumu 1 ANALOG ONIOFE ZERO ENERGY BAND Temperature increase Fig 6 T7984B Sequence Mode A DIP SWITCH SETTINGS SETPOINT DIAL DEFINITION 1 1 OUTPUT 2 ON OFF CPH ZERO ENERGY BAND 5 F 3 5 o 3 F_ 1 5 C ZERO ENERGY BAND Temperature increase Fig 7 T7984B Sequence Mode B DAY NIGHT SETBACK HEAT SETBACK COOL SE2. Setpoint dial centered 75 F limitation not active o 1 gt Setpoint dial defined as heating 75 F limitation active o Setpoint dial defined as cooling 75 F limitation active CENTEREDHC 0 0 gt Setpoint dial centered 75 F limitation active DAY NIGHT SETBACK HEAT SETBACK COOL SETUP Night mode setpoints can be adjusted 10 F 5 C 20 F 10 C 1 to different values depending on the oF BO oF GO 0 application T7984B amp C only REMOTE SENSOR 17984A B amp C On model 179844 switch 57 amp S8 are not used MAIN SENSOR For duct return air or remote room sensor control only LOCALINTERNAL 1 Do not use remote sensor in supply or discharge air REMOTE SENSOR 0 control applications 95C 10815 2 T7984 A B C ELECTRONIC MODULATING CONTROL THERMOSTATS T7984A Output 1 analog Changeover input Remote sensor 2 10V for Out 1 option Cooling and or X X heating WIRING To install a remote duct or room temperature sensor adust DIP the screw terminals and wire as shown switch S6 to 0 off and wire as shown To reverse operation of output 1 to heating install the If sensor is used wire 1changeover sensor per thermostat changeover contact or the changeover sensor across Duct or Room SEQUENCE Remote sensor input E _ 0 Vac y Not used Output 1 2 10 Vdc Cha
3. 2 to 10 Vdc 2 mA max SWITCHED OUTPUT RATING 0 5A running 1 1A inrush 24Vac protected with selfresetting fuse OPERATING PARAMETERS See Table 2 for installer selections APPROVALS Designed for Class II low voltage installation only Case and cover meets ULE94 5V flammability requirements and North American codes for line voltage thermostat enclosures Meets requirements of F C C Part 15 Class B IEC 801 3 for radio frequency interference ACCESSORIES 272845 Remote sensor wall mounted 272846 Adaptor plate for 2 gang NEMA or British 75 mm electrical box 272847 Remote sensor duct mounted 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 Limit e 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
4. 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 179848 only For more information see on off output cycle per hour application note CYCLES HOUR It is possible to fix the number of times per hour the on off FAST__8CPH output will be energized SLOW__4CPH 0 ZERO ENERGY BAND 17984B amp C only On models which have 2 outputs 1 for cooling and 1 for heating it is possible to adjust the zero energy band value dead band between heating and cooling endpoints SETPOINT DIAL DEFINITION 17984B amp C only For more information see setpoint dial definition amp setpoint limitation application note DEFINITION Models with cooling and heating outputs 1 1_
5. 10815 2 2 T7984 A B C ELECTRONIC MODULATING CONTROL THERMOSTATS Table 2 Option Settings T7984 Model Parameter Selection A B Cc Reheat Time Fast 7 5 min or Normal Constant 15 min Zero Energy 3 F 1 5 C or 5 F 3 C Band Setpoint Heating Cooling or H C Definition midpoint Night 5 F 3 C heat cool offset or Setback 10 F 5 C setback cooling shutdown Main Sensor Remote or internal e e Fig 1 Dimensions in inches mm INSTALLATION Location nstall 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
6. Supply 78 F Temp Fig 12 Changeover temperature trip point Main Temperature Remote Sensor 179844 B C All thermostats have their internal sensing device Thermistor mounted internally in the thermostat On the T7984A B amp C models it is possible to install a remote room or remote duct return sensor at a different location than the thermostat See wiring diagram for each model on how to wire the sensor The remote sensor are not to be used for supply control applications Zero Energy Band T7984B amp C Thermostats which have cooling and heating outputs T7984B amp C have 2 distinct setpoints one for heating the other for cooling see the control curves section for each model When the room temperature is between these to setpoints both heating and cooling outputs are off and the room temperature is in the Zero Energy Band When the room temperature drops below the heating setpoint output 2 output will energize When the room temperature rises above the cooling setpoint output 1 will energize Two settings values are available for Zero Energy Band 3 F 1 5 C or 5 F 3 C can be adjusted with dip switch S2 Setpoint Dial Definition T7984 B amp C Because these thermostats have 2 distinct setpoints one for heating the other for cooling the thermostat setpoint dial knob need to be defined as being either e The true heating setpoint The true cooling setpoint e Or centered in the middle of the
7. the one mounted on the cover See the checkout amp start up procedures section Table 6 System Status LEDs Thermostat operation can be confirmed with the System status LED on the thermostat cover Model Color Explanation T7984A green High intensity Demand for cooling or heat Low no demand T7984B C red Flashing Night setback set up activated Table 7 Internal Service LEDs A B C Color Indication when e green Intensity is proportional to output 1 red On off output 2 is closed load energized e red Intensity is proportional to reheat output Test Condition 1 No contact changeover input and changeover sensor disconnected No wire on mode input 2 T7984B amp C set DIP switch S3 and S4 to ON position to remove 75 F 24 C limitation 3 Room termperatures must be between 60 80 F Table 8 Knob position Red reheat models only Rotate Knob to Green T7984B amp C Minimum Position ON OFF Maximum Position OFF ON The night setback feature can be temporarily overridden for 2 1 2 hours by depressing the override button on the thermostat cover Honeywell Limited Honeywell Limit e Scarborough Ontario M1V 429 Honeywell Printed in U S A on recycled 2005 Honeywell International Inc amp paper containing at least 10 95C 10815 2 M S Rev 09 05 post consumer paper
8. 4 cycles per hour 8 cycles per hour Anything using a gas fired or N C 24 Vac thermal valve oil fired terminal reheat device Hot wax thermal body valve Any gear driven end device valve or damper actuator Properly sized electric base Oversized capacity electric board strip base board strip Properly sized electric duct Oversized capacity electric heater duct heater Output 2 Modulating Analog Output 2 to 10Vdc T7984C only A modulating signal that uses a variable Vdc signal for the control of analog valve actuator or SCR power controller which is normally used to control terminal reheat in a zone system This type of output on the T7984C uses a half wave rectifier bridge If the same transformer is to be used for the thermostat and the end device be sure to select end devices which also use a half wave rectifier bridge There is a status LED mounted internally that indicates the action of the output The red LED intensity is proportional to the action of the output Automation and Control Solutions Honeywell International Inc 1985 Douglas Drive North Golden Valley MN 55422 customer honeywell com 35 Dynamic Drive U S Registered Trademark CHECKOUT Service LED All thermostats have internal service LED amp a system status Led on the cover The internal service LED are colored lights that can be viewed from the side of the thermostat they are energized and the system status LED is
9. Changeover Temperature Mode Selection Model Output 1 For Output 1 Output 2 Night Setback Sensor Input T7984A Modulating 2 to Dry Contact or On off Internal or 10 Vde Sensor remote T7984B Modulating 2 to Dry Contact Internal or Jumper 10 Vde remote T7984C Modulating 2 to Dry Contact or Modulating 2 to Dry Contact Internal or 10 Vde Sensor 10 Vde remote Remote sensor models are 272845 Remote wall mount sensor 272847 Remote duct mount sensor DIMENSIONS See Figure 1 MOUNTING Mounts to single gang NEMA standard 2 x 4 electrical box or directly to wall requires 1 1 8 35Emm access hole for wiring WIRING Four to eight 1 8 screw terminals suitable for 2 no 18 AWG 1 mm 2 wires each depending on model POWER SUPPLY 19 30 Vac 50 60 Hz 2 VA Class 2 Does not include actuator or reheat stage power requirements OPERATING AMBIENT 32 104 F 0 40 C at 5 95 Relative Humidity non condensing ACCURACY 1 F 0 6 C PRECISION 1 F 0 5 C tempera ture after stabilization PRECISION 1 F 0 5 C temperature after stabilization SETPOINT RANGE 55 90 F 13 32 C T7984A Heating 55 75 F 13 24 C T7984B C Cooling 75 90 F 24 32 C T7984B C ORDERING INFORMATION The maximum heating setpoint and minimum cooling setpoint is electronically limited to 75 F 24 C REMOTE SENSOR 47 kQ NTC thermistor part nos 272845 and 272847 ANALOG OUTPUT
10. ETPOINT SETPOINT DIAL DEFINITION HEATING COOLING HEATING SETPOINT COOLING SETPOINT CENTERED SETPOINT End SETPOINT CENTERED SETPOINT End IN ZERO beva End End IN ZERO 100 Device ENERGY BAND enera q 100 Davice ice ENERGY BAND opened 10 Vde opened 10 Vde 10 Vdc x l x I 50 50 Be l l End End l Frid k End l Device Device Device a Device l closed closed eiosed closed 0 2 Vdc 2 Vdc 2Vde 2 Vdc t H 0 f OUTPUT 2 OUTPUT 1 poe 2 OuTPUT 4 ANALOG ANALOG ANALOG ZERO ENERGY BAND ZERO ENERGY BAND Temperature increase a Temperature increase gt gt Fig 10 T7984C Sequence DAY NIGHT SETBACK TE MSG HEAT SETBACK COOL SETUP 10 F 6 C 20 F 00 C 5SFeO 0 REMOTE SENSOR MAIN SENSOR LOCAL INTERNAL REMOTE SENSOR _ 0 Fig 11 T7984C Dip Switch Setting 95C 10815 2 6 T7984 A B C ELECTRONIC MODULATING CONTROL THERMOSTATS Output 1 Modulating Analog Output 2 to 10Vdc T7984 All Main output of the thermostat On the T7984 series that output is modulating PI analog 2 to 10 Vdc That signal uses a variable Vdc signal for the control of analog damper actuator and analog valve actuator This type of output on the T7984 series uses a half wave rectifier bridge There is a status LED mounted internally that indicates the action of the output The green LED intensity is prop
11. Honeywell T7984 A B C Electronic Modulating Control Thermostats Honeywell 85 Honeywell 80 ub 80 gt 65 V 755 AN ny 85 3 APPLICATION These microprocessor based thermostats provide proportional integral Pl 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 PRODUCT DATA FEATURES PI proportional and integral control action provides accurate stable room temperature control e 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 e All models feature output status LEDs for installer check out e Locking cover and range stops are standard e Night setback models feature selection of two different offset temperatures and use central time switch control e Night setback models feature 2 1 2 hour local timed override e 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 requireme
12. TUP 10 5 20F 100 1 5 F BO SFG o REMOTE SENSOR MAIN SENSOR LOCAL INTERNAL REMOTE SENSOR _ 0 Fig 8 T7984B Dip Switch Settings 5 95C 10815 2 T7984 A B C ELECTRONIC MODULATING CONTROL THERMOSTATS T7984C Output 1 analog Output 2 Changeover input Day Night Remote sensor 75 F setpoint 2 10V analog 2 10V for Out 1 mode NSB option limit Cooling and Heating only X X X X Heating WIRING To install a remote duct or room temperature sensor adust DIP switch S6 to 0 off and wire as shown To reverse operation of output 1 to heating install the changeover contact or the changeover sensor across the screw terminals and wire as shown If sensor is used wire 1changeover sensor per thermostat Changeover contact Changeover sensor Duct Output 2 or 2 10 Vdc Room Output 1 i 2 10 Vdc 2 10 Vdc valve or VAV l KAN Remot Wee Changeover input for Out 1 ji l 1 l KS sensor input i 1 i C 0 Vac 24 Vac analog actuator T be Input 2 10 Vdc Input 2 10 Vdc 24 Vac 24 Vac Common Common NSB contact Power suppl from a central timer pp 0 Vac NSB input ae 24 Vac Transformer Fig 9 T7984C Wiring SEQUENCE SETPOINT DIAL DEFINITION S
13. Zero Energy Band This can be adjusted with dip switch S3 amp S4 See the control curves section for each model 75 F 25 C Setpoint Limitation T7984B amp C Models with a reheat output have setpoint limitation capability compatible with ASHRAE 90 1 Both heating and cooling setpoints are internally limited to 75 F 24 C The cooling setpoint cannot go below 75 F while the heating setpoint cannot go above 75 F This setpoint limit can be overridden for system checkout by setting the DIP switches S3 1 and S4 1 NSB Day Night Mode T7984B amp C An energy saving mode by which the actual setpoints are modified to different value than the ones adjusted on the dial The cooling setpoint will go up and the heating setpoint will go down This mode is energized with a dry contact from a remote time clock Table 4 DIP switch setup and setback values Two different setup amp setback value can be adjusted with a DIP switch S5 1 10 F 6 C heating 20 F 12 C cooling setpoint setpoint setback setup equivalent to cooling shut down S5 0 5 F 3 C heating 5 F 3 C cooling setpoint setpoint setback setup The system LED on the thermostat cover on these models will flash to indicate that the thermostat is in night mode The night mode can be overridden for 2 5 hours for each thermostat individually by pressing the button switch on the thermostat cover This will bring back the thermostat t
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15. ngeover input for Out 1 24 Vac Power supply j 0 Vac Changeover op Changeover contact sensor 2 10 Vdc valve or VAV analog actuator j Input 2 10 Vdc _ 24 Vac Common 24 Vac Transformer Fig 2 T7984A Wiring gt SETPOINT DIAL CENTERED Heating mode End End T We changeover Device y Device input active opened opened 10Vde gt s 10 Vdc 50 Closed End End 0 Device y Device closed closed gt OUTPUT 1 ANALOG Temperature increase DIP SWITCH SETTINGS 95C 10815 2 Fig 3 T7984A Sequence lt lt Not used ON 1 alala OFF 0 16 7 8 REMOTE SENSOR MAIN SENSOR LOCAL INTERNAL REMOTE SENSOR Fig 4 T7984A Dip Switch Settings 4 Cooling mode T7984B T7984 A B C ELECTRONIC MODULATING CONTROL THERMOSTATS Output 1 analog Output 2 Mode input Day Night Remote sensor 75 F setpoint 2 10V on off jumper mode NSB option limit Cooling Heating Mode A Jumper out X X X Heating Cooling Mode B Jumper in WIRING To install a remote duct or room temperature sensor adjust DIP switch S6 to 0 off and wire as shown To enable mode B of operation install a jumper across the screw terminals and wire as shown
16. nts of ASHRAE 90 1 e Heat cool models have installer definable setpoint at midpoint of Z E B at heating setpoint or at cooling setpoint e Reheat models feature fast slow response selection to match heating system dynamics e DIP switch selectable 75 F 24 C high limit heating setpoint and low limit cooling setpoint Horizontal and vertical covers included Contents ADPIICAT ON isinan eaaa aE eet get 1 PO AtUIES sstcncessiectnszsceckstestansas tesiaasenactestesetasertaedsiectitasts ake 1 SPECI CATIONS ai i552 cece sceticdeaatae sede chaste stan eda eaae EEEE 2 Ordering Information cccccceeeseeeeeeseeeeceeeeeeeeeaeeeeeeees 2 IAS CAM ATOM cssdsnecees sli codcndcs fesvectites cnahssndcebedeeseled onde cedetdeubentbaes 3 TL OBSA AE E O ATT 4 T7994 B en eee nen eer n aaa RE EEEn E Eai 5 TP 9B 4G E E Pespercceeennpeeep steduets ahaeie 6 CHECKOUT de ae ea cece R tues 8 95C 10815 2 T7984 A B C ELECTRONIC MODULATING CONTROL THERMOSTATS 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 T7984A B C 2 to 10 Vdc analog output Table 1 Model Specifications Cool Heat Main
17. o the day mode setpoints A common NSB timer contact may be used for multiple thermostats 95C 10815 2 T7984 A B C ELECTRONIC MODULATING CONTROL THERMOSTATS Output 2 On Off T7984B only A 24 Vac on off output which is normally used to control terminal reheat in a zoned system Example electric base board relay electric duct heater relay perimeter on off 24 Vac valve etc This output can also be used for cooling applications with the mode jumper installed See the control curves for T7984B There is a status LED mounted internally that indicates the action of the output The red LED indicates that the output electronic contact triac is energized This electronic contact triac is rated at 1 1A max in rush and 0 5A running This electronic contact triac is protected with a PTC self resetting fuse In the event of an overload or a short circuit the PTC self resetting fuse will reduce the load to a very low level If the power is removed or the overload or the short disappears the PTC fuse will return to its normal state and allow normal operation CPH Cycles per Hour It is possible to fix the number of time per hour the reheat end device will be energized Those settings are adjusted with DIP switch S1 Two different settings are possible 4 cycles per hour or 8 cycles per hour Use the following setting for the following reheat device applications Table 5 Cycle settings for reheat device applications
18. ortional to the action of the output Mode Input T7984B only Model T7984B has a mode input This thermostat is designed to operate and function in 2 distinct mode of operation depending on the application requirements This input is not a changeover input for output 1 Installing a jumper on the mode input will reverse modulating output 1 to operate as a heating only output amp the on off output 2 as a cooling only output See the control sequence section for each thermostat Heat Cool Changover of Output 1 T7984A amp C Models T7984A amp C all have the possibility of changeover for output 1 Automatic changeover is used on systems were a valve or a VAV unit may have cold and hot water or air in the same system depending on the season Basically output 1 is primarily cooling Direct Acting when the changeover input is not activated Activating the changeover input reverses the function of output 1 to heating mode Reverse Acting so that the thermostat can use the end device as a heating device instead of a cooling device A common contact may be used for multiple thermostats For the T7984 series a single common dry contact or 1 supply sensor per thermostat can be used for changeover A common contact may be used for multiple thermostats If a supply sensor is used changeover temperature trip point from cooling to heating is as follows Output 1 Heating mode Output 1 Cooling mode 25 C 26 C M24003 75 F
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