Honeywell T451 Thermostat User Manual

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T451, T651  
Motor-Rated Precision Thermostats  
PRODUCT DATA  
FEATURES  
Deluxe styling for commercial buildings.  
Industrial grade MICRO SWITCH™ mechanism  
rated 1/2 hp inductive, 5 kW resistive.  
Vertical mounting on 2” x 4” NEMA-standard  
single-gang outlet box.  
High-sensitivity, vapor-filled stainless steel dual  
diaphragm sensing element.  
Engineering plastic base to isolate sensor from  
switch heat and minimize droop.  
CSA Certified, UL Listed.  
Altitude compensation.  
44°F (7°C) “frost protection” setting for heating  
application, independent of calibration or altitude.  
Color-coded leadwire connections.  
Range stops/locking cover security features for  
public areas.  
APPLICATION  
The T651 thermostat provides direct, accurate line voltage  
control of inductively-rated heating, ventilating, or cooling  
equipment used in commercial or industrial environments.  
The T451 provides precision line voltage control of motor-  
rated electric, gas or oil heating equipment.  
Contents  
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2  
Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2  
Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3  
Setting and Adjustment. . . . . . . . . . . . . . . . . . . . . . . . . . 4  
CL 4-01 • © Honeywell Limited/Limitée 2001  
95C-10903-1  
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T451, T651 MOTOR-RATED PRECISION THERMOSTATS  
SPECIFICATIONS • ORDER INFORMATION  
Finish: Classic beige-and-light gold standard.  
White models available.  
Important: The specifications given in this publication do  
not include normal manufacturing tolerances. Therefore this  
unit may not exactly match the listed specifications . This  
product is tested and calibrated under closely controlled  
conditions, and some minor differences in performance can  
be expected if these conditions are changed.  
Mounting:  
Mounts directly on vertical, single-gang NEMA Standard  
2” x 4”) electrical box.  
(
Wiring Connections:  
” (150 mm) leadwires suitable for connecting to aluminum  
Models:  
6
T451A SPST and T451B DPST (with positive off) for  
heating only.  
T651A SPDT for heating/cooling.  
conductors wiring if used with approved special service  
CO/ALR solderless wire connectors. Leadwires color-  
coded red for heating, blue for cooling, black for common.  
Control Range:  
Approvals:  
4
5
4 - 86°F (7 - 28°C) for models T451A, T651A.  
0 - 86°F (10 - 28°C) for model T451B.  
Canadian Standards Association Certified; File No. LR1322  
Performance Certified for electric heating per C273.4A.  
UL file E47434.  
Sensing Element: Vapor-filled dual diaphragm.  
Differential: 2°F (1°C)  
Accessories:  
272804A Range stops and cover locking assembly  
Droop: 2°F @ mid load range.  
(included in selected models only).  
Barometer Sensitivity: 1/8°F/”wc (0.3°C/kPa).  
Thermometer: 50 - 90°F (10 - 30°C) in 10°F (5°C) increments.  
Electrical Ratings:  
220213 Wallplate, covers old T451/T651 (1000 series)  
wall marks.  
TG511 Thermostat guard for security and protection.  
Fig. 1 — Dimensions of T451, T651 in inches (mm):  
50/60Hz  
120 V  
9.8A  
208V  
5.6A  
240V  
4.9A  
277V  
4.2A  
Full Load  
Locked Rotor  
Pilot Duty  
58.8A 33.6A 29.4A 25.2A  
125 VA  
Resistive  
22A Non Inductive  
2.5kW 4.5kW  
19ANI  
5kW  
Heating Only  
ORDERING INFORMATION  
When purchasing replacement and modernization products from your TRADELINE® wholesaler or your distributor, refer to the  
TRADELINE catalog or price sheets for complete ordering number, or specify:  
1
2
3
. Model  
. Electrical load(s)  
. Accessories.  
If you have additional questions, need further information, or would like to comment on our products or services, please write  
or phone:  
1
2
. Your local Honeywell Home and Building Control Sales Office (check white pages or phone directory).  
. Home and Building Control Customer Satisfaction  
Honeywell Inc., 1885 Douglas Drive North.  
Minneapolis, MN 55422 (612) 951-1000  
3. In Canada—Honeywell Limited, 35 Dynamic Drive, Toronto, ON M1V 4Z9, 1-800-405-9835.  
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.  
2
95C-10903-1  
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T451, T651 MOTOR-RATED PRECISION THERMOSTATS  
INSTALLATION  
WHEN INSTALLING THIS PRODUCT:  
Fig. 2 — Wiring connections  
1
. Read these instructions carefully. Failure to follow  
instructions can damage product or cause a hazardous  
condition.  
T451A (Heat only)  
T451B (Heat only with positive off)  
To  
Heating  
Load  
To  
2
3
4
. Check ratings given in instructions and on product to  
Heating  
Load  
make sure product is suitable for your application.  
. Make sure installer is a trained, experienced service  
technician.  
T651A (Heat only)  
T651A (Cool only application)  
. After completing installation, use these instructions to  
check out product operation.  
To  
Heating  
Load  
To  
Cooling  
Load  
!
WARNING  
This thermostat is a line voltage (120 to 277 Vac)  
control. Do not install it unless you are completely  
familiar and competent with home wiring.  
T651A (Heat–Cool application)  
To  
Heating  
Load  
If improperly handled there can be a risk of  
To  
Cooling  
Load  
240 volt electric shock hazard which may cause  
serious injury or death.  
1
2
3
4
Power supply; provide disconnect means and overload protection as required.  
Breaks on Positive Off.  
Exposed unused wires must be properly insulated.  
CAUTION  
. Disconnect power supply before making wiring  
connections to prevent electrical shock or equipment  
damage.  
!
1
Contact makes Black to Red on temperature fall;  
Black to Blue on temperature rise.  
4. Pre-bend and push leadwires into the electrical junction  
box.  
2
. All wiring must comply with national and local codes  
and ordinances.  
5
. Hold the thermostat base with one hand and remove the  
thermostat cover by grasping two sides of the cover and  
pulling outward.  
3
. When using aluminum conductors, all wiring connec-  
tions to this thermostat must be made to the factory  
installed leadwires using approved CO/ALR solderless  
connectors. A fire hazard may result otherwise.  
NOTE: If locking cover feature is desired, insert the locking  
cover clip in the thermostat base BEFORE mounting the  
thermostat on the wall (see Fig. 7).  
4
. To avoid handling the sensing element, do not remove  
thermostat cover until wiring is completed.  
6
. Using the screwdriver, secure the thermostat to the box by  
tightening the two mounting screws. Handle thermostat  
with care. Excessive pressure may damage the control  
knob or sensing element.  
5
. Thermostats are designed for use with appliances  
having a limit control.  
IMPORTANT: Before mounting the thermostat, turn the  
setting dial to the mid-position (indicator pointing to the  
top of the thermostat): this will prevent damage to the  
dial stop if the dial is accidentally turned by the screw  
driver when the top mounting screw is tightened. Do  
NOT press on diaphragm, diaphragm lever arm or  
setpoint knob to seat thermostat on the box: thermostat  
will be damaged.  
New Installations  
1. Install a single-gang electrical box oriented vertically about  
4’ to 5’ (1.5 m) above the floor on an inside wall or pillar  
where the thermostat will be subjected to typical room  
temperature.  
NOTE: To sense temperature properly, the thermostat  
must be placed away from concealed warm or cold water  
pipes, air ducts, or drafts from hallways, fireplaces or  
stairways. Do not place thermostat above convectors or  
in the flow from supply fans. Ideally, a thermostat should  
be close to the return air path to effectively measure  
average room temperature.  
Replacement Applications  
1
. Disconnect power supply before making wiring  
connections to prevent electrical shocks or equipment  
damage. All wiring must comply with applicable codes  
and standards.  
2. Wire installation in an approved fashion.  
2
. Remove the old thermostat from the wall, taking care not  
to damage the wiring insulation.  
NOTE: T651A and T451A do not feature a Positive Off  
setting, and may not be used as a disconnect switch.  
3
. Check the old insulation for cracks, nicks or fraying. Apply  
certified electrical tape where necessary to insulate wires,  
or replace the wires in an approved fashion.  
3
. Leave cover on the thermostat while making wiring  
connections. Use solderless connectors approved for the  
type, number and gauge of wires being joined.  
4
. Complete installation following steps 3 to 6 in the New  
Connect as per Fig. 2 for the appropriate application.  
Installations section.  
3
95C-10903-1  
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T451, T651 MOTOR-RATED PRECISION THERMOSTATS  
INSTALLATION  
4
. Install the cover. Wait five minutes to let the thermostat  
thermally stabilize and re-check calibration.  
Do not assume a thermostat is out of calibration until it has  
been installed and allowed to operate for several hours.  
Check Out  
Turn on power. Raise the temperature setting to energize  
the heating contact and break the cooling contact. The  
HVAC equipment should begin heating or stop cooling, as  
appropriate.  
Fig. 4 — Recalibrating  
Thermostat  
Fig. 5 — Installing  
Range Stops  
NOTE: For T451A and T651A models only, the thermostat  
will call for heat (disable cooling) when the setpoint dial  
is at full counter-clockwise position. This setting is the  
phase change point of the diaphragm’s vapor fill and is  
independent of calibration. To de-energize the load(s),  
turn off power at the circuit breaker panel, or add a  
separate disconnect switch.  
Altitude Compensation  
T451, T651 units are calibrated at the factory for accuracy  
at 500 feet above sea level. No recalibration is needed if the  
switch operates at the same temperature indicated on the  
thermometer.  
The vapor-filled diaphragm sensor is affected by barometric  
pressure and altitude. Deviations up to ± 1°F (1/2°C) are  
within normal operation. Control point drops 2°F every  
Insert pins into  
temperature stop  
positions  
1
000 ft. (1°C/300 m) above sea level. See Fig. 3 for  
Security Features:  
Range Stops  
recommended action.  
1. Set thermostat to desired setpoint. Remove cover.  
2
. Install plastic dowels supplied (or purchased separately)  
into minimum and/or maximum range stop holes on inside  
back of cover (Fig. 5).  
Fig. 3 — Altitude Correction  
Elevation  
Recommended  
Action  
3. Re-install cover. Check operation of range stops.  
(in feet)  
Typical City  
Fig. 6 — Cover Locking Kit  
0
to 2000  
Toronto, Ontario  
Phoenix, Arizona  
Leave as is  
2
000 to 4000  
000 to 6000  
Las Vegas, Nevada  
Calgary, Alberta  
Move clockwise  
2 to 3 marks  
4
Denver, Colorado  
Move clockwise  
4 to 5 marks  
Salt Lake City, Utah  
To Recalibrate  
1
2
3
. Remove cover. Set the tab on setpoint knob to the leftmost  
radial mark visible on top of the triangular arm that holds  
the dual diaphragm sensor (Fig. 4).  
Locking Cover  
1. Remove cover by pulling straight out.  
®
. Without rotating the knob, remove it from the thermostat  
by pulling straight out, while holding the base against  
the wall.  
2. Insert Tinnerman Speed Nut s into slots top and bottom of  
thermostat base.  
3 Drive Allen screw into Speed Nut until head is flush with  
outside edge of thermostat base.  
. Now, rotate the removed setpoint knob clockwise by the  
amount of temperature error. Each mark on the triangular  
arm represents 2°F (1°C) of adjustment. Snap the knob  
back onto the setpoint cam.  
4. Re-install cover. Lock by backing out Allen screw until  
screw body protrudes through cover hole. To unlock cover,  
drive Allen screw into thermostat base.  
Home and Building Control  
Home and Building Control  
Honeywell Limited-Limitée  
35 Dynamic Drive  
Honeywell Inc.  
1985 Douglas Drive North  
Golden Valley, MN 55422  
Toronto, ON M1V 4Z9  
4
95C-10903-1  

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