Honeywell t8501A, t8501B, t8501C, t8501D Installation Instructions Manual
T8501A,B,C,D
Microelectronic Thermostats
INSTALLATION INSTRUCTIONS
APPLICATION
The T8501 Microelectronic Thermostat provides electronic control of 24 Vac single-stage heating and cooling systems.
Refer to Table 1 for a general description of the thermostat. All T8501 Thermostats require a common wire to supply
power.
Table 1. Description of T8501 Thermostats.
T8501 System Changeover
A Heat only None None None —
B Heat only None Heat-Off On-Auto Select models have only a system switch or fan
C Heat-Cool Manual Heat-Off-Cool On-Auto System and fan selections are done by
D Heat-Cool Automatic Heat-Off-Cool-Auto On-Auto System and fan selections are done by
System
Selection
Fan
Selection Comments
switch and some models have both.
switches.
keyboard.
RECYCLING NOTICE
If this control is replacing a control that contains
mercury in a sealed tube, do
control in the trash.
Contact your local waste management authority for
instructions regarding recycling and the proper
disposal of the old thermostat.
not
place your old
INSTALLATION
When Installing this Product...
1. Read these instructions carefully. Failure to follow
the instructions can 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 completing installation, use these instructions
to check out the product operation.
Copyright © 1996 Honeywell Inc. • • All Rights Reserved
CAUTION
Disconnect power supply to prevent electrical
shock or equipment damage.
Location
Install the thermostat about 5 ft (1.5m) above the floor in
an area with good air circulation at average temperature.
See Fig. 1.
Do not install the thermostat where it can be affected by:
—drafts, or dead spots behind doors and in corners.
— hot or cold air from ducts.
—radiant heat from sun or appliances.
— concealed pipes and chimneys.
— unheated (uncooled) areas such as an outside wall
behind the thermostat.
Wallplate Installation
The thermostat can be mounted horizontally on the wall or
on a 2 in. x 4 in. wiring box. Position wallplate horizontally
on the wall or on a 2 in. x 4 in. wiring box.
쐃 Position and level the wallplate (for appearance
only). The thermostat will function properly even
when not level.
X-XX UL
69-0959
T8501A,B,C,D MICROELECTRONIC THERMOSTATS
WALL
ANCHORS
(2)
NO
WIRES
THROUGH WALL
YES
NO
5 FEET
[1.5 METERS]
Fig. 1. Typical location of thermostat.
WALL
쐏 Position the wallplate over the holes, pulling wires
through the wiring opening.
쐄 Loosely insert the mounting screws into the holes.
쐂 Tighten mounting screws.
WIRING
All wiring must comply with local electrical codes and
ordinances. Refer to Fig. 3 through 5 for typical hookups.
A letter code is located near each terminal for identification.
NO
M10106
MOUNTING
HOLES
MOUNTING
SCREWS
Fig. 2. Mounting the wallplate.
쐇 Use a pencil to mark the mounting holes. See Fig. 2.
쐋 Remove the wallplate from the wall and drill two
3/16 inch holes in the wall (if drywall) as marked. For
firmer material such as plaster or wood, drill two
7/32 inch holes. Gently tap anchors (provided) into
the drilled holes until flush with the wall.
69-0959
M6530
CAUTION
Disconnect power before wiring to prevent
electrical shock or equipment damage.
쐃 Loosen the terminal screws on the wallplate and
connect the system wires. See Fig. 6.
IMPORTANT
Use 18 gauge, color-coded thermostat cable for
proper wiring.
쐇 Securely tighten each terminal screw.
쐋 Push excess wire back into the hole.
쐏 Plug the hole with nonflammable insulation to
prevent drafts from affecting the thermostat.
2
T8501A,B,C,D MICROELECTRONIC THERMOSTATS
M4826
FOR WRAPAROUND
INSERTION STRIP
7/16 IN. (11 MM).
FOR STRAIGHT
INSERTION STRIP
5/16 IN. (8 MM).
THERMOSTAT
T
2
OUTDOOR
TEMPERATURE
SENSOR
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
AVAILABLE ON SELECT MODELS.
2
CW
HEATING
RELAY OR
VALVE COIL
1
M4822
L1
(HOT)
L2
Fig. 3. Typical hookup in heat only application.
THERMOSTAT
2
COMPRESSOR
CONTACTOR
HEATING
RELAY OR
VALVE COIL
1
M4821
OUTDOOR
TEMPERATURE
SENSOR
COOL
CHANGEOVER
VALVE OR
DAMPER
HEAT
CHANGEOVER
VALVE OR
DAMPER
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
AVAILABLE ON SELECT MODELS.
2
FAN
RELAY
ROTO
ROTOTCBOGYW
L1
(HOT)
L2
THERMOSTAT
T
OGYC BW
Rc
2
OUTDOOR
TEMPERATURE
SENSOR
COMPRESSOR
CONTACTOR
FAN
RELAY
COOL
CHANGEOVER
VALVE OR
DAMPER
1
L1
(HOT)
L2
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
AVAILABLE ON SELECT MODELS.
2
3
JUMPER Rh TO Rc IN A SINGLE TRANSFORMER SYSTEM.
Fig. 5. Typical hookup in heat and cool
system with two transformers.
HEAT
CHANGEOVER
VALVE OR
DAMPER
HEATING
RELAY OR
VALVE COIL
1
M4820
3
RhOTO
L1
(HOT)
L2
Fig. 4. Typical hookup in heat and cool
system with one transformer.
Mounting Thermostat
쐃 Engage tabs at the top of the thermostat and
wallplate. See Fig. 7.
쐇 Press lower edge of case to close and latch.
Fig. 6. Proper wiring technique.
3
69-0959
T8501A,B,C,D MICROELECTRONIC THERMOSTATS
A.
ENGAGE TABS AT TOP OF THERMOSTAT AND WALLPLATE.
B.
PRESS LOWER EDGE OF CASE TO LATCH.
Fan settings control the system fan as follows:
On: Fan operates continuously.
Auto: Equipment controls fan.
The system default setting is Heat and the fan default
setting is Auto. Use the keyboard or system and fan
switches, depending on model, to change to the desired
settings. See Figs. 9 and 10.
i
HEAT OFF COOL
ON AUTO
SYSTEM
Selection for heating or cooling
equipment operation.
Heat - Heating equipment
Off - No equipment
Cool - Cooling equipment
HEAT OFF COOL
ON AUTO
FAN
On - Fan runs continuously
Auto - Fan runs when
heating or cooling
equipment operates
M6798A
Fig. 7. Mounting thermostat on wallplate.
NOTE: To remove the thermostat from the wall, first pull out
at the bottom of the thermostat; remove top last.
Using Thermostat Keys
The thermostat keys are used to:
• set temperature,
•display present setting,
• configure Installer Setup,
• check Self-Test,
•display outdoor temperature (select models).
Select models have keys to:
• set the system operation,
• set the fan operation.
See Fig. 8 for key information.
INCREASE
TEMPERATURE
SETTING
i
DECREASE
TEMPERATURE
SETTING
DISPLAY PRESENT
SETTINGS AND SCROLL
THROUGH INSTALLER
SETUP MODES
(INFORMATION KEY)
M6801
Fig. 8. Thermostat key locations and descriptions.
SETTINGS
System and Fan Settings
System settings control the thermostat operation as
follows:
Heat: The thermostat controls the heating.
Off: Both the heating and cooling are off.
Cool: The thermostat controls the cooling.
Auto: The thermostat automatically changes between
heating and cooling operation, depending on the
indoor temperature.
M10146
Fig. 9. T8501C system and fan switches location.
i
Fan
System
Press to select
Press to select
heating or cooling
heating or cooling
equipment.
equipment.
Em. Ht.
-Emergency heating
On— Fan runs continuously
Heat—Heating equipment
Auto—Fan runs when
Off — No equipment
Cool—Cooling equipment
Auto—Thermostat
automatically selects
heating and cooling
equipment.
CHECK LIGHT ON SELECT MODELS
1
heating or cooling
equipment operates
System
Fan
1
System
Fan
M10147
Fig. 10. T8501D system and fan keys location.
NOTE: Always press the system and fan keys with your
fingertip or similar blunt tool. Sharp instruments
like a pen or pencil point can damage the
keyboard.
Temperature Settings
The default setpoint for heat is 70°F (21°C) and for cool is
78°F (25.5°C). Press the increase ▲ or decrease ▼ key to
change the present setting. To change between heat and
cool, press the Information i key until the setting to be
changed appears.
INSTALLER SETUP
NOTE: For most applications, the thermostat factory-
settings do not need to be changed. Review the
factory settings in Table 2 and if no changes are
necessary, go to the Installer Self-Test section.
69-0959
4
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