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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.
T8501
System
Changeover
A
Heat only
B
Heat only
C
Heat-Cool
D
Heat-Cool
Automatic
RECYCLING NOTICE
If this control is replacing a control that contains
mercury in a sealed tube, do not place your old
control in the trash.
Contact your local waste management authority for
instructions regarding recycling and the proper
disposal of the old thermostat.
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. •
Microelectronic Thermostats
Table 1. Description of T8501 Thermostats.
System
Selection
None
None
None
Heat-Off
Manual
Heat-Off-Cool
Heat-Off-Cool-Auto
• All Rights Reserved
T8501A,B,C,D
INSTALLATION INSTRUCTIONS
Fan
Selection
None
On-Auto
Select models have only a system switch or fan
switch and some models have both.
On-Auto
System and fan selections are done by
switches.
On-Auto
System and fan selections are done by
keyboard.
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.
Position and level the wallplate (for appearance
only). The thermostat will function properly even
when not level.
X-XX UL
Comments
—
69-0959
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Table of Contents
Related Manuals for Honeywell t8501A
Summary of Contents for Honeywell t8501A
-
Page 1: Wallplate Installation
4. After completing installation, use these instructions Position and level the wallplate (for appearance to check out the product operation. only). The thermostat will function properly even when not level. 69-0959 Copyright © 1996 Honeywell Inc. • • All Rights Reserved X-XX UL... - Page 2 T8501A,B,C,D MICROELECTRONIC THERMOSTATS 5 FEET [1.5 METERS] M10106 Fig. 1. Typical location of thermostat. Position the wallplate over the holes, pulling wires through the wiring opening. WALL Loosely insert the mounting screws into the holes. WIRES THROUGH WALL Tighten mounting screws.
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Page 3: Mounting Thermostat
T8501A,B,C,D MICROELECTRONIC THERMOSTATS THERMOSTAT THERMOSTAT OUTDOOR HEATING TEMPERATURE RELAY OR OUTDOOR SENSOR VALVE COIL TEMPERATURE SENSOR HEAT CHANGEOVER VALVE OR DAMPER HEATING (HOT) COMPRESSOR RELAY OR CONTACTOR VALVE COIL POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. RELAY M4822 AVAILABLE ON SELECT MODELS. -
Page 4: Using Thermostat Keys
T8501A,B,C,D MICROELECTRONIC THERMOSTATS ENGAGE TABS AT TOP OF THERMOSTAT AND WALLPLATE. 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. - Page 5 T8501A,B,C,D MICROELECTRONIC THERMOSTATS The Installer Setup is used to customize the thermostat to Em Ht Temporary Setting Remote specific systems. Some of the options include temperature Aux Ht Room display, changeover, minimum equipment on time and %Humid minimum off time. Installer modes are listed in numerical order in Table 2.
- Page 6 T8501A,B,C,D MICROELECTRONIC THERMOSTATS Table 2. Thermostat Installer Setup Options (continued). Other Choices Mode Display (Press key to change) Factory-Setting (Press i key to change) Select Display Description Display Description Not used — — — — Degree tempera- Temperature is Temperature is displayed in °C ture display displayed in °F...
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Page 7: Installer Self-Test
System key or system switch position test Press and hold the increase and decrease keys, at (not available on T8501A) the same time, until two zeros appear. All segments of the LCD are displayed before the two zeros appear. 70-79... -
Page 8: Thermostat Information
T8501A,B,C,D MICROELECTRONIC THERMOSTATS Table 4. Installer Self-Test Options. (Continued) Test Key to Mode Press Number Description Key or Switch Operation Self-Test IMPORTANT Test Mode Numbers will only be displayed when the system is configured for the selected function. EXAMPLE: Numbers 60, 61 and 62 are the only numbers that will be displayed when a system is configured for heat only. -
Page 9: Troubleshooting Guide
T8501A,B,C,D MICROELECTRONIC THERMOSTATS CHECKOUT Press the increase key again to display the EEPROM identification code. (Example: 222 = EEPROM ID 222) Outdoor Temperature Sensor (Where Applicable) Allow the outdoor temperature sensor to soak in the outdoor air for a minimum of five minutes before taking a reading. - Page 10 T8501A,B,C,D MICROELECTRONIC THERMOSTATS TROUBLESHOOTING GUIDE (Continued) Symptom Possible Cause Action Heating will not Thermostat minimum off time is Wait up to five minutes for the system to respond. come on. activated. (Continued) System selection is not set to Set system selection to Heat.
- Page 11 T8501A,B,C,D MICROELECTRONIC THERMOSTATS 69-0959...
- Page 12 T8501A,B,C,D MICROELECTRONIC THERMOSTATS Home and Building Control Home and Building Control Honeywell Inc. Honeywell Limited-Honeywell Limitée Honeywell Plaza 155 Gordon Baker Road P.O. Box 524 North York, Ontario Minneapolis, MN 55408-0524 M2H 2C9 69-0959 69-0959 J.H. 10-96 Printed in Taiwan R.O.C.