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X-XX UL

INSTALLATION INSTRUCTIONS

®U.S. Registered Trademark
Copyright © 1997 Honeywell Inc.  •            •   All Rights Reserved

T8524C,D Multistage

Microelectronic Thermostats

APPLICATION

The T8524C, D Multistage  Microelectronic Thermostat provides electronic control of 24 Vac two-stage heating and two-
stage cooling systems. Refer to Table 1 for a general description of the thermostat. All T8524 Thermostats require a
common wire to supply power.

Table 1. Description of T8524 Thermostats.

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.

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.

1. Position and level the wallplate (for appearance

only). The thermostat will function properly even
when not level.

T8524

System

Changeover

System  

Selection

Fan

Selection

Comments

C

Heat-Cool

Manual

Heat-Off-Cool

On-Auto

System and fan selections are done by
switches.

D

Heat-Cool

Automatic

Heat-Off-Cool-Auto

On-Auto

System and fan selections are done by
keyboard.

69-1055-1

Summary of Contents for DMULTISTAGE T8524C

Page 1: ... your application 3 Installer must be a trained experienced service technician 4 After completing installation use these instructions to check out the product operation 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 th...

Page 2: ...ews into the holes 6 Tighten mounting screws WIRING All wiring must comply with local electrical codes and ordinances Refer to Fig 3 for typical hookups A letter code is located near each terminal for identification CAUTION Disconnect power before wiring to prevent electrical shock or equipment damage 1 Loosen the terminal screws on the wallplate and connect the system wires See Fig 4 IMPORTANT Us...

Page 3: ...A B PRESS LOWER EDGE OF CASE TO LATCH A ENGAGE TABS AT TOP OF THERMOSTAT AND WALLPLATE M6801 DISPLAY PRESENT SETTINGS AND SCROLL THROUGH INSTALLER SETUP MODES INFORMATION KEY i DECREASE TEMPERATURE SETTING INCREASE TEMPERATURE SETTING Using Thermostat Keys The thermostat keys are used to set temperature display present setting configure Installer Setup check System Test display outdoor temperature...

Page 4: ...ting 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 System Test section The Installer Setup is used to customize the thermostat to specific systems Install...

Page 5: ...geover Not used 13 Degree temperature display 14 00 Temperature is displayed in F 01 Temperature is displayed in C Not used 15 thru 18 Extended fan operation in heatinga b 19 00 No extended fan operation after the call for heat ends 01 Fan operation is extended 90 seconds after the call for heat ends Extended fan operation in coolinga 20 00 No extended fan operation after the call for cool ends 01...

Page 6: ...nAuto System Fan Room Outdoor Em Ht Temporary Setting Wait Humid Aux Ht Remote Repl Batt M4844 M6792 TEST MODE NUMBER a Available on select models b T8524D is 48 F 9 C IMPORTANT Review the settings to confirm that they match the system INSTALLER SYSTEM TEST Use the Installer System Test to check the thermostat configurations and operation Refer to Table 3 for a list of the available system tests T...

Page 7: ...n T8524C 31 Stage one cool and system fan come on 32 Stage two cool comes on Stage one cool and system fan remain on 31 Stage two cool turns off 30 Stage one cool and system fan turn off Fan Equipment System test T8524D only i 40 Change from cooling to fan equipment system test 41 Fan comes on 40 Fan turns off Key or Switch Operation System test IMPORTANT Test Numbers will only be displayed when t...

Page 8: ...ill not come on Thermostat is not being powered Check that C terminal is connected to the system transformer Check for 24 Vac between C and R or RH terminals If missing 24 Vac check if the circuit breaker is tripped reset the circuit breaker check if the system fuse is blown replace the fuse check if the power switch on the HVAC equipment is in the Off position set to the On position check wiring ...

Page 9: ...pment replace any broken wires and tighten any loose connections If 24 Vac is present proceed with troubleshooting Thermostat minimum off time is activated Wait up to five minutes for the system to respond Enter Installer Setup mode number 33 Reconfigure minimum off time if required System selection is not set to Cool Set system selection to Cool Cooling setpoint is above room temperature Check co...

Page 10: ...69 1055 1 10 T8524C D MULTISTAGE MICROELECTRONIC THERMOSTATS ...

Page 11: ...69 1055 1 11 T8524C D MULTISTAGE MICROELECTRONIC THERMOSTATS ...

Page 12: ...ATS Home and Building Control Honeywell Limited Honeywell Limitée 155 Gordon Baker Road North York Ontario M2H 3N7 Home and Building Control Honeywell Inc Honeywell Plaza P O Box 524 Minneapolis MN 55408 0524 69 1055 1 J H Rev 6 97 www honeywell com yourhome ...

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