Johnson Controls T8490 Digital Room Thermostat with Humidity Control Manual

This thermostat has the ability to receive updates to its firmware. Periodically firmware updates are released by the manufacturer to add features and/or performance enhancements. This manual was produced reflecting the most current firmware/feature set at the time of publication, firmware rev. 12. Firmware releases after rev. 12 may not be adequately depicted in this manual. Please refer to the appropriate website or contact your place of purchase to learn about changes to the thermostat after firmware release 12.

Glossary of Terms

Auto-Changeover: A mode in which the thermostat turns on the heating or cooling based on room temperature demand.
Cool Setpoint: The warmest temperature that the space should rise to before cooling is turned on (without regard to deadband). Deadband: The number of degrees the thermostat will wait, once a setpoint has been reached, before energizing heating or cooling.
Dehumidify: To reduce the amount of moisture in the air.
Differential: The forced temperature difference between the heat setpoint and the cool setpoint. Heat Setpoint: The coolest temperature that the space should drop to before heating is turned on (without regard to deadband).
Humidify: To increase the amount of moisture in the air. Icon: The word or symbol that appears on the thermostat display. Mode: The current operating condition of the thermostat (i.e. Off, Heat, Cool, or Auto).
Non-Programmable Thermostat: A thermostat that does not have the capability to run Time Period Programming.
Override: During programmed unoccupied periods, pressing the Override button will force the thermostat into occupied settings. During programmed occupied periods, pressing the Override button will force the thermostat into unoccpied settings.
Programmable Thermostat: A thermostat that has the capability of running Time Period Programming.
Reheat: Runs the cooling and 2nd stage strip heaters at the same time in order to dehumidify the air without significantly cooling down the room temperature.
Time Period Programming: A program that allows the thermostat to automatically adjust the heat setpoint, or cool setpoint, based on the time of the day.

Display Features

Johnson Controls T8490 Digital Room Thermostat

Program icon - Indicates that Time Period Programming is running or is enabled to be set.
Clock with Day of the Week - Indicates the current time and day. This clock is also used to program the time period schedules.
Outdoor icon - Indicates the temperature displayed is from the optional outdoor sensor.
Room Temperature Display - Indicates the current room temperature and displays the outdoor temperature when selected.
Mode Indicators Selects the operational mode of the equipment.
1. HEAT - Indicates the heating mode.
2. COOL - Indicates the air conditioning mode.
3. HEAT & COOL - Indicates the system will automatically change-over between heat and cool modes as the temperature varies.
4. OFF - Indicates heating and cooling are turned off.
The scrolling display will be used to help you easily navigate the setup screens in the thermostat.
Occupied & Unoccupied icons - Indicates the program number: Occupied 1, 2, 3 or Unoccupied
2nd and 3rd Stage icons - Indicates what stage of cooling or heating is currently energized.
Setup Step icon - Indicates the step number when the thermostat is in the setup mode.
Desired Set Temperature - Indicates desired room temperature(s). Also displays the highest and lowest temperatures for the day.
Wi-Fi icons - One dot indicates the thermostat recognizes the wireless module. The full icon indicates the thermostat is currently connected to the Local access point, via the optional Wi-Fi Module.
Locked icon - Indicates the keypad has been locked.
Fan On icon - Indicates constant, continuous fan operation. When Fan On is not lit - indicates the fan will only operate when necessary to heat or to cool.
Lo icon - Indicates the lowest recorded outdoor temperature for the day.*
AuxHeat icon - Indicates 2nd stage electric strip heat is being used when the thermostat is programmed for Heat Pump operation. Only the Aux icon will appear during Cool to Dehumidify to indicate Reheat operation.
Hi icon - Indicates the highest recorded outdoor temperature for the day.* * Hi and Lo Temperatures for the day, reset at midnight.

Product Overview

The T8490 digital room thermostat serves a variety of commercial and residential HVAC applications; including packaged and split systems, gas and electric forced air systems, heat pumps and radiant heat. This flexible, multi-use thermostat supports up to four heating and two cooling stages. It can be independently programmed for each day (7-Day), for weekdays plus Saturday and Sunday (5/1/1), or for the same schedule every day (1-Day). It can also operate with no programmed schedule. The thermostat establishes separate setpoints for heating and cooling. Administrative settings can limit these setpoints to prudent minimum and maximum levels to ensure energy policy compliance.

Features

Up to Four Heating and Two Cooling Stages - Saves time and effort by standardizing operating procedures and minimizing inventory with this one flexible thermostat.
Humidity Sensor - Enables the device to control humidification, dehumidification, and reheat equipment.
Keypad Lockout - Enforces setpoint energy policies by preventing tampering with the digital room thermostat settings in public spaces.
Skyport Cloud Services (with Accessory Wi-Fi Module Sold Separately) - An accessory Wi-Fi module is available to plug into the T8490 thermostat to enable Skyport™ Cloud Services. This enables programming and configuration directly from the room thermostat or remotely from a mobile device or computer. This also allows for Automated Demand Response (ADR) signals from the local utility company. The T8490 complies with California Building Code, Title 24, Joint Appendix 5 (JA5) for Occupant Controlled Smart Thermostats (OCST).
Programmable (7-Day, 5/1/1, or 1-Day) Occupancy Schedule with up to Three Occupied Periods Each Day - Reduces operating expenses by controlling the room based on occupant schedules.
Configurable Alerts - Send messages to the digital room thermostat when certain conditions occur, such as equipment runtime and service alerts for filters, UV lamps, and humidifiers.
Multilingual Display Options - Provides a user interface in English, French, or Spanish.

Installation Instructions

Remove and Replace the Old Thermostat

To install the thermostat properly, please follow these step-by-step instructions. If you are unsure about any of these steps, call a qualified technician for assistance.

Assemble tools: Flat-blade screwdriver, wire cutters, and wire strippers.
Make sure your Heater/Air Conditioner is working properly before beginning installation of the thermostat.
Carefully unpack the thermostat. Save the screws, any brackets, and instructions.
Turn off the power to the Heating/Air Conditioning system at the main fuse panel. Most residential systems have a separate breaker for disconnecting power to the furnace.
Remove the cover of the old thermostat. If it does not come off easily, check for screws.
Loosen the screws holding the thermostat base or subbase to the wall and lift away.
Use a smart phone or mobile device to take a photo of the wiring for future reference.
Disconnect the wires from the old thermostat. Tape the ends of the wires as you disconnect them, and mark them with the letter of the terminal for easy reconnection to the new thermostat.
Keep the old thermostat for reference purposes, until your new thermostat is functioning properly.

Wire Connections

If the terminal designations on your old thermostat do not match those on the new thermostat, see the chart below or the wiring diagrams that follow.

Wire from the old thermostat terminal marked	Function	Install on the new thermostat connector marked
G or F	Fan	G
Y1, Y	Cooling	Y1
W1, W	Heating	W1/0/B
Rh, R, M, Vr, A	Power	R
C	Common	C
O/B	Rev. Valve	W1/O/B*
W2	2nd Stage Heat	W2
Y2	2nd Stage Cooling	Y2
W3	3rd Stage Heat	W3
H, Hum	Humidity	HUM
D, Dehum	Dehumidity	DEHUM
Ck1	Dry Contact Switch	DRY CONTACT
CKGND	Dry Contact Switch	DRY CONTACT

Title	: Johnson Controls T8490 Digital Room Thermostat with Humidity Control Manual
Format	: PDF
Pages	: 57 Pages
Language	: English
File Size	: 5.5 MB

Johnson Controls T8490 Digital Room Thermostat with Humidity Control Manual