American Standard Thermostat Ceratherm T203.740 Manual

The American Standard Ceratherm T203.740 is a programmable thermostat designed for precise temperature control in residential heating and cooling systems. It features a digital display, multiple programming periods, temperature hold functions, system mode selection (Heat/Cool/Auto/Off), fan control, and battery backup. Below are key sections for safety, features, installation, setup, operation, and troubleshooting.

1. Features at a Glance 2. Installation 3. First-Time Setup 4. Specifications 5. Controls and Settings 6. Wiring Configuration 7. Programming Schedule 8. Energy Saving Tips 9. Care & Cleaning 10. Regulatory Information 11. Troubleshooting

Features at a Glance

Key components: Digital LCD display, Program buttons, System Mode selector, Fan control, Temperature hold, Battery compartment.

Feature	Description
Digital Display	Shows current temperature, time, and system status
Programmable Schedule	4 periods per day (Wake, Leave, Return, Sleep)
System Mode	Heat, Cool, Auto, Off selection
Fan Control	Auto or On continuous fan operation
Temperature Hold	Temporary or permanent override of programmed schedule
Battery Backup	Uses 2 AA batteries to retain settings during power loss
Filter Change Reminder	Programmable alert for HVAC filter maintenance
Keypad Lock	Prevents unauthorized changes to settings
Temperature Range	40°F to 99°F (4°C to 37°C)
Compatibility	Works with most 24VAC heating and cooling systems

Installation

Turn off power to HVAC system at circuit breaker before installation.

Remove old thermostat: Label wires, disconnect from terminals.
Mount new baseplate: Level and secure to wall using provided screws.
Connect wires: Match labeled wires to corresponding terminals (R, W, Y, G, etc.).
Attach thermostat: Align and snap onto baseplate.
Install batteries: Insert 2 AA batteries into compartment.
Restore power: Turn circuit breaker back on.

WARNING! Electrical shock hazard. Ensure power is OFF before handling wires. If unsure, consult a qualified HVAC technician.

First-Time Setup

After installation and power restoration, configure initial settings.

Set time and day: Press SET CLOCK button, use arrows to adjust.
Select temperature format: Press MENU, navigate to UNITS, select °F or °C.
Configure system type: In MENU > SYSTEM CONFIG, select 1H/1C (conventional) or Heat Pump if applicable.
Set filter reminder: Access MENU > FILTER, input days between changes (e.g., 90).
Program schedule: See Programming Schedule section for details.

CAUTION! Incorrect system configuration may cause equipment damage. Refer to HVAC system manual for correct settings.

Specifications

Power Supply: 24VAC from HVAC system; 2 AA battery backup.
Display: Backlit LCD.
Temperature Control Range: 40°F to 99°F (4°C to 37°C).
Setpoint Resolution: 1°F or 1°C.
Accuracy: ±1°F (±0.5°C).
Program Schedule: 7-day, 4 periods per day.
Compatibility: Single-stage conventional and heat pump systems (no multi-stage).
Operating Environment: 32°F to 105°F (0°C to 40°C), 0-90% RH non-condensing.
Wiring Terminals: R, Rc, W, Y, G, O/B, C (common).
Dimensions: 5.1" H x 3.3" W x 0.9" D (130mm x 84mm x 23mm).

Controls and Settings

Access functions via front buttons and MENU navigation.

Front Panel: UP/DOWN arrows, HOLD, FAN, SYSTEM (Mode), MENU, SET CLOCK, DONE.

Menu Settings: SYSTEM CONFIG (1H/1C, Heat Pump), UNITS (°F/°C), FILTER (reminder interval), KEYPAD LOCK (On/Off), FACTORY RESET.

System Modes: HEAT (heating only), COOL (cooling only), AUTO (system switches between heat and cool based on setpoints), OFF (system off).

Fan Modes: AUTO (fan runs only when heating/cooling is active), ON (fan runs continuously).

Wiring Configuration

Standard terminal designations for conventional systems:

R or Rc: 24VAC power from cooling transformer.
Rh: 24VAC power from heating transformer (jumper to Rc if single transformer).
W: Heat control signal.
Y: Cool/compressor control signal.
G: Fan control signal.
C: Common wire for continuous power (recommended).
O/B: Reversing valve for heat pumps (O for cool, B for heat).

Tip: Take a photo of old thermostat wiring before disconnecting. If C wire is not present, thermostat will operate on batteries but may require frequent changes.

Programming Schedule

Create a 7-day schedule with 4 periods per day.

Enter programming: Press MENU, select PROGRAM SCHEDULE.
Select day: Choose ALL DAYS, WEEKDAYS, WEEKEND, or individual day.
Set periods:
- WAKE: Morning temperature (e.g., 6:00 AM, 70°F).
- LEAVE: Daytime setback (e.g., 8:00 AM, 62°F Heat / 78°F Cool).
- RETURN: Evening temperature (e.g., 6:00 PM, 70°F).
- SLEEP: Nighttime setback (e.g., 10:00 PM, 65°F Heat / 75°F Cool).
Adjust times/temps: Use UP/DOWN arrows.
Save: Press DONE to exit and save.

Override: Press HOLD for temporary override (resumes schedule next period). Press HOLD again for permanent hold (until manually changed).

Energy Saving Tips

Use setbacks: Program lower heat temperatures when away/asleep; higher cool temperatures. Utilize AUTO mode: Let thermostat switch between heat and cool based on comfort range. Maintain filters: Change regularly per reminder for efficient airflow. Seal drafts: Ensure windows/doors are sealed to prevent energy loss.

Care & Cleaning

Unplug or turn off HVAC power before cleaning. Use soft, dry cloth to wipe display and casing. Do not use liquids, cleaners, or compressed air.

CAUTION! Do not spray any liquids into unit. Avoid abrasive materials that may scratch display.

Regulatory Information

FCC Part 15: Class B digital device; complies with interference limits for residential use. UL Listed. Copyright © American Standard Heating & Air Conditioning. For support, visit www.americanstandard.com or contact 1-800-228-2962.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Blank display	Dead batteries / No power	Replace batteries; check circuit breaker and wiring at HVAC unit.
System not turning on	Incorrect mode / Wiring	Ensure SYSTEM is set to HEAT or COOL; verify W or Y wire connection.
Incorrect temperature reading	Location / Drafts	Relocate thermostat away from heat sources, drafts, or direct sunlight.
Schedule not following program	Hold active / Clock error	Cancel HOLD function; verify correct time and day settings.
Short cycling	Temperature differential	Check HVAC equipment; ensure thermostat is not near vents causing rapid temperature change.

Reset: MENU > FACTORY RESET to restore default settings (erases all programming).

Service: 1-800-228-2962; www.americanstandard.com