American Standard Thermostat ACONT850 Manual

The American Standard ACONT850 is a programmable thermostat designed for residential heating and cooling systems. It features a backlit digital display, 7-day programming flexibility, automatic changeover between heating and cooling modes, temperature hold functions, filter change reminders, and system diagnostics. Compatible with most 24VAC HVAC systems including single-stage and multi-stage configurations. Below are key sections for safety, features, installation, programming, operation, and troubleshooting.

Features at a Glance

Key components: Backlit LCD display, Menu buttons, System switch, Fan switch, Hold button, Up/Down temperature arrows.

Installation

Turn off power to HVAC system before installation. Remove old thermostat and prepare wall plate.

1. Mount new wall plate: Use provided screws and level for proper alignment.
2. Connect wires: Match wire labels to terminal designations (R, C, W, Y, G, etc.).
3. Attach thermostat: Snap onto wall plate until it clicks into place.
4. Restore power and configure settings.

WARNING! Electrical shock hazard. Always turn off power at circuit breaker before installation. If unsure, consult professional HVAC technician.

First-Time Setup

After installation, restore power and follow initial setup prompts.

1. Set date and time: Use MENU button to access clock settings.
2. Configure system type: Select heat only, cool only, or heat/cool system.
3. Set temperature limits: Establish minimum and maximum temperature ranges.
4. Program schedule: Set weekday and weekend temperature programs.
5. Install batteries: Insert 2 AA alkaline batteries for backup power.

CAUTION! Ensure proper wire connections before restoring power. Incorrect wiring can damage thermostat or HVAC equipment.

Specifications

• Power Requirements: 24VAC from HVAC system; 2 AA battery backup
• Temperature Range: 40°F to 99°F (4°C to 37°C)
• Temperature Accuracy: ±1°F (±0.5°C)
• Display: Backlit LCD with temperature and status icons
• Programming: 4 periods per day, 7-day programmable
• Compatibility: Single and multi-stage conventional heat/cool systems
• Wiring Terminals: R, C, W, W2, Y, Y2, G, O/B, L
• Dimensions: 5.5" H × 3.5" W × 1" D (140mm × 89mm × 25mm)
• Operating Temperature: 32°F to 122°F (0°C to 50°C)
• Warranty: 5-year limited warranty

Controls and Settings

Front panel controls: MENU, SYSTEM (Heat/Off/Cool), FAN (Auto/On), HOLD, UP/DOWN arrows.

Menu Navigation: Press MENU to access programming, settings, and diagnostics.

System Settings: Heat/Cool/Auto selection, temperature limits, Fahrenheit/Celsius display. Programming: 4 time periods per day (Wake, Leave, Return, Sleep), separate schedules for each day. Advanced Settings: Filter change reminder interval (30-365 days), keypad lock, display brightness, system test mode.

Wiring Configuration

Standard terminal designations for HVAC system connections.

1. R (Red): 24VAC power from transformer
2. C (Blue/Black): Common/return 24VAC
3. W (White): Heat stage 1
4. W2 (Brown): Heat stage 2 (if applicable)
5. Y (Yellow): Cool stage 1
6. Y2 (Light Blue): Cool stage 2 (if applicable)
7. G (Green): Fan relay
8. O/B (Orange): Heat pump reversing valve
9. L (Clear): System status indicator

Tip: Take photo of old thermostat wiring before removal for reference. Label wires with provided stickers.

Programming Schedule

Create custom temperature schedules for energy savings and comfort.

1. Press MENU and select PROGRAM SCHEDULE
2. Select day (MON-SUN) to program
3. Set four periods: Wake (6:00 AM), Leave (8:00 AM), Return (6:00 PM), Sleep (10:00 PM)
4. Adjust temperatures for each period using UP/DOWN arrows
5. Copy schedule to other days if desired
6. Press DONE to save and exit

Energy Saving Tips: Set temperatures 7-10°F lower when sleeping or away. Use automatic scheduling rather than constant HOLD function.

System Diagnostics

Access diagnostic information through MENU > SYSTEM STATUS.

Display shows: Current system mode, set temperature, room temperature, filter status, battery level, error codes. Common error codes: E1 - Temperature sensor fault, E2 - System communication error, E3 - Power loss detected, E4 - Configuration error.

Care & Maintenance

Clean display with soft, dry cloth. Do not use liquids or cleaners. Replace batteries annually or when low battery icon appears. Replace air filter when reminder appears or according to manufacturer recommendations.

CAUTION! Never spray cleaning solutions directly on thermostat. Turn off power before cleaning around unit.

Regulatory Information

FCC Part 15: Class B digital device compliant. UL 873 certified for safety. Energy Star qualified. Copyright © American Standard Heating & Air Conditioning. For technical support, visit www.americanstandardair.com or contact 1-800-228-2962.

Troubleshooting

Reset: Press and hold MENU and DOWN arrow for 5 seconds to restore factory defaults.

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