American Standard Thermostat ASYSTAT 340 Manual

The American Standard ASYSTAT 340 is a programmable digital thermostat designed for residential heating and cooling systems. It features a backlit LCD display, 7-day programming capability, automatic changeover between heating and cooling modes, temperature hold functions, system status indicators, and compatibility with most 24VAC HVAC systems. Below are key sections for safety, features, installation, programming, operation, and troubleshooting.

1. Features at a Glance 2. Installation 3. First-Time Setup 4. Specifications 5. Controls and Settings 6. Connecting to HVAC System 7. Programming Schedule 8. Energy Saving Features 9. Care & Maintenance 10. Regulatory Information 11. Troubleshooting

Features at a Glance

Key components: Backlit LCD display, Mode buttons, Fan control, Program schedule buttons, Temperature adjustment arrows, System status indicators.

Feature	Description
7-Day Programming	Set different schedules for each day of the week
Automatic Changeover	Automatically switches between heating and cooling based on setpoint
Temperature Hold	Temporarily override programmed schedule
Backlit Display	Easy reading in low light conditions
System Status Indicators	LEDs for heating, cooling, and fan operation
Battery Backup	Maintains programming during power outages
Filter Change Reminder	Programmable alert for HVAC filter maintenance
Keypad Lock	Prevents unauthorized programming changes
Temperature Display	Shows current room temperature and setpoint
Compatibility	Works with most 24VAC heating and cooling systems

Installation

Turn off power to HVAC system before installation. Remove old thermostat carefully.

Mount backplate: Use included screws to secure backplate to wall.
Connect wires: Match wire labels (R, W, Y, G, C, etc.) to terminal screws.
Attach thermostat: Align and snap onto backplate.
Restore power and configure settings.

WARNING! Always turn off power at circuit breaker before installation to prevent electrical shock. Ensure proper wire labeling.

First-Time Setup

After installation, power on thermostat and configure initial settings.

Set mode: Press MODE to select HEAT, COOL, AUTO, or OFF.
Set fan: Press FAN for AUTO or ON continuous operation.
Set time and day: Use PROGRAM button to enter time/day settings.
Configure temperature limits: Set minimum and maximum temperature ranges.
Install batteries: Insert 2 AA batteries for backup power.

CAUTION! Do not force wires into terminals. Ensure connections are tight but not over-tightened.

Specifications

Power Requirements: 24VAC from HVAC system; 2 AA battery backup.
Temperature Range: Heating: 40°F to 90°F (4°C to 32°C); Cooling: 50°F to 99°F (10°C to 37°C).
Display: Backlit LCD with temperature and system status.
Programming: 7-day, 4 periods per day programmable.
Compatibility: Single-stage heating and cooling systems; conventional or heat pump.
Temperature Accuracy: ±1°F (±0.5°C).
Operating Environment: 32°F to 122°F (0°C to 50°C); 0-90% RH non-condensing.
Warranty: 5-year limited warranty from date of purchase.

Controls and Settings

Front panel controls: MODE, FAN, PROGRAM, HOLD, UP/DOWN arrows, DISPLAY button.

Display indicators: HEAT, COOL, FAN ON, HOLD, BATTERY LOW, FILTER.

Settings menu: Press PROGRAM to access time/day, temperature limits, filter reminder interval, keypad lock, temperature display (Fahrenheit/Celsius), system test. Programming: Set up to 4 temperature periods per day (Wake, Leave, Return, Sleep). Energy savings: Adaptive recovery, temperature setbacks, vacation hold.

Connecting to HVAC System

Terminals: R (24VAC power), W (Heat), Y (Cool), G (Fan), C (Common), O/B (Heat pump reversing valve).

Turn off HVAC system power at circuit breaker.
Label existing thermostat wires before disconnecting.
Connect wires to matching terminals on ASYSTAT 340 backplate.
For heat pump systems: Connect O/B wire if applicable.
Snap thermostat onto backplate and restore power.

Tip: Take photo of old thermostat wiring before removal for reference.

Programming Schedule

Create custom temperature schedules for energy efficiency.

Press PROGRAM button to enter programming mode.
Select day: Use arrows to choose day or copy to other days.
Set periods: Program up to 4 periods per day with desired temperatures.
Set times: Adjust start time for each period.
Review schedule: Scroll through periods to verify settings.
Exit programming: Press PROGRAM again to save and exit.
Temporary override: Press HOLD to maintain current temperature until next period.
Vacation mode: Set extended hold period for away times.

WARNING! Do not set temperatures too extreme; maintain reasonable differential from outdoor temperature.

Energy Saving Features

Adaptive Recovery: Learns system recovery time to reach setpoint by scheduled time. Temperature Setbacks: Program lower heating/higher cooling temperatures when away or sleeping. Filter Change Reminder: Program interval (30-365 days) to maintain system efficiency. System Cycling: Optimizes run times for comfort and efficiency.

Care & Maintenance

Clean display with soft, dry cloth only. Do not use liquids or cleaners. Replace batteries annually or when low battery indicator appears. Check wire connections periodically for corrosion or looseness.

CAUTION! Do not spray cleaning fluids directly on thermostat. Keep away from direct sunlight and heat sources.

Regulatory Information

FCC Part 15: Class B digital device; complies with interference limits for residential use. UL Listed: Meets safety standards for thermostats. Copyright © American Standard Heating & Air Conditioning. For support, visit www.americanstandard.com or contact 1-800-628-4516. Installation should be performed by qualified HVAC technician.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Blank display	Power loss/batteries	Check circuit breaker; replace batteries; verify 24VAC at R and C terminals.
System not turning on	Mode setting/wiring	Ensure correct mode selected; check wire connections at thermostat and HVAC unit.
Incorrect temperature reading	Location/calibration	Relocate away from heat sources; allow 15 minutes for stabilization; check calibration.
Schedule not following program	Hold active/programming	Cancel HOLD function; verify program times and temperatures; reset to factory defaults.
Short cycling	Temperature differential	Adjust temperature differential in installer settings (consult manual).

Reset: Press and hold PROGRAM and UP arrow for 5 seconds to restore factory defaults.

Service: 1-800-628-4516; www.americanstandard.com