American Standard Thermostat CeraTherm R520 Manual

The American Standard CeraTherm R520 is a programmable electronic thermostat designed for residential heating and cooling systems. It features a ceramic temperature sensor for accurate readings, 7-day programming flexibility, large backlit display, system status indicators, and compatibility with most 24VAC single-stage 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. Wiring Configuration 7. Programming Schedules 8. System Operation 9. Care & Cleaning 10. Regulatory Information 11. Troubleshooting

Features at a Glance

Key components: Ceramic temperature sensor, large LCD backlit display, 7-day programmable schedule, system mode selection, fan control, and hold function.

FeatureDescription
Ceramic Temperature SensorProvides accurate and stable room temperature readings
7-Day ProgrammableAllows different schedules for each day of the week
Large Backlit DisplayEasy-to-read temperature and status information
System Mode SelectionHeat, Cool, Auto, and Off modes
Fan ControlAuto or On settings for continuous fan operation
Hold FunctionTemporarily overrides programmed schedule
Filter Change ReminderProgrammable alert for HVAC filter maintenance
Battery BackupMaintains settings during power outages (2 AA batteries)
System Status IndicatorsLEDs for heating, cooling, and fan operation
Temperature Range40°F to 99°F (4°C to 37°C)

Installation

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

  1. Remove old thermostat: Label wires before disconnecting.
  2. Mount subbase: Level and secure to wall using provided screws.
  3. Connect wires: Match labeled wires to corresponding terminals (R, W, Y, G, C, etc.).
  4. Attach thermostat: Align and snap onto subbase.
  5. Restore power: Turn circuit breaker back on.

WARNING! Electrical shock hazard. Always turn off power before installation. If unsure, consult a qualified HVAC technician.

First-Time Setup

After installation and power restoration, configure initial settings.

  1. Set time and day: Press SET CLOCK and adjust using arrow keys.
  2. Select temperature format: Choose Fahrenheit or Celsius in SYSTEM SETUP.
  3. Configure system type: Set for conventional or heat pump systems.
  4. Program schedules: Set up daily temperature programs (see Programming section).
  5. Install batteries: Insert 2 AA batteries for backup power.

CAUTION! Ensure correct system type configuration to prevent equipment damage.

Specifications

Controls and Settings

Front panel includes temperature display, mode buttons, and programming keys.

Buttons: MODE (Heat/Cool/Auto/Off), FAN (Auto/On), HOLD, SET CLOCK, PROGRAM, UP/DOWN arrows.

Settings Menu: Access by holding PROGRAM for 3 seconds. Options include temperature format (F/C), system type (conventional/heat pump), filter change reminder interval, and calibration offset.

Programming: 4 time/temperature periods per day (Wake, Leave, Return, Sleep).

Wiring Configuration

Standard terminal designations for HVAC system connections.

  1. R (Red): 24VAC power from transformer.
  2. W (White): Heat stage 1.
  3. Y (Yellow): Cooling stage 1.
  4. G (Green): Fan relay.
  5. C (Blue/Black): Common 24VAC return.
  6. O/B (Orange): Reversing valve for heat pumps (O for cooling, B for heating).

Tip: Take a photo of existing wiring before disconnecting old thermostat for reference.

Programming Schedules

Create custom temperature schedules for energy savings and comfort.

  1. Press PROGRAM button to enter programming mode.
  2. Select day or day group (Weekday, Weekend, or individual days).
  3. Set up to 4 periods per day with time and temperature settings.
  4. Use UP/DOWN arrows to adjust time and temperature values.
  5. Press PROGRAM to move between periods and days.
  6. Press DONE to save and exit programming mode.

Example Schedule: Wake (6 AM, 70°F), Leave (8 AM, 62°F), Return (5 PM, 68°F), Sleep (10 PM, 65°F).

System Operation

Daily use and temporary overrides.

Normal Operation: Thermostat follows programmed schedule automatically.

Temporary Override: Press HOLD to maintain current temperature until next scheduled period.

Manual Adjustment: Use UP/DOWN arrows to change temperature temporarily (reverts at next period).

System Mode: Use MODE button to select Heat, Cool, Auto (automatically switches between heat and cool), or Off.

Fan Control: Use FAN button for Auto (fan runs with heating/cooling cycles) or On (continuous operation).

Care & Cleaning

Turn off power before cleaning. Use soft, dry cloth only; do not use liquids or cleaners.

CAUTION! Do not spray liquids directly on thermostat. Keep away from moisture and heat sources.

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.americanstandardair.com or contact 1-800-428-4328.

Troubleshooting

SymptomPossible CauseCorrective Action
Blank displayPower loss or dead batteriesCheck circuit breaker; replace AA batteries.
System not respondingIncorrect wiring or mode settingVerify wiring connections; ensure correct MODE selection.
Inaccurate temperatureLocation or calibration issueRelocate away from heat sources; use calibration offset in settings.
Schedule not followingHold function active or programming errorCancel HOLD; review and reprogram schedule.
Short cyclingTemperature differential too smallAdjust cycle rate in advanced settings (if available).

Reset: Remove batteries and disconnect from HVAC power for 30 seconds to reset to factory defaults.

Service: 1-800-428-4328; www.americanstandardair.com

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