Configuring Your Mysa Smart Thermostat

Last updated: June 11, 2026

Configuring Your Mysa Smart Thermostat

Configuration codes tell your Mysa Smart Thermostat (formerly Mysa for Central HVAC) how to control your specific HVAC system. The correct code ensures heating, cooling, fan, and heat pump functions work properly.

Finding Your Configuration Code

Best method: Use the Mysa app during setup — it walks you through selecting your system type and automatically determines the right code.

Manual lookup: Visit mysacodefinder.com to find your code based on your system type.

How Configuration Codes Work

Each code is 3 characters:

  • First character: Heating type

  • Second character: Cooling type (and fan coil modes)

  • Third character: Heat pump, fan, and emergency heat options

Common Configuration Codes

Conventional Systems — HVAC Controls Fan

System

Code

1 heat / 1 cool

11A

2 heat / 1 cool

61A

2 heat / 2 cool

66A

Conventional Systems — Thermostat Controls Fan

System

Code

1 heat / 1 cool

11B

2 heat / 1 cool

61B

2 heat / 2 cool

66B

Heat Pump — HVAC Controls Fan

System

Code

1H/1C, no AUX, RV on cool

31M

1H/1C, no AUX, RV on heat

31I

2H/1C, with AUX, RV on cool

31O

2H/1C, with AUX, RV on heat

31K

2H/2C, no AUX, RV on cool

86M

2H/2C, no AUX, RV on heat

86I

Heat Pump — Thermostat Controls Fan

System

Code

2H/1C, with AUX, RV on cool

31P

2H/1C, with AUX, RV on heat

31L

3H/2C, with AUX, RV on cool

86P

3H/2C, with AUX, RV on heat

86L

Fan Coil Units

System

Code

2-pipe FCU (3-speed)

45B

Entering Your Code

Option 1: Through the Mysa App (Recommended)

  1. Open the Mysa app and tap Add Mysa

  2. Select No when asked if your thermostat is installed — this starts the configuration flow

  3. Follow prompts to select your connected wires and system type

  4. The app determines and sends the correct code automatically

Option 2: Manual Entry on the Thermostat

  1. Hold both arrow buttons to enter the Preferences Menu (PREF displays)

  2. Scroll right until CONF appears

  3. Use up/down arrows to enter your 3-character code

  4. Tap the center to confirm

Viewing or Changing Your Code Later

In the Mysa app: Device Settings → Thermostat Configuration

Your current code displays here, and you can update it if needed.

Supported System Types

  • Forced air: Gas or electric furnace with central AC (R, C, W, Y, G)

  • Boiler/radiant: Hydronic heating (R, C, W)

  • Dual systems: Boiler for heat + separate AC (Rh, Rc, C, W, Y, G)

  • Heat pumps: With or without auxiliary heat (R, C, Y, O/B, G, W/AUX)

  • Fan coil/PTAC: Multi-speed fan control (R, C, Y, W, G1/G2/G3)

Note Advanced configurations like aux heat staging are set in the Mysa app after initial setup.

When to Get Help

Contact Mysa support if:

  • Your system has two transformers (separate heating and cooling)

  • You have unlabeled or non-standard terminals

  • You're connecting to a boiler with dry contacts (T/T terminals)

  • The system behaves unexpectedly after trying different codes

Tip A photo of your control board helps our team confirm wiring remotely.

Need Help?