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

1 heat / 1 cool

Code11A

2 heat / 1 cool

Code61A

2 heat / 2 cool

Code66A

Conventional Systems — Thermostat Controls Fan

System	Code
1 heat / 1 cool	11B
2 heat / 1 cool	61B
2 heat / 2 cool	66B

1 heat / 1 cool

Code11B

2 heat / 1 cool

Code61B

2 heat / 2 cool

Code66B

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

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

Code31M

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

Code31I

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

Code31O

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

Code31K

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

Code86M

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

Code86I

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

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

Code31P

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

Code31L

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

Code86P

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

Code86L

Fan Coil Units

System	Code
2-pipe FCU (3-speed)	45B

2-pipe FCU (3-speed)

Code45B

Entering Your Code

Option 1: Through the Mysa App (Recommended)

Open the Mysa app and tap Add Mysa
Select No when asked if your thermostat is installed — this starts the configuration flow
Follow prompts to select your connected wires and system type
The app determines and sends the correct code automatically

Option 2: Manual Entry on the Thermostat

Hold both arrow buttons to enter the Preferences Menu (PREF displays)
Scroll right until CONF appears
Use up/down arrows to enter your 3-character code
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?

Email: install@getmysa.com
Code finder: mysacodefinder.com