Error Codes — Mysa for In-Floor Heating

If your Mysa for In-Floor Heating displays an error code, use this guide to identify the issue and resolve it.

Error Code Reference

H2 — Open Heating Circuit

The thermostat detects no heater load on the circuit.

Possible causes:

• Heating mat not connected

• Loose wire connection

• Damaged heating element

How to fix:

1. Turn off power at the breaker

2. Check that the heating mat wires are securely connected to the LOAD terminals

3. Verify the heating mat is not damaged

4. Restore power and test

Warning Turn off power at the breaker before checking any wiring connections.

H3 — GFCI Trip

The built-in GFCI detected a ground fault and tripped for safety.

Possible causes:

• Ground fault in the heating mat

• Moisture in the electrical connections

• Damaged wiring

How to fix:

1. Press the Reset button on the side of the thermostat

2. If it trips again immediately, there may be a ground fault in the system

3. Check for moisture or damage in connections

4. Contact an electrician if the issue persists

Caution Repeated GFCI trips indicate a potential electrical fault. Do not bypass the GFCI. Have the system inspected by a qualified electrician.

I3 — Floor Sensor Issue

The floor sensor is not reading correctly.

Possible causes:

• Sensor wire disconnected

• Sensor damaged or broken

• Sensor resistance outside the 5K–40K Ohm range

How to fix:

1. Turn off power at the breaker

2. Check that the floor sensor wires are connected to the sensor terminals

3. Verify the sensor wire is not damaged

4. If using an existing sensor, confirm it's within the 5K–40K Ohm range

5. Recalibrate the sensor in app settings if needed

Tip If you installed a backup sensor during initial setup, you can switch to it without needing to access the floor.

Need Help?

Contact our support team at support@getmysa.com