Installation & Wiring Troubleshooting — Mysa for Baseboards

Last updated: September 2, 2026

Ran into a problem while installing Mysa for Baseboards? Work through the symptom that matches what you're seeing.

Warning Always turn off power at the breaker and confirm with a voltage tester before touching any wires.

Thermostat won't power on

  1. Remove the faceplate and look for a green LED on the base plate

  2. If no green LED: The L1 supply wire (usually black, from breaker) isn't connected to Mysa L1. Turn off power and check the connection.

  3. If green LED is lit: Mysa is receiving power. Remove the faceplate for 3–5 minutes, then reattach it. If the display still doesn't light up, contact support.

Heat won't shut off

This is often caused by the heater wire being connected to L1 instead of Load.

  • The L1 supply wire (usually black, from breaker) should connect to Mysa L1

  • Heater wires should connect between Mysa Load and L2/N — not to L1

Turn off power, review your wiring, and correct any mistakes. If the heater still won't shut off, contact support.

No heat coming from the heater

The most common cause is an incorrect connection between the heater load wire and Mysa Load.

  • Check that the heater load wire is securely connected to Mysa Load

  • Give the wire nut a gentle tug to confirm it's tight

H2 error code (V2 and V1 only)

Mysa didn't detect a heater between Load and L2/N.

  1. Turn off power at the breaker

  2. Check that all wires are properly secured in each wire nut — as more wires go into a wire nut, connections can loosen

  3. Turn power back on and verify the error clears

Reboot methods

If you need to restart your thermostat:

Soft reboot: Hold the up and down arrows (or buttons) for 10 seconds.

Hard reboot: Turn off the circuit breaker, wait 30 seconds, then turn it back on.

Still stuck?

Include a photo of your wiring and your heater's rating plate — it speeds up the answer considerably.