Diagnosis
An audible buzz from the thermostat indicates component vibration. This is often caused by a slightly loose wire connection on the high-voltage terminals, creating micro-arcing or vibration.
How to Fix It
Turn off the circuit breaker. Remove the Mysa faceplate. Firmly tighten the screws on the L (Line) and 1 (Load) terminals. Also check the N (Neutral) terminal. Do not overtighten. Reattach the faceplate and restore power.
If That Didn't Work
The buzz may be originating from the internal relay or transformer. This can be normal operational sound for some units, but it should be very faint. If loud, contact Mysa support.
Heads Up
A loud hum or crackling sound is not normal and indicates a dangerous fault. Power off the unit at the breaker immediately and inspect the wiring at the heater for damage.