Can Mysa Smart Thermostat use auxiliary heat as the primary heat source?

Mysa Smart Thermostat can support auxiliary heat on compatible heat pump systems, but it is designed to use auxiliary heat as a backup or staged heat source. It does not provide a separate control mode that makes auxiliary heat the normal primary heat source while keeping the heat pump as a secondary source.

What Mysa can do

• Control many compatible 24 V heat pump and conventional HVAC systems.

• Send a fan signal with heating or cooling calls when the selected system configuration supports it.

• Automatically stage auxiliary heat on supported heat pump configurations when the temperature difference or runtime threshold is met.

What Mysa cannot do

• Use an auxiliary heat terminal as the everyday primary heat call while treating the heat pump as secondary.

• Give separate app control to choose “hot-water coil only,” “aux only,” or “heat pump only” as independent heating sources.

• Guarantee compatibility for systems where an accessory, hydronic coil, or other auxiliary source must be controlled independently from the heat pump sequence.

If your system has a separate hot-water coil or unusual auxiliary heat

Some air handlers can be adapted to standard 24 V thermostat wiring while also having a separate hot-water or auxiliary heating source. Mysa Support can review the wiring to confirm what parts of the system may be compatible. If your goal is to make the auxiliary or hydronic heat source the main heat source, you may need a separate thermostat or control strategy for that heat source.

What to send Mysa Support

• A photo of the current thermostat wiring.

• The heating/cooling equipment model numbers.

• Whether the system is a heat pump, conventional system, fan coil, or mixed/hydronic setup.

• A short description of which heat source you want to run first and which should run only as backup.