From what I have been reading, there are two ways that the Wyze Thermostat controls the Aux & Emergency Heat. Aux Automatically or Emergency Manually.
If connected to the " W1 " lug on the thermostat, it will control the backup as Aux Heat Automatically and turn it on if the heat pump can’t achieve set temp (+ differential) within 30 minutes or if the temp delta between the measured temp and target set temp is +5°.
If connected to the " * " lug, it would operate the backup manually as Emergency Heat, but there are drawbacks to this mentioned below:
If jumpered, it could theoretically be used in both situations, but would need to be tested to confirm.
But, both must be specifically designated when doing the wiring setup on install.
@speadie would be best to verify my understanding of this though as it was their post that brought me to this conclusion. Because the OP had electric EH, it may be different and Speadie is the expert here.
W1 would have it operate automatically, “*” has it operate when emergency heat is on. but the wyze’s implementation of emergency heat is rather poor, it appears to disable the thermostat’s temperature control and it’s just an on or off switch.
So I have them designated backwards above. The W1 is the automatic timed Aux and the * is the emergency heat with the caveat that when activated in the app it disables the temp control until deactivated in the app?