Hi Dennis,

Yes, you can use a thermostat to operate the fireplace. To do so properly and safely, you'll need to determine the voltage to the switch that currently turns the fireplace on and off.

Once you know voltage, you would need to choose a heating thermostat (a cooling thermostat would only shut the fireplace off once it got colder) that is rated for a voltage that is equal to or greater than this voltage.

Swap the switch for the thermostat and you're done. Good luck!