Landlord Thermostat (Ability to cap max temperature)

[Elvis Nasi]

For all my rentals that I am responsible for the utilities (especially gas), I am looking for a reasonably priced thermostat (heat only) that has an option to  cap the maximum temperature the tenant can set. They tend to abuse a lot in the winter and gas prices are up 40%+. There is some options here but the temperature does not seem to be adjustable (https://www.landlordthermostat...). I do not want to use the plastic boxes with keys as they are easy to break into. Thank you for any recommendations.