Does this heater have a thermostat? Does the glass stain?

Please reference page 25 of SIERRA FLAME Lynwood W76 Installation Manual for how to properly clean the glass. This unit is not equipped with a thermostat, however, on pages 22 and 23 it instructs how to adjust the control arm to adjust the heat output. If you have any further questions or need further assistance, please feel free to reach out to one of our experienced customer service representative and they would be happy to assist you. Thank you and have a wonderful day.