Instruct: Classify Amazon reviews into positive or negative sentiment
Query: defective engineering

This item was designed improperly. The high setting allows the heater to operate for no more than 10 minutes before the built-in "overheat" safty device shuts down the heater; after which, you would then have to manually reset it by unplugging and replugging it into the wall outlet. I am not sure exactly where the engineers placed the safety cut-off device but maybe they have it installed too close to the quartz tube behind the reflective metal sheet. How can the heater warm up the room if it keeps cutting off the power everytime the heater gets hot.