What is the lowest temperature I can set the heat at?

Thank you for your question. This unit efficiently heats with outdoor temperatures ranging from -14 degrees Fahrenheit to 75 degrees Fahrenheit. It cools with outdoor temperatures ranging from 14 degrees Fahrenheit to 115 degrees Fahrenheit. For indoor temperature control, the unit heats between 70 degrees Fahrenheit and 80 degrees Fahrenheit; the unit cools between 57 degrees Fahrenheit and 90 degrees Fahrenheit. For more assistance, please give us a call.