I have a new thermostat but when I turn it up to 70 to get t to kick on it won't kick back off till its turned back down below 50. I don't know anything about this unit it was in the trailer when we bought it a few months ago. We were told it works and it does keep the house warm.

Did it work before you changed out the thermostat? Is it gas or electric heat? Its hard to answer the question with out knowing what you have. The more info you give the quicker your problem will be solved.