When sizing mini-splits for heating applications it can be confusing as to which unit is the right choice for the application. When we reference the heating point of 14, 5, -5, and -15 deg this is simply the point at which the nominal capacity is still above 80% and does not mean the unit will only run down to that temperature. The below chart gives a great overview of the heating output of each heat pump, allowing you to choose the right unit for the heating load. Taking some time looking through this chart will give you a decent understanding of which series and sizes are the best value. 

For more information on this topic please see this article: https://techsupport.jswmi.com/kb/article/557-minisplit-design/ 

To find more unit specific information, use the tech support portal and search the model number you are after: https://techsupport.jswmi.com/home/ or visit the Fujitsu connect site: https://connect.fujitsugeneral.com/home