This is from the FHA website

C: Heating:
1. General: ALL habitable rooms must have a heat source. This does not mean that each room must contain a heating device but that each room must receive sufficient heat. (Exception: Homes located in the Caribbean, Hawaii and the Florida counties of Lee, Charlotte, Glades, Hendry, Palm Beach, Collier, Broward, Monroe and Miami-Dade do not require heat if, the lack of, is "typical" for the market area and does not adversely affect the marketability of the property.
2. Wood Stoves and Solar Systems: Dwellings with wood burning stoves or solar systems as a primary heat source must have permanently installed conventional heating systems that can maintain at least 50 degrees Fahrenheit in all living areas and those containing plumbing systems. These systems must be installed in accordance with the manufacturer’s recommendations.

3. Floor Heaters: Due to the inherit dangers of a floor heater it is highly recommended that floor heaters in need of repair be replaced with another permanent heat source.

4. Non-Conventional Heating Systems: All non-conventional heating systems, such as space heaters and others, must comply with local jurisdictional guidelines. Often these are not acceptable as the primary source of heat.

5. Propane tanks must be a safe distance from the dwelling. Leased tanks are acceptable when not offered for sale. Propane fired furnaces located in a crawl space area is not acceptable.