According to HUD archive from 2012
https://archives.HUD.gov/offices/hsg/sfh/ref/sfhp1-26.cfm
C: Heating:
https://www.HUD.gov/sites/dfiles/OCHCO/documents/4000.1hsgh-011823.pdf
Heating and Cooling Systems
The Appraiser must examine the heating system to determine if it is adequate for healthful and comfortable living conditions, regardless of design, fuel or heat source. The Appraiser must notify the Mortgagee of the deficiency of MPR or MPS if the permanently installed heating system does not:• automatically heat the living areas of the house to a minimum of 50 degrees Fahrenheit in all GLAs, as well as in non-GLAs containing building or system components subject to failure or damage due to freezing;• provide healthful and comfortable heat or is not safe to operate;• rely upon a fuel source that is readily obtainable within the subject’s geographic area;• have market acceptance within the subject’s marketplace; and• operate without human intervention for extended periods of time. Central air conditioning is not required but, if installed, must be operational. If the air conditioning system is not operational, the Appraiser must indicate the level of deferred maintenance, analyze and report the effect on marketability, and include the cost to cure.
https://archives.HUD.gov/offices/hsg/sfh/ref/sfhp1-26.cfm
C: Heating:
- 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.
https://www.HUD.gov/sites/dfiles/OCHCO/documents/4000.1hsgh-011823.pdf
Heating and Cooling Systems
The Appraiser must examine the heating system to determine if it is adequate for healthful and comfortable living conditions, regardless of design, fuel or heat source. The Appraiser must notify the Mortgagee of the deficiency of MPR or MPS if the permanently installed heating system does not:• automatically heat the living areas of the house to a minimum of 50 degrees Fahrenheit in all GLAs, as well as in non-GLAs containing building or system components subject to failure or damage due to freezing;• provide healthful and comfortable heat or is not safe to operate;• rely upon a fuel source that is readily obtainable within the subject’s geographic area;• have market acceptance within the subject’s marketplace; and• operate without human intervention for extended periods of time. Central air conditioning is not required but, if installed, must be operational. If the air conditioning system is not operational, the Appraiser must indicate the level of deferred maintenance, analyze and report the effect on marketability, and include the cost to cure.