If your wife likes it warm, a heat pump by itself will not make her happy, even one that uses water transfer. However a heat pump with a back up heat supply is a good combo, especially if ac is a requirement. Backup could be room like, ie stove, or whole house. Then you can use the charts above for BU. My significant other likes it warm and starts burning pellet stove in Oct. I have to restrict her to 4 tons of pellets a year. 30,000 BTU PS works fine since I have 1 story open floor plan. One day I'll figure out how to convert my 4 acres of woods into pellets cheaply instead of begging folks to take the fallen trees! When I get ready to replace HP, will reconsider diggin wells, but that's depends on number of wells (~3) and costs to drill them. Without BU, air from HP will not feel warm and forget about getting dampness out of the air. BTU's is for engineers, comfort factor is what women use! Remember if there not happy your not happy, no matter what the numbers say !!! As was stated if your windows and doors, and attic insulation has never been updated, first area to mod!