We don't use heat in homes here so I have to ask. Does the heat pump draw 50a or is it just a 50a breaker? We can't check your math with out all the information. Myself I'm not the best person to ask on calc's. Depending on who you ask you can have a different interpitation of how to figure it.
I can say that 3000 sf does not seem out of line for a 200a service. For friges most new ones don't draw that much. A lot of home now have a few friges/freezers around the house. The other thing to figure is do you have enough circuit space or do you need a sub.
If it is close you may tell the HO that and let them make the call.
Tom
