Patrick, I have a few questions. 1) Based on 2000kwh used per month and a bill of $350 you are paying 17.5 cents per kw yes? 2) type of floor joist  system? 3) Do you have a ledgerboard and what is its make of? 4)Do you have two electrical meters on your house or just one? 5) Basement wall height? 6) first floor wall height? 7) mfg. of geo unit ?8) well capacity in liters per minute?9) window brand? 10) number of windows? 11) type of glazing ie.. thermal , low-e...? 12)please give more info on rusted bolts,where are they ,diameter,quanity. 13) have you changed your air filter?14) number of exterior doors and size? Your geo unit is not working properly. What you have discribed tells me the unit is cycling on a safty setting.The answers to the above questions will help.

other have told you the unit is oversized and the concerns of it short cycling like that.

i also want to add this is probly why you are seeing rusted bolts. the humidty level will never get under control with those short cycles. so you might want to look around for signs of other things besides just the rust like mold for example.