We are renting a home and in a loft over the garage, the heat/cool Geotermal system will not shut off when temps are met, neither in the heat or cool or off settings, it runs continueously, we need to shut it down by tripping the circuit breaker, and then for some reason will not provide hot water from the Rinnai hot water system, for hot water we need to trip circuit breaker back on. What can it be? Why am I asking, we have not been able to get a HVAC guy out here.

First, have you talked to your landlord?
It sounds like the water heater is wired into the same circuit as the furnace, which is not a good thing, at all.
It also sounds like an electrical relay is malfunctioning on your HVAC. Find the HVAC company that did the original installation if possible, to service the unit, and soon.

Geothermal systems are often used to produce hot water. Perhaps your geothermal is running extra for the hot water? Typically the "desuperheater" part of the geothermal system is used to to preheat water that then goes to a hot water heater.