Heat Pumps and Electric Heating - Geothermal Controls

I have new Bryant 2-stage Geothermal Split Systems coupled with high-efficiency 3-stagefurnance/air handlers, using the Evolution Controls (it has NIM cards on the geothermal units for interface).. After the install I was provided the installation manuals and was very disappointed to find this isn’t a “state of the art” control system, at best the controls are currently written around air side heat pumps, using space and outside air temperatures for their logic. It doesn’t look at water temperatures for any decisions or alarms, nor can it make decisions on when to switch away from geothermal because of diminishing returns based on the use (or cost) of energy. Are there any add-on packages that can supplement the Evolution Controls, or is there a replacement control package that would do the job?

Geothermal units are usually the most efficient source of heat or at least more so than gas. Historically, the logic on geothermal units is based on air source logic because both apply. If the water return temperature is diminishing then the loop is not extracting the necessary heat from the ground. If it's simply a capacity issue, then your system should switch to gas based on outdoor temperature. The geothermal has safety limits on how low it will allow the ground loop temperature to dip.

If you find controls to do otherwise, they will ultimately do the same function. I would suggest to save your money and set the balance point temperature to achieve the results that you feel are important for the utility rates in your area.