There are about 700,000 Ground Source Heat Pumps (GSHP), also called Geothermal Heat Pumps, installed in the US, but the industry says the potential is for 100 million eventually. Every state in the country is suitable for GSHP, although the installations vary according to local soil moisture conditions and some other factors.
Yesterday, I co-led a workshop at the annual meeting and expo of the National Ground Water Association, in Las Vegas, that covered web-based information available from state geological surveys that are of particular value to water well drillers. A focus of our discussion was on data we are gathering nationwide on Ground Source Heat Pump factors for inclusion in the National Geothermal Data System. This includes installation reports, thermal conductivities, heat flow and gradients, soil moisture, among others.
Afterwards, I had some time to meet with geothermal experts in NGWA and the International Ground Source Heat Pump Association (IGSHPA). Both have training and accreditation or certification programs for drillers and installers of geothermal heat pumps. You can find lists online of those professionals in Arizona who are IGSHPA certified installers.