The Massachusetts Clean Energy Center maintains a list of ground-source heat pump installers that participated in their former ground-source heat pump rebate program, which was available to electricity customers in communities served by Eversource and National Grid. CMLP customers are free to use installers that have participated in the MassCEC program.
The International Ground-Source Heat Pump Association and the New England Geothermal Professional Association maintain directories of GSHP professionals, including installers.
We suggest soliciting proposals from at least three ground-source heat-pump installers.
Keep in mind that for any type of home heating or cooling system to work well, it must be selected, sized, and installed properly. The low-cost installer may not be your best option.