DIY homeowner installed unit, 3 ton Carrier with 3 loops each 400 ft of 3/4'' poly buried about 6 ft deep. Home is 1500 ft2 2 story with basement, about 15 yrs old, well insulated and sealed.
In November 2020 installed a second geothermal unit, 3 ton with 4 loops 100' each with 400' 3/4'' slinky in each loop, in the work shop, there is also a wood boiler in there that can send hot water to the house