In case you've never seen the hole for a horizontal geothermal field

[HereSince1628]

5. It works pretty much as does a geothermal well...

...water with an anti-freeze in it is pumped from the field to the heat exchanger in the house--where its heat transfers to a refrigerant that when compressed releases heat...and cools the water--to a temperature at or just below freezing (iow the antifreeze isn't about being in the ground...but about the capacity of the compressor that is literally the heat pump. The space needed in the basement for the mechanicals is the same.

This field was about half the price of a vertical system of the same thermal capacity. Wells obviously fit better onto a smaller property.

People sometimes talk about geothermal without appreciating the potential size of 'the footprint'. When I first started looking into horizontal fields I was thinking about something like a large swimming pool not a fast food parking lot. The installers loved this site because it went under an ag field located on a drumlin (basically a low glacial hill of sand and gravel) that made the digging and backfilling easy...free of woody roots or boulders and freedom to pile the overburden. The entire footprint used during the install was the length of a football field and about half as wide.

This field will serve a three bedroom home with a full, heated basement...the house has ~2500 sq ft of heated/air-conditioned living space. Although it's built in southern Wisconsin, it's the building's 475 sq ft of south-facing solar absorbing glass and the potential for heat gain=cooling demand that actually pushed up the size of the system.