Geothermal on a Columbia County acre: from the first phone call to the last loop, including what changed in the rules

Day one: the phone call and the question about your well

A geothermal inquiry from Columbia County almost always starts the same way: an acreage house toward Fort White, Columbia City or out SR 100 toward Lulu, a conventional heat pump on its second or third condenser, and an owner who is done watching lightning and pine straw eat outdoor units. The first question we ask is about the well, because the water under this county is hard, iron-bearing and often sulfurous, and that answer shapes the whole design.

Day three: the site walk and the karst question

We walk the property with a tape, a map and a soil probe. Lake City sits on karst, the limestone terrain that gives the region its springs and, occasionally, its sinkholes. Loop fields go where the ground is stable and away from any low spot that has ever held water oddly. On a few acres there is usually room for horizontal trenches, which cost less than vertical bores; on a smaller lot we drill. We also test the duct in the house, because a geothermal unit on leaky 1990s flex duct wastes the one thing you are paying for.

Three rule changes since the last geothermal boom

Three things, and they matter to what you buy now. First, efficiency ratings moved to the SEER2 and EER2 test standard, which measures equipment against more realistic duct resistance; an old rating and a new one are not directly comparable, so compare within the new standard only. Second, the industry has moved to lower-global-warming refrigerants, and current geothermal units are built for them; a unit still running the old refrigerant will get harder to service over its life. Third, the 25D residential geothermal credit is gone for any system that went live after 2025 closed. We will not promise it, and anyone who does is selling you last year.

Start the geothermal conversation

Closed loop over open loop, because of the iron

An open-loop system pumps well water through the heat exchanger and discharges it. On soft, clean water that can be the cheapest design. On Floridan aquifer water around Lake City it is a maintenance problem: iron and sulfur foul the exchanger, scale builds, and the discharge has its own permitting headaches. We install closed loops here, a sealed circuit of fused polyethylene pipe filled once with treated water and antifreeze. The well keeps doing what it does, and the loop never touches it.

The spec sheet for a Columbia County acre

A water-to-air unit with two stages or variable speed, sized to the cooling load, the larger of the two in this climate. A desuperheater, which uses waste heat from the compressor to heat domestic water for most of the year and is the one option almost everyone should take. Surge protection at the unit, because the indoor equipment is still electronic and the lightning does not care that the condenser is gone. And a maintenance plan, because a closed loop needs its pressure and antifreeze checked annually.

Loop days, equipment day, first bill

The loop field takes one to three days depending on trenching versus drilling and the weather; a June thunderstorm every afternoon slows a trench job. The indoor unit, pump kit and duct connections take a day, and the old outdoor unit leaves on our truck. We flush and purge the loop, pressure-test it, start the system and verify heating and cooling both. The first full bill from Clay Electric or Suwannee Valley Electric arrives a few weeks later, and that is when the decision proves itself. Cook’s will set the install up on a monthly payment schedule; no lender is named on this page because the terms change.