What Is the Payback Period on Geothermal?

I am Dave Hartzell, 47 years in HVAC and 15+ years running Hartzell’s Heat & Air out of Kingfisher. Here is the answer nobody leads with: there is no single payback number, and anybody who quotes you one before seeing your house and your usage is making it up.

Every contractor site prints a tidy range with nothing behind it. I would rather show you what actually moves the number, so you can reason about your own house.

What you are replacing is the single biggest driver

This one dwarfs everything else, and it is decided before I ever quote you.

• Propane pays back fastest, by a wide margin. If you heat with propane, you are buying delivered fuel at whatever the market says this winter. That is where geothermal makes its strongest case in Oklahoma. Details on geothermal versus propane.
• Electric resistance is also fast. Strip heat, baseboard, an old furnace on emergency heat half the winter. You are paying full price for every unit of heat, with no multiplier working for you.
• An efficient natural gas furnace is the slowest. A lot of contractors will not say that out loud. On a good gas furnace at a reasonable rate, the gap geothermal has to close is narrower, so the number gets longer. That is not a knock on the system, it is arithmetic you deserve before you sign.

What you pay per unit of energy, and which direction it moves

Payback is a race between what you save each year and what you paid up front. The savings side is your fuel cost against your electricity cost.

Fuel prices move. Ground temperature does not. Propane can jump between one winter and the next. The dirt under your yard sits where it sat last year, which is why geothermal efficiency does not collapse on the coldest morning or the hottest afternoon the way an outdoor unit does.

The mechanism is the coefficient of performance: a geothermal heat pump moves heat instead of making it, delivering about $4.50 of heat for every $1 of electricity. Across a year that is roughly 50% less energy used for heating and cooling. That is energy use, not your total bill. More on what geothermal does to my electric bill.

Your utility, which changes the number by thousands

Oklahoma has three worlds here, and your address decides which one you are in.

• Municipal towns on OMPA, including Kingfisher, Okeene and Watonga. That program pays up to $800 per cooling ton on a qualifying new geothermal install. Read “up to” literally: $800 is a cap, each town elects its own level, and OMPA matches 50/50. One condition quietly disqualifies people: the system needs a working desuperheater or integrated water heater for domestic hot water, which is a design decision made before the quote, not an upsell after. I confirm your town’s current level before it goes into any number I hand you.
• Co-op territory. CKenergy pays $2,000 per ton, up to $24,000 on new installs, the strongest geothermal rebate I work with. It does not cover Kingfisher County, which surprises people here every time. Full picture on the CKenergy geothermal rebate page. Other co-ops including OEC, CVEC and Cimarron set their own levels, and I check yours.
• Investor-owned. OG&E residential rebates are closed for 2026. If somebody built you a proposal that counts on one, the proposal is wrong.

The federal residential credit expired, and most people do not know it yet

The federal residential clean energy credit, Section 25D, is gone. The IRS states it is not available for any property placed in service after December 31, 2025. Paying in 2025 does not preserve it if the system was installed in 2026.

That lengthened payback for every residential geothermal buyer in the country, and plenty of homeowners are still holding a half-remembered “there is a 30% credit,” waiting on something that is not coming back. Check current IRS and ENERGY STAR guidance and your own tax professional, because I am an HVAC contractor and not your accountant. Practically: your utility rebate is now the live lever.

How long you plan to own the house

Payback assumes you are still there to collect it. If this is the house you intend to stay in, that matters more than any efficiency rating on the sheet. If you might move soon, be honest about it.

On resale: geothermal is a genuine selling feature and buyers who understand it pay attention. I am not going to tell you what it adds at appraisal, because I do not know and neither does anybody quoting you a figure. Appraisers often have no comparable pair in rural Oklahoma. It is a real benefit you cannot bank a number on.

If there is already a loop in the ground

This changes everything. The loop is the expensive half of a geothermal system, and it is the half that stays. If you bought a house with a working loop, or you are replacing equipment on a loop I can verify, you are pricing a much smaller job and no generic payback chart applies.

Two cautions. I verify the loop before anybody counts on it: pressure, flow, and refill history. And a like-for-like replacement is often a different rebate tier than a new install, so do not assume the headline number above applies to you.

Whether the system is sized right

An oversized system never earns the model somebody built for it. It satisfies the thermostat, shuts off, fires again, and spends its life short cycling instead of running at the steady output where a heat pump is efficient. The savings in the proposal never show up, and the payback slides past whatever year was on the sales sheet. Sizing is the assumption the model rests on.

The honest close

Geothermal is a premium purchase. It costs more up front than conventional equipment. It is supposed to, and it earns that back through what it does not spend every month. Anybody selling it as the cheap option is setting you up to be disappointed.

The only way to a real number for your house is to sit down with your own 12 months of usage, your fuel, your utility and your ductwork, and work it out. That analysis is free. Start at the geothermal energy savings audit. To see how the return side gets modeled, that is on geothermal ROI in Oklahoma. Sitting on cash and wondering whether to use it? Read should I finance geothermal if I have cash.

Geothermal is the one thing I go statewide for. I have run jobs out of Kingfisher, Okarche, Hennessey, Watonga, Dover and Cashion, through Piedmont, Yukon, El Reno, Guthrie, Enid and Oklahoma City, and as far out as Lawton, Broken Bow and Durant. One shop, here in Kingfisher, and I drive to you.

Questions I get about geothermal payback

What is the payback period on geothermal in Oklahoma?

There is no single number, and I will not invent one. It is driven by what you are replacing, what you pay for that fuel, what your utility rebates, how long you will own the house, whether a usable loop is already in the ground, and whether the system is sized right. The honest number comes from your own 12 months of usage.

Is geothermal still worth it now that the federal tax credit expired?

The federal residential credit under Section 25D is not available for property placed in service after December 31, 2025, and that lengthened payback for everybody. Your utility rebate is now the lever that moves the number, and in strong co-op territory it moves it by thousands. Check current IRS and ENERGY STAR guidance and your own tax professional.

Does geothermal pay for itself faster if I heat with propane in Oklahoma?

Yes, and it is not close. Propane is the fastest payback of any fuel I replace, because you are buying delivered fuel at whatever the market charges that winter. Electric resistance is next fastest, an efficient natural gas furnace slowest.

How much does a geothermal estimate cost in Kingfisher Oklahoma?

An estimate on a new system is free, including the usage analysis that produces your actual numbers. A diagnostic on a geothermal system you already own is different: $348 flat, any hour, weekday or after hours, with a written report and a quote before I leave.