Buying a House With Geothermal in Oklahoma: What To Inspect Before You Close

I’m Dave Hartzell. I’ve spent 47 years in this trade, and geothermal is the system I get called about after a home inspector shrugs and writes “recommend HVAC contractor evaluate” on the report. A furnace or air conditioner sits where anybody can look at it. A geothermal loop is in the ground, out of sight, and it’s the single most expensive part of the system to get wrong. If you’re under contract on a house that already has geothermal, the loop is exactly what a walk through inspection cannot tell you anything about.

4.8 stars, 300+ Google reviews, and most of that reputation is built on the calls where I told a customer the truth instead of the easy answer. Buying a house with geothermal already installed is one of those calls.

Why a Normal Home Inspection Doesn’t Cover This

A general home inspector checks that the indoor unit runs, air comes out of the vents, and nothing looks obviously wrong. That’s reasonable on a gas furnace. It tells you almost nothing about geothermal, because the two things that determine whether that system serves the house well are buried: the ground loop and the water side of the heat pump. An inspector who isn’t geothermal trained has no way to test either one. I’m IGSHPA accredited, the credential built around ground loop design, installation, and diagnosis, so the loop and the water side are what I’m trained to test.

The Records To Demand From The Seller

Before you waive your inspection contingency, ask the seller, or their agent, for paperwork. Ask for:

• Loop type and depth. Vertical bore, horizontal trench, or pond loop, and how deep or how long. Drillers bill by bore feet, not pipe feet, so ask which one any number reflects. The loop is sized to the tonnage of the heat pump, and one undersized from day one struggles on the coldest and hottest days.
• Install date. Not “a few years ago.” An actual date, or an invoice or driller record with one on it.
• Model numbers. The heat pump, and the desuperheater if it has one. That tells a technician rated capacity, refrigerant, and whether parts are still made.
• Service history. Every invoice from every contractor who has touched the system, and whether it was maintained on a schedule or only called when broken.
• Driller license and plugging record. Oklahoma requires a licensed driller through the Oklahoma Water Resources Board to drill or plug a heat exchange well. If a loop was ever repaired or abandoned, there should be a record it was done to code.

A folder with dated invoices, a driller’s log, and model numbers you can look up is a good sign regardless of what those numbers turn out to be. It tells you somebody has been paying attention.

What a Bad Answer Sounds Like

I’ve sat across the table from enough sellers and buyers to know the answers that should slow you down. Listen for these:

• “It’s always worked fine, I’ve never had anyone look at it.” No service history on a system meant to run for decades isn’t reassuring.
• “I think it’s original to the house, not sure when that was.” Nobody knows the install date and there is no invoice or driller record to pin it down.
• “We had a well guy out here once for something, I don’t remember what.” No invoice or driller name means you can’t confirm the work was done and plugged to code.
• “It runs a little loud in the summer, but it’s fine.” Noise or struggling on the hottest days can point at a loop that isn’t moving enough heat, and loop problems are the expensive kind.
• “The last owner had some geothermal guy out here, don’t have his info.” No installer contact means nobody to call about design or warranty before you own it.

None of these answers mean walk away. They mean you need a technician on site before you close, not after.

What a Loop Pressure Test Actually Tells You

A closed loop system is a sealed circuit of water and antifreeze solution buried in the ground, and the heat pump only works as well as that loop holds its charge. When I run a pressure test, I’m checking whether the system holds steady over time or loses pressure. Steady pressure tells me the pipe, fittings, and header are sound. Dropping pressure tells me there’s a leak somewhere between the header and the field, a real problem to chase down on a buried system, and exactly the kind of finding you want on the table before you own the house, not after.

Pressure is only part of it. I also check entering and leaving water temperature, flow rate, refrigerant charge, and how the desuperheater is performing if the house has one. Together that tells me whether the loop was sized right for this house, whether the heat pump is pulling the performance it’s rated for, and whether anything on the water side needs attention before it turns into a failure during the first real cold snap or the first stretch of hundred degree days.

My $348 Flat Geothermal Diagnostic

I am IGSHPA accredited and a ClimateMaster GeoElite dealer, so on an inspection like this I can pull manufacturer data for the equipment in the house instead of just noting that it runs. That is the difference between a home inspector saying the unit powers on and somebody telling you what it will cost you after closing.

I charge $348 flat for a full geothermal diagnostic, any hour, weekday or after hours. That covers loop pressure, refrigerant charge, desuperheater, controls, and heat exchanger, and I give you a written report and a quote before I leave. There’s no credit or refund on that fee. For a buyer under contract, that written report is something you can put in front of your agent, your lender, or the seller, and it’s worth more than a verbal “sounds fine to me” from anybody walking the property.

I work geothermal statewide across Oklahoma. Kingfisher, Canadian, Oklahoma, Garfield, Major, Logan, and Blaine counties are my daily service area for routine calls, and that has never been the limit on geothermal. If the house you’re buying sits anywhere in Oklahoma, call me and I’ll come test it.

If the Diagnostic Finds a Problem

Sometimes the report comes back clean and you close with real confidence. Sometimes it doesn’t, and now you have real numbers to negotiate with, whether that’s a credit from the seller, a fix before closing, or simply knowing what you’re walking into. Repairs needed after you own the house can be financed through Synchrony, Wells Fargo, Wisetack, Klarna, or JB Financing, the same as any repair I do. Financing isn’t only for new installs, it covers repairs too.

A Word on the Tax Credit

If anyone tells you a new buyer can still claim a federal tax credit on a geothermal system already installed and running, that’s not accurate. The federal residential geothermal tax credit has expired. Don’t let a listing or an agent talk you into a number that isn’t real. Check current guidance at irs.gov or ENERGY STAR, and talk to a tax professional about your situation.

Call Before You Close, Not After

A geothermal system is the best heating and cooling investment a house can have when it was designed and installed right, and it’s an expensive surprise when it wasn’t. That difference is usually decided underground, years before you ever walked through the front door, which is why a pressure test before closing is worth more than any verbal reassurance from a seller. I’m a Master HVAC licensed, NATE certified, IGSHPA accredited technician, and this is the inspection I’d want done on a house before I signed for it myself.

Call 405-375-4822 to schedule a pre-closing geothermal diagnostic anywhere in Oklahoma.

Frequently Asked Questions

Do I really need a separate geothermal inspection if I already paid for a home inspection?

Yes. A general home inspector checks that the system runs, not what’s buried in the ground or the water side of the heat pump. Loop depth, loop type, and refrigerant charge are outside the scope of a standard home inspection.

What if the seller can’t find any of the loop records?

It happens, especially on older homes that have changed hands more than once. Missing paperwork isn’t a dealbreaker by itself, but it means I can’t verify loop type or depth from documents, so I need to test the system directly.

What does it cost to inspect a geothermal system before I buy the house?

My geothermal diagnostic is $348 flat. Replacement work is quoted separately before approval. You get a full written report on loop pressure, refrigerant charge, desuperheater performance, controls, and the heat exchanger.

Can a bad ground loop really be that expensive to fix?

A loop undersized for the house, or one with a slow leak in the buried piping, is one of the more expensive repairs in HVAC because the pipe is in the ground, not sitting in a garage. That’s why I test loop pressure before you close, not after.

Does the geothermal tax credit still apply if I buy a house that already has the system installed?

No. The federal residential geothermal tax credit has expired. Confirm current guidance at irs.gov or ENERGY STAR and talk to a tax professional about your situation.

Do you only work on geothermal in your regular service area?

My daily service area for routine calls is Kingfisher, Canadian, Oklahoma, Garfield, Major, Logan, and Blaine counties. Geothermal is different. I work it statewide across Oklahoma, so call me even if the house is outside those seven counties.