Why geothermal cooling costs half as much

Every June somebody asks me if geothermal is actually worth it. The brochure numbers from manufacturers are fine. The numbers that matter are what my real customers pay OG&E and CKenergy in July versus what their conventional neighbor with the same square footage pays. I have those numbers from Kingfisher, Canadian, and Garfield county installs. This episode lays out the actual July bills side by side, the upfront cost difference, the rebates that still apply in 2026, and when geothermal makes sense for a Central Oklahoma homeowner. More episodes: https://hartzellsheatair.com/podcast/

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Transcript

Two Identical Homes Two Bills

SPEAKER_01 0:00

So picture this. It is the first week of July. Um, specifically July 2026.

SPEAKER_03 0:06

Right, peak summer.

SPEAKER_01 0:07

Yeah. And in central Oklahoma, it has been baking at over a hundred degrees for eight days straight. Just miserable heat. And you have these two families living in identical 2,200 square foot houses built by the same builder, sitting literally directly across the street from each other.

SPEAKER_02 0:23

Basically the exact same variables, same family size, same Bemostat setting.

SPEAKER_01 0:28

Oh, exactly. But they open their power bills for the month, and one family owes $340, the other family owes $165.

SPEAKER_03 0:35

Half the price.

SPEAKER_01 0:36

Less than half. And today, our mission for this deep dive is to basically tear apart the blueprints of those two houses and figure out why that massive gap exists.

SPEAKER_03 0:46

Yeah.

SPEAKER_01 0:47

Because if you have ever opened a July power bill and just felt your jaw drop, this deep dive is absolutely for you.

SPEAKER_03 0:52

Oh, for sure. Because we generally just assume that if it's 105 degrees outside, well, you you are just going to have a massive power bill. We don't really question the mechanics of it.

SPEAKER_01 1:00

Right. We just accept the financial pain. But today, we are looking at this incredibly detailed set of records compiled by Dave Hartzall.

SPEAKER_03 1:08

Yeah, he is an HVAC master technician. He has like 45 years of experience out in Kingfisher, Oklahoma.

SPEAKER_01 1:14

Right. And we have his actual 2026 notes and side-by-side customer billing data. We are cutting through all the shiny marketing fluff to look at the brutal real-world math of home cooling. Because the only difference between those two identical houses is the actual machinery sitting in their backyards.

SPEAKER_03 1:32

Exactly. The house paying $165 has a geothermal heat pump, and the one paying double is using a standard conventional air conditioner.

SPEAKER_01 1:41

Okay, let's unpack this. Because looking at a $165 bill versus a $340 bill in the exact same weather, I mean, my immediate instinct is to ask how that is physically possible.

How Air Conditioners Really Move Heat

SPEAKER_03 1:52

Well, to get there, we kind of have to establish how a conventional air conditioner actually cools a house in the first place.

SPEAKER_01 1:57

I think most people, myself included, just assume an AC unit makes cold air, you know? Like how a furnace makes fire to make heat.

SPEAKER_03 2:05

Yeah, that is probably the most common misconception out there. And it's actually the root of why conventional systems struggle so much in extreme heat.

SPEAKER_01 2:12

So it doesn't make cold air.

SPEAKER_03 2:13

No, because cold isn't a physical thing you can create. It's just the absence of heat. So the only way to actually cool your living room is to physically capture the heat energy that's inside your house, carry it outside, and throw it into the yard.

SPEAKER_01 2:25

Wait, how do you carry heat? It's not like you can scoop it into a bucket.

SPEAKER_03 2:29

Right. So you use a chemical refrigerant. Think of the refrigerant in an air conditioner as like a thermal sponge. Okay, a sponge. Yeah. So inside your house, the system lets that refrigerant expand into a gas, and that allows it to soak up the heat from your indoor air, then it pumps that hot gas outside to the compressor.

SPEAKER_00 2:48

And the compressor is the big noisy box in the backyard.

SPEAKER_03 2:50

Exactly. And the compressor violently squeezes that gas, it condenses it back into a liquid, which basically forces all that absorbed heat to just radiate out into the outdoor air.

SPEAKER_01 3:01

Okay, so you are taking a sponge full of indoor heat, walking it outside and wringing it out. But in our Oklahoma scenario, the air outside is 105 degrees.

SPEAKER_03 3:12

And that right there is where the conventional system hits a thermodynamic wall because it's relatively easy to squeeze heat out of that sponge when the outdoor air is, say, a mild 80 degrees.

SPEAKER_00 3:23

Because the air is cool enough to take it.

SPEAKER_03 3:25

Right. But when it hits 105 degrees, the environment is already totally saturated with thermal energy. The outdoor air just does not want to absorb any more heat.

SPEAKER_01 3:34

So the compressor has to fight back.

SPEAKER_03 3:36

Exactly. To force that heat out into sweltering air, the compressor has to work incredibly hard. It pulls significantly more electrical amps to create the necessary pressure, and that just spins your electric meter faster and

Why SEER Ratings Mislead In Heat

SPEAKER_03 3:49

faster.

SPEAKER_01 3:49

That actually perfectly explains a detail in Hardcell's notes that really caught my eye. When you buy an AC unit, the brochure always has this sear rating in big bold letters.

SPEAKER_03 4:00

Right, the seasonal energy efficiency ratio. It is basically a measurement of how much heat the system can move per watt of electricity it eats.

SPEAKER_01 4:08

But the notes point out this massive catch. Those brochure sear ratings are tested in a laboratory at a super comfortable 82 degrees.

SPEAKER_03 4:16

Yeah, it's wild. Nobody is stressed about their power bill at 82 degrees.

SPEAKER_01 4:20

Exactly. But when the real world hits 105 degrees and the compressor starts fighting that atmospheric resistance, the actual efficiency of that conventional unit just plummets by like 25 to 35 percent.

SPEAKER_03 4:33

You are literally losing a third of your cooling capacity right when you need it the absolute most. Now contrast that with the geothermal

Geothermal Cooling Uses 65 Degree Soil

SPEAKER_03 4:40

system across the street. A geothermal heat pump is not fighting the outdoor air at all.

SPEAKER_01 4:44

Because it's not using the air.

SPEAKER_03 4:46

Right. Instead of trying to wring that thermal sponge out into a 105-degree oven, it pumps the heat into a liquid loop buried deep underground.

SPEAKER_01 4:54

And the dirt is cooler.

SPEAKER_03 4:56

Way cooler. In central Oklahoma, once you dig a few feet below the frost line, the soil stays at a remarkably stable 60 to 70 degrees all year round.

SPEAKER_01 5:04

So it sounds like a conventional AC is trying to push a huge boulder up a steep hill, you know, fighting against that 105 degree heat, while the geothermal system is just rolling that exact same boulder across a flat 65 degree plane.

SPEAKER_03 5:17

That is a perfect analogy. The temperature difference is finally working for you, not against you. And this is actually where we see terms in the source material like a four-ton system.

SPEAKER_01 5:26

Oh, right. I wanted to ask about that. What does the weight have to do with it?

SPEAKER_03 5:29

So it's a funny historical artifact. Before electrical refrigeration, people cooled buildings with actual blocks of ice. So a ton of cooling means the AC unit removes the exact same amount of heat from a house as it would take to melt a 2,000-pound block of solid ice over 24 hours.

SPEAKER_01 5:48

Oh wow. That is amazing. So a four-ton system is moving four literal tons of ice melting heat out of your house every single day.

SPEAKER_03 5:57

Exactly. And pumping that massive volume of heat into cool dirt just uses vastly less electricity than fighting the thick summer

Billing Data Beyond One Street

SPEAKER_03 6:04

air.

SPEAKER_01 6:04

Okay, but let me push back for a second here. Looking at just two houses across the street from each other, I mean, is this just a cherry-picked example? Maybe one family takes way longer showers or leaves all the lights on. What do the actual neighborhood averages look like?

SPEAKER_03 6:18

That's a fair question, but Hartzell's records back this up on a much wider scale. He pulled billing numbers from all across Canadian County.

SPEAKER_01 6:24

So looking at bigger data sets.

SPEAKER_03 6:26

Right. For instance, he tracked a 3,400 square foot home with a standard 14 SEER conventional AC. Their July bill was $410. But just two miles down the road, a comparable 3,300 square foot home running a horizontal loop geothermal system paid only $215 for the exact same month.

SPEAKER_01 6:45

Wow. Okay, so the pattern holds up.

SPEAKER_03 6:48

It is rock solid. Across different counties and system sizes, geothermal customers are consistently paying roughly 45 to 55% of what conventional customers pay in the peak summer heat.

SPEAKER_01 6:59

Okay, so the summer mechanics make total sense

Winter Heat Pumps And Heat Strips

SPEAKER_01 7:01

to me. If the ground is 65 degrees, it is obviously way easier to dump heat into it. But that spable 65 degree birth introduces a really obvious flaw when we move to the winter months.

SPEAKER_03 7:11

Oh, I see where you're going.

SPEAKER_01 7:12

Yeah, because in January, I want my living room to be 70 degrees. But 65 degree dirt is colder than my living room. How does colder dirt possibly help me heat my house?

SPEAKER_03 7:21

So to understand the winter cycle, we have to take that thermal sponge analogy and run it completely in reverse. A heat pump in the winter takes that chemical refrigerant, moves it outside, soaks up thermal energy from the environment, brings it inside, and then releases that heat into your house.

SPEAKER_01 7:38

Wait, hang on. For a conventional heat pump, it's pulling heat from the outside air. Right. But if it is 25 degrees outside in January, there is no heat out there to soak up. It is literally freezing.

SPEAKER_03 7:50

And that is the incredibly counterintuitive nature of thermodynamics. Even at 25 degrees, the air still holds thermal energy.

SPEAKER_00 7:57

Seriously.

SPEAKER_03 7:57

Yeah, because absolute zero is minus 460 degrees Fahrenheit. Anything warmer than that technically possesses some heat. The real magic is the refrigerant itself. These chemicals have incredibly low boiling points. Some of them literally boil at minus 50 degrees Fahrenheit.

SPEAKER_01 8:14

So you're saying even 25 degree winter air is hot enough to physically boil the refrigerant inside the pipes.

SPEAKER_03 8:20

Exactly. And when a liquid boils into a vapor, it absorbs heat energy. Then the system pumps that slightly warmed vapor inside, the compressor violently squeezes it to concentrate the heat, and boom, that warms your house.

SPEAKER_01 8:33

That is an incredibly elegant piece of physics. But um Herzl's notes indicate that this elegant physics basically falls off a cliff when the temperature drops too low outside.

SPEAKER_03 8:44

It totally does because it's an issue of heat density. Once the outside air drops below 25 degrees, there is just less and less thermal energy available for that refrigerant to soak up.

SPEAKER_01 8:54

So the sponge is coming back mostly dry.

SPEAKER_03 8:56

Right. So the compressor has to run constantly, just moving massive volumes of this low heat vapor, desperately trying to scrape together enough thermal energy. And eventually it reaches a point where it just can't extract heat fast enough to replace what your house is losing through the windows and walls.

SPEAKER_01 9:12

And that is when the conventional system basically hits the panic button. Wait, the notes describe this when the heat pump can't keep up, it defaults to these electric heat strips.

SPEAKER_03 9:21

Yep, the emergency backup heat.

SPEAKER_01 9:22

And Hartzell essentially describes these as a giant toaster hidden inside your air handler.

SPEAKER_03 9:29

Mechanically speaking, that is exactly what they are. They are just large high voltage coils of wire. The system blasts a massive amount of electrical current through them. The wires resist the flow and they glow red hot, generating raw heat.

SPEAKER_01 9:44

I mean, it is kind of insane that we have this modern era of high-tech thermodynamics, right? Phase-changing refrigerants and all that. And our ultimate backup plan for a freezing night is to plug in a giant electric toaster to heat a whole house.

SPEAKER_03 9:57

It's an incredibly brute force method. Creating heat through electrical resistance is quite literally the most energy-intensive way to warm a space. The data and the notes show that these resistance droops use three to five times the electrical power of the heat pump itself.

SPEAKER_01 10:12

So when those turn on, your meter just goes into overdrive.

SPEAKER_03 10:14

Exactly. But what's fascinating here is how the geothermal system handles that exact same winter night. Because while the conventional pump is desperately trying to boil refrigerant using freezing 15-degree air, the geothermal system is still just running its loops through 65 degree dirt. Oh, so it's swimming in thermal energy.

SPEAKER_01 10:32

Exactly. Even in a blizzard, it never struggles to find heat because that 65 degree soil provides a massive, constant surplus.

SPEAKER_03 10:40

Which means it never falls behind. So it never has to trigger a giant electric toaster in your ductwork.

SPEAKER_01 10:46

Never. It just operates entirely on that highly efficient refrigeration cycle. And as a result, the January billing data shows geothermal users routinely paying 40 to 60% less than comparable all electric conventional homes.

SPEAKER_03 11:01

Okay, so the physics are vastly superior. You are having your summer bills, you're entirely avoiding the toaster in the winter.

Upfront Cost And The Tax Credit Trap

SPEAKER_03 11:07

But if it's this good, why doesn't every single house have one?

SPEAKER_01 11:10

Well, yeah, there's always a catch.

SPEAKER_03 11:12

Right. We have to look at the immediate barrier to entry here, the upfront cost in the year 2026. Because I want to lay the bare numbers out without sugarcoating them.

SPEAKER_01 11:21

Oh, the sticker shock is substantial. An installed residential geothermal system for a typical home right now runs anywhere between $22,000 and $32,000. $30,000 is a huge capital investment for the average person. And the expert notes have a highly specific, timely warning from Hartzell about that sticker price that we really need to emphasize.

SPEAKER_03 11:42

Yes. The federal section 25D geothermal tax credit completely expired on December 31st, 2025.

SPEAKER_01 11:49

So it's gone.

SPEAKER_03 11:50

It's totally gone. So if you have a contractor sitting at your kitchen table in 2026 and they promise you a massive federal tax credit to offset a $32,000 install, you need to walk away immediately. They are either using outdated information or intentionally misleading you.

SPEAKER_01 12:06

So what does this all mean for my wallet today? If the federal credit is gone, is this tech suddenly just unaffordable? Because paying 30 grand out of pocket to save, you know, a hundred bucks a month, that takes decades to break even.

SPEAKER_03 12:18

Aaron Powell It would if you had to pay the full sticker price. But there is a lifeline

Utility Rebates And Grid Peak Demand

SPEAKER_03 12:22

here. The slack left by the federal government is actually being aggressively picked up by local utility companies.

SPEAKER_01 12:27

Wait, really? The utility companies are giving rebates. Why would a power company hand me thousands of dollars to help me buy less of the electricity they are trying to sell?

SPEAKER_03 12:36

It sounds totally backwards, right? But it comes down to the incredibly fragile nature of the electrical grid. Electricity isn't like municipal water. You can't just generate a bunch of it at night and store it in a giant tank for tomorrow.

SPEAKER_01 12:48

Right. It has to be generated the exact millisecond it's used.

SPEAKER_03 12:51

Exactly. And in the middle of an Oklahoma July, when tens of thousands of conventional AC units are all simultaneously fighting that 105 degree air, the power grid hits its absolute maximum capacity.

SPEAKER_01 13:05

Right, pushing us toward rolling blackouts.

SPEAKER_03 13:07

Yep. And to prevent those blackouts, utility companies are forced to build these things called peaker plants. These are massive power generation facilities that literally sit completely idle for 11 months of the year and they only turn on during peak summer demand.

SPEAKER_00 13:22

That sounds incredibly expensive.

SPEAKER_03 13:23

Outrageously expensive to build and maintain. So for a power company, just handing a homeowner an $8,000 rebate to permanently lower their peak summer demand is vastly cheaper than spending hundreds of millions building a new peaker plant just for a few weeks in July.

SPEAKER_01 13:38

The economics of the grid are just wild. So what did these local Oklahoma rebates actually look like on paper?

SPEAKER_03 13:45

Yeah, so looking at the specifics, CK pays $2,000 per ton of cooling capacity. Though note that isn't available in Kingfisher County specifically. But for a standard four-ton home elsewhere on their grid, that is an $8,000 check taking the edge off.

SPEAKER_01 14:02

Nice.

SPEAKER_03 14:02

And OGE pays $1,000 per ton plus a flat $1,500 per unit. So that takes $5,500 off a four-ton system.

SPEAKER_01 14:11

Okay, let's crunch the final numbers together on this. Say we have a net OGE geothermal install, and after rebates, it lands at roughly $22,500. Okay. Meanwhile, a high-end $18 C or conventional system costs around $12,000. So you are paying a $10,500 premium up front to go with geothermal.

SPEAKER_03 14:30

Right. That's your initial hurdle. But we know from Hart Cell's billing data that you are saving roughly $970 to $1,100 every single year in energy costs.

SPEAKER_01 14:37

So it pays for that premium in basically nine to ten years.

SPEAKER_03 14:40

Exactly. By year 10, the upgrade has entirely paid for itself, and everything after that is pure savings in your pocket.

SPEAKER_01 14:45

Aaron Powell Okay, so the financial math works out over a decade. But what happens after year 10? I mean, what if the system catastrophically breaks down in year 11 and wipes out all those savings?

Payback Timeline Lifespan And Maintenance

SPEAKER_03 14:56

Well, when you evaluate that, you have to look at the lifespan asymmetry between the two systems. Because comparing conventional to geothermal is definitely not an apples to apples comparison of assets. Oh so think about a conventional outdoor condenser. It sits in your backyard, it gets baked by UV radiation, it gets pelted by hail storms, it gets choked by dust. Yeah. It generally only lasts 12 to 15 years.

SPEAKER_01 15:19

Which brings up a really funny detail from Hart Cell's Notes. He talks about maintenance and specifically mentions the contactors failing because of ants. What is a contactor?

SPEAKER_03 15:28

So a contactor is basically a heavy-duty magnetic switch. When your thermostat calls for cold air, it sends a low voltage signal outside, and this heavy magnetic switch slams shut to let the high voltage power flow into the compressor.

SPEAKER_01 15:41

Okay, like an ignition switch.

SPEAKER_03 15:42

Right. But every time that switch slams shut, it creates a microscopic electrical arc. And for some wild reason, certain species of ants are highly attracted to the ozone created by that arsing.

SPEAKER_01 15:54

Oh no.

SPEAKER_03 15:55

Oh yeah. They swarm the switch, they get electrocuted, their bodies pile up between the magnetic plates, and eventually the switch just can't close anymore. The entire AC unit dies because of a pile of dead bugs.

SPEAKER_01 16:08

Or because the equipment is forced to live outside in nature. But maintenance costs overall are pretty similar, right?

SPEAKER_03 16:13

Yeah. A basic maintenance plan for either system with Heart Cells Company runs about $360 a year. But with a conventional plan, you are constantly fighting to keep failing outdoor equipment alive. Whereas a geothermal compressor lives safely indoor.

SPEAKER_01 16:27

Like in a basement or garage.

SPEAKER_03 16:29

Exactly. Safe from the sun, safe from hail, safe from ants. And because of that, the indoor compressor usually lasts 20 to 25 years.

SPEAKER_01 16:36

Wow. And the underground loop itself, the buried pipes, those have a documented lifespan of over 50 years.

SPEAKER_03 16:42

Yeah, it's essentially a half-century asset.

SPEAKER_01 16:44

Okay, here's where it gets really interesting.

Installation Disruption And Contractor Skill

SPEAKER_01 16:46

Because if I am listening to this, I am sold on the 50-year lifespan. The math makes sense. But what is the actual physical nightmare of getting this piping into my house? Let's talk about the honest downsides.

SPEAKER_03 16:59

Right, because the shiny brochure has definitely buried this part in the fine print. You have to move dirt and you have to move a massive amount of it.

SPEAKER_01 17:06

Walk me through it.

SPEAKER_03 17:07

Basically, you have two choices. If you have a small lot, you need a massive heavy-duty drilling rig worked on your property for a couple of days to drill vertical wells hundreds of feet straight down.

SPEAKER_01 17:18

That sounds intense.

SPEAKER_03 17:19

It is. Now, if you have the acreage, you can do horizontal trenching, but you have to completely tear up roughly half an acre of your yard with excavators, mountains of topsoil, deep trenches. It you basically have to completely replant your property afterward.

SPEAKER_01 17:35

So your yard is an active, heavy construction site for a week. And the notes also mention an issue with older homes specifically.

SPEAKER_03 17:42

Oh, the ductwork, yeah. If your older home has leaky, uninsulated ductwork, you have to fix that first. Otherwise, you are just pumping brilliantly conditioned, cheap air straight into your attic. You are wasting all the efficiency you just paid for.

SPEAKER_01 17:56

Okay. One more hurdle from the source material. Heart cells stresses that you cannot just hire anybody to do this. You need an IGSHPA accredited professional.

SPEAKER_03 18:07

Yes, the International Ground Source Heat Pump Association.

SPEAKER_01 18:10

Why is that so vital? I mean, why can't a regular AC guy just dig a trench and lay some pipe?

SPEAKER_03 18:16

Because burying that pipe requires an engineer's understanding of ground thermodynamics. If a contractor just digs a narrow trench and packs the pipes way too close together, you run the risk of thermal saturation.

SPEAKER_01 18:28

Thermal saturation. What happens then?

SPEAKER_03 18:29

Well, during a scorching July, you are constantly pumping heat into the soil around those pipes. If the soil can't absorb the heat fast enough, the dirt temperature rises from 65 to 75 to 85.

SPEAKER_01 18:40

Oh, so you create a pocket of hot dirt.

SPEAKER_03 18:42

Exactly. Suddenly your system is trying to dump heat into 90 degree soil, it loses all its efficiency because you literally cooked your own yard.

SPEAKER_01 18:50

Wow. The system basically chokes on its own exhaust. So you really do need a professional, not just someone who took a weekend seminar.

The Real Trade Off And Takeaway

SPEAKER_03 18:57

Exactly.

SPEAKER_01 18:57

So bringing this all back to you, the listener, what we are looking at is a profound trade-off. Geothermal is an upfront investment. It requires dealing with a major construction project that will absolutely tear up your lawn, and you have to meticulously verify your installer's credentials.

SPEAKER_03 19:13

It's not a weekend swap out project.

SPEAKER_01 19:16

Not at all. But in exchange, it fundamentally insulates you from the extreme weather of both July and January. By tapping into that stable dirt, you cut your cooling costs in half, you slash your heating costs, and you double the lifespan of your equipment. And even without the federal credit in 2026, those local utility rebates make the 10-year payback a total reality.

SPEAKER_03 19:39

You know, it really requires a mental shift. We spend so much time and energy worrying about how to aggressively insulate our homes from the harsh air surrounding them. But what if the ultimate solution isn't about fighting the atmosphere at all? What if the answer is finally teaming up with the stable, quiet earth right beneath our feet? The ground you walk on every single day might just be the most powerful energy asset you own. You just have to be willing to dig for it.