Geothermal Loop Upgrades in Oklahoma: When the Ground Is the Problem
I am Dave Hartzell. I own Hartzell’s Heat & Air in Kingfisher, I have been in this trade 47 years, and I am IGSHPA accredited for ground source work. This page is not for somebody shopping for a first geothermal system. It is for the person who already owns one and has quietly decided it was a mistake.
The bill crept back up, the backup heat runs more every January, and two techs have told you the equipment is fine. Nobody explained that the heat pump in your utility room and the pipe in your yard are two separate purchases, and only one of them is usually the problem.
How do I know it is the loop and not the heat pump?
- It got worse on a slope, not all at once. Compressors and boards fail suddenly. A field short on capacity gives you a good few years, then a little less every season.
- Backup heat runs more each winter for the same weather. Same house, same thermostat, more strip heat. That is the clearest signal I know of.
- It locks out in the worst week of the season, not randomly. A refrigerant fault does not care what time of year it is. A loop out of heat cares very much.
- You keep adding fluid. Pressure that will not hold, gurgling at the flow center, a circulator that sounds different. A slow leak shows up as noise long before a wet spot.
- You added square footage. A shop, a sunroom, a finished basement. The load went up. The pipe in the ground did not.
A ground loop is a bank account, not a fuel tank. Every winter you withdraw heat from the dirt, every summer you put it back. With enough pipe it recovers between seasons. Short, it does not, and next year starts colder than last. That drift is why it feels like the system is aging when it is not.
The good news: your heat pump probably stays
I can say that with some confidence because I am a ClimateMaster GeoElite dealer as well as IGSHPA accredited. I check the heat pump against the manufacturer’s own performance data before I ever recommend spending money in the yard.
A water source heat pump knows two things about your yard: how warm the water coming back is, and how fast it moves. ClimateMaster puts numbers on both in its commercial water source heat pump installation manuals: roughly three gallons per minute per ton, a floor of two once entering water temperature drops below 50 degrees, and a field adjustable low temperature cutout for antifreeze loops. Your own unit’s manual will have its version of those.
Hit those numbers and the machine does not care what shape the pipe is. Trench, bore or pond, all it ever sees is the water coming back to it. Loop geometry is nearly invisible to the equipment. Loop capacity is not.
| Usually stays | Usually gets touched |
|---|---|
| The heat pump itself | Flow center and circulators |
| Air handler and ductwork | Header piping and the wall entry |
| Desuperheater and water heater tie in | Purge, flush, antifreeze recharge |
| Thermostat and controls | Commissioning readings, before and after |
You need bigger equipment only if the load changed, meaning you built onto the house. Not because the loop changed shape.
From a slinky or horizontal field to vertical bores
A trench field lives in the top few feet of soil, the zone that dries out in an Oklahoma August and freezes shallow in January. Vertical bores reach ground that barely changes temperature all year, and they open up far less of your yard.
Pricing is where quotes stop being comparable. Figure roughly 200 bore feet per ton, and a loop field cost basis near $3,000 per ton. Drillers bill bore feet, the depth of the hole, not pipe feet. A bore with a U bend holds two legs of pipe, so pipe footage runs about double. A bid in pipe feet is not the same job as one in bore feet, and the cheap looking one may be half the field.
I do not own a drilling rig. I bring in a driller I trust and we work the job as a team.
Going to a pond loop, or adding one to what you have
If you have real water on the place, nobody has to drill. The ASHRAE design text these systems are sized from, Kavanaugh and Rafferty, puts the minimum useful pond depth near ten feet, with a ceiling around twenty tons per acre in cooling and ten in heating. A half acre pond at that ceiling covers a normal house, and heating is the limiting side.
Coil style matters. Slinky style is right for a heating dominant house, while tight compact coils are a cooling dominant design. A still pond stratifies, so water at the coil stays just above freezing even under surface ice, which is why it is anchored deep. A pond that runs warm in late August is a poor place to dump summer heat, so I want to see your water first.
You can also pair a pond loop with a vertical field you already own instead of replacing it. How the two share the load depends on what your existing field measures.
What the old field costs you to leave in the ground
A vertical bore is a regulated well in Oklahoma. Water Resources Board rules cover wells used for heat exchange, including heat pump wells, and both drilling and plugging them is licensed work. That license belongs to my driller, not to me. For plugging a dead vertical field, the state points at the IGSHPA industry standard instead of its own generic well rule, and my driller works to it. Retiring a field is licensed labor plus material, so it belongs on your estimate as its own line rather than buried in a total.
A shallow trench field is different. The written rules I can point to cover wells, and four feet of trench is not a well, so I check with the jurisdiction rather than assume. Often the better move is not retiring it at all: if the pipe still holds pressure, it can be tied in alongside the new field.
The cost people forget is the one they already pay. Every winter you run a short field, you buy that shortfall back in strip heat and compressor runtime.
Rebates, tax credits, and what I will not promise
The federal residential geothermal tax credit, section 25D, has expired. I am not going to soften that. Commercial buildings fall under section 48, not 48E, and that belongs in front of a tax professional rather than an HVAC contractor.
Oklahoma utility money is real and local. OMPA pays up to $800 per cooling ton on geothermal in municipal towns, including Kingfisher, Okeene and Watonga. That is a cap, not a guarantee, and it requires a desuperheater. Alfalfa Electric Cooperative pays $1,050 per ton for ground source against $150 for air source in Garfield and Major counties. Whether a loop only upgrade qualifies is a conversation with your utility, and I will not promise an amount before they do.
A loop upgrade can be financed. That is the whole sentence.
What it costs to have me look
My geothermal diagnostic is $348 flat, any hour, weekday or after hours. No credit and no refund, and I say so up front. You get a full performance audit: loop pressure, refrigerant charge, desuperheater, controls and heat exchanger, with a written report and a quote before I leave. If the answer is a new system, that estimate is free.
I work geothermal statewide across Oklahoma. 4.8 stars, 300+ Google reviews. Call 405-375-4822.
Questions I get asked about loop upgrades
Do I have to replace my heat pump too if I redo the loop?
Usually no. The heat pump cares about water temperature and flow, not the shape of the pipe outside. Equipment, ductwork, desuperheater and controls normally stay. New equipment is warranted only if the load on the house changed.
Can I add a pond loop to the vertical loop I already have?
Yes, that gets done. The two fields share the load, and the design question is how. I need to see how deep your water is and what your existing field measures under load.
What happens to my old loop field, do you dig it all up?
No. A dead vertical field is plugged in place, and in Oklahoma that is licensed work my driller handles, done to the IGSHPA standard the state points to. It will be a line on your estimate.
My other quote is in feet of pipe and yours is in bore feet. Which is right?
Both are legitimate units, they are just not the same number. A bore with a U bend holds two legs of pipe, so pipe footage runs about double. Ask every bidder to restate in bore feet.
Is there still a tax credit for a loop upgrade?
The federal residential credit, section 25D, has expired, so not that one. Oklahoma utility rebates are separate and worth checking.
Find out whether you bought the wrong system or just the wrong loop. Those carry very different price tags, and most of the money in your system is sitting indoors and still works. Call 405-375-4822 and I will tell you which one you have.