Geothermal That Makes Your Hot Water: Q-Mode and the Desuperheater
A desuperheater catches heat the system is already moving and hands it to your water heater. Q-Mode goes further and lets the machine run for the purpose of making hot water. And if your electric bill comes from your town rather than a co-op, the rebate requires a desuperheater or an integrated water heater to pay at all.
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I am Dave Hartzell, 47 years in this trade and IGSHPA accredited. I already have a page on what a desuperheater is and another on how one heats water in an Oklahoma house. This one goes a level deeper: the difference between recovering leftover heat and making hot water on purpose, and the rebate rule almost nobody hears in time to design around.
On a municipal utility, hot water is not an upgrade, it is the qualification
The Oklahoma Municipal Power Authority rebate requires the system to have at least one operating Integrated Water Heater or Desuperheater for domestic water heating. No desuperheater, no rebate. That is a condition of the program, not an upsell from me.
This is an expensive thing to find out late. Skip the hot water side to save a little on the install, and the rebate goes with it.
The geothermal category tops out at $800 per cooling ton, and that ceiling is not automatic. Each member town elects its own rebate level and the power authority matches it 50/50 up to the published amount, so what you actually get depends on your town’s elected level. Kingfisher, Okeene, Watonga and Edmond are member towns. If ton is a new word on you, start with what a ton of geothermal means.
- New installation or a conversion from another type of HVAC system. Not a like for like swap.
- An in home energy audit before installation, handled case by case. Here is my geothermal energy savings audit.
- Paperwork inside 90 days of installation. I handle it.
Three things this rebate is not. CKenergy Electric Cooperative pays $2,000 per ton up to $24,000, but it does not serve Kingfisher County, so it is not the one for a Kingfisher reader. OG&E residential rebates are closed for 2026. And I do not publish amounts for OEC, CVEC or KPWA, because I have not verified them and a stale number is how somebody ends up disappointed. Look at who sends your bill, then call me.
What a desuperheater is actually grabbing
Straight off the compressor, refrigerant vapor is hotter than the next step in the cycle needs. That extra is called superheat, and the system sheds it somewhere regardless. In cooling, somewhere means your ground loop.
A desuperheater is a small heat exchanger sitting on that hot line with a pump that moves water between it and your water heater. Water picks the superheat up on the way past and carries it to the tank. It is built double wall so a refrigerant leak cannot reach your drinking water.
None of that changes what the heat pump is doing for the house. The compressor was already running and the heat was already leaving. The desuperheater changes its destination from the dirt in your yard to the tank in your utility room.
Summer is when it pays, and I will say why plainly
In cooling season the whole job is getting heat out of your house and into the ground. That heat is a waste product. Sending some of it to the water heater instead costs the machine nothing it was not already spending, which is why summer hot water off a geothermal system is close to free.
Winter is a different story and I will not pretend otherwise. In heating season that heat was on its way into your house on purpose, so diverting it to the tank is not free any more, it is a trade. The desuperheater still contributes, it just stops being the bargain it is in July.
Q-Mode: hot water as the job, not the leftover
A desuperheater can only hand you what the compressor happens to be making. If the house is not calling for heating or cooling, the machine is off and there is no superheat to recover. On a mild Oklahoma week in April or October that can be most of the day.
Q-Mode is the difference between recovering hot water and producing it. The machine can run because hot water is what you need, not only because the thermostat asked for something. That turns hot water from a byproduct into something you can ask the system for, in any season. It is one of the reasons the Trilogy 45 sits where it does in the line, and my ClimateMaster page covers the rest of the range.
Storage is what makes opportunistic heat useful
Here is the part that gets skipped. When the hot water source is opportunistic, arriving whenever the machine happens to run, a normal sized tank is the wrong container. Heat shows up on the equipment’s schedule and gets used on your family’s schedule, and those two do not line up.
Storage is the buffer between them. A bigger tank lets the system bank heat all afternoon while the air conditioning runs and still have it there at six in the morning. On a real job I specified an 85 gallon tank for exactly that reason.
The right size is a design decision, not a catalog pick. It comes out of how many people live there, when they shower, and how the system is going to run. I size it as part of the proposal.
It supplements. It does not delete your water heater.
Your water heater stays. A desuperheater feeds it, it does not replace it, and the existing heater still covers a heavy draw or a mild shoulder week. Anyone telling you the geothermal system will handle all of your hot water is setting you up to be unhappy in October. Expectations get sized along with the tank, and I would rather tell you in advance which weeks feel almost free than let you find out and think something is broken.
And geothermal is a premium purchase. It costs more up front than a conventional system, hot water side included. It earns it back over years, not months, and I will show you that on your own house.
The federal residential credit is gone. Section 25D is expired: the IRS states it is not available for any property placed in service after December 31, 2025. I am not a tax professional, take your situation to yours, and do not build a budget around it. Utility rebates are where the money is in 2026.
Questions I get about geothermal hot water
Do I need a desuperheater to get the geothermal rebate in Kingfisher Oklahoma?
Yes. The municipal power authority program requires at least one operating Integrated Water Heater or Desuperheater doing domestic water heating. No desuperheater, no rebate, which is why I design it in from the start.
What is the difference between a desuperheater and Q-Mode?
A desuperheater recovers heat the machine is already producing, so it only works while the system is running for the house. Q-Mode lets the machine run because hot water itself is the job, in any season, so it is something you ask for rather than something you happen to get.
How much does a geothermal diagnostic cost in Kingfisher Oklahoma?
$348 flat, any hour, weekday or after hours. That includes checking the desuperheater circuit and the tank, with a written report and a quote before I leave. An estimate on a new geothermal system is free.
Bring me your electric bill and your shower schedule
The bill tells me which rebate program you are in. The rest tells me how big the tank needs to be. I confirm the level with your utility before I put a number on anything.
Geothermal is statewide work for me, not a seven county thing. I have run geothermal in Kingfisher, Okarche, Hennessey, Watonga, Dover, Loyal, Cashion, Crescent, Piedmont, Edmond, Yukon, Mustang, El Reno, Guthrie, Enid, Geary, Okeene, Fairview, Thomas, Ames and Oklahoma City, and as far out as Lawton, Broken Bow and Durant for a customer who wanted geothermal. There is one shop, in Kingfisher, and I drive. That is where I work, not a list of towns with a rebate.
Diagnostic on a geothermal system you already own is $348 flat, any hour. New system estimates are free. Master HVAC License · NATE Certified · IGSHPA Accredited · ClimateMaster GeoElite.