The dual-fuel idea in one paragraph
Every heat source has a cost per BTU delivered — how many pennies of energy it takes to deliver 100,000 BTUs into your home. That cost depends on the fuel (electricity or natural gas), the equipment efficiency at the current operating conditions, and your utility rates. A heat pump's cost per BTU is low at moderate winter temperatures and climbs steeply as it gets colder (efficiency drops with outdoor temperature). A gas furnace's cost per BTU stays roughly flat across all outdoor temperatures. Plot the two lines. They cross at some outdoor temperature. That crossing point is your economic balance point — the outdoor temperature at which gas becomes cheaper than heat pump.
A dual-fuel system knows this and picks the cheaper source hour by hour. Above the balance point, it runs the heat pump. Below, it fires the furnace. In an Oklahoma winter, that means the heat pump handles maybe 85-92% of the heating hours (the mild days from October through late-February) and the furnace covers the deep-cold minority (the 10°F snaps, the ice storm mornings). You pay less for heat on average than either source alone would provide.
The catch: you're buying both pieces of equipment. Whether the operating-cost savings pay back the higher install cost depends on your home, your rates, and how long you plan to stay. Here's the honest framework.
How dual-fuel compares to the other Oklahoma winter options
| All-electric heat pump | Dual-fuel (HP + gas furnace) | Straight gas furnace + AC | |
| Heat above ~30°F | Heat pump alone | Heat pump alone | Gas furnace |
| Heat below ~30°F | Heat pump + electric strip backup | Heat pump defers to gas furnace | Gas furnace |
| Summer cooling | Heat pump (same equipment) | Heat pump (same equipment) | Central AC (separate equipment) |
| Deep-cold reliability | Good with modern CCHP; strip heat is thirsty | Excellent — gas furnace always ready | Excellent |
| Cost per BTU when it's 40°F outside | Low | Low (HP running) | Higher (gas at any temp) |
| Cost per BTU when it's 15°F outside | Higher (strip heat) | Lower (gas taking over) | Moderate |
| Total install cost | Baseline heat-pump price | Heat-pump price + gas furnace + communicating thermostat | Furnace + separate AC |
| Requires existing ONG gas service? | No | Yes (or willing to add hookup) | Yes |
When dual-fuel is the right answer
1. You already have functional ONG gas service
If your home has a gas line and either (a) an existing gas furnace at end-of-life, or (b) a gas water heater or cooktop meaning the meter and line are already sized, dual-fuel adds relatively little incremental cost on the gas side. If your home is all-electric and would require new gas service to be run, that adds significant cost and time to the dual-fuel equation and usually tips the decision toward all-electric heat pump instead.
2. The home has a higher-than-average heating load
Older, larger, or less-insulated homes have higher heat-loss rates, which pushes the effective balance point up and puts more of the winter hours in the "below balance point" zone. When that's a meaningful portion of the winter, the operating-cost savings of dual-fuel become significant enough to justify the install premium.
3. You want ice-storm reliability
Oklahoma gets ice storms. When the grid goes down and temperatures are in the teens, a heat pump paired only with electric strip backup can't provide much heat on a generator. A gas furnace can — it runs on a small amount of electricity (blower and control power, easily generator-supported) and heat from the gas line, which doesn't fail during grid outages. For homeowners who prioritize deep-cold reliability, dual-fuel provides an extra layer that all-electric doesn't.
4. You plan to stay in the home 10+ years
The dual-fuel install premium is paid back through operating-cost savings over years. The math works better the longer you stay. For homeowners who might move within 3-5 years, the payback often doesn't complete before the sale — and future buyers usually don't pay a premium for dual-fuel over a simpler system.
5. Natural gas rates in your area are competitive with electricity
In Stillwater and most of central Oklahoma, ONG gas rates are historically competitive with OG&E electric rates on a per-BTU basis. Dual-fuel math works well here. In markets with higher relative gas rates (some parts of the country), all-electric heat pump often wins outright regardless of climate. Local rate context matters.
When all-electric heat pump is the better answer
- The home is all-electric today and adding gas service would be expensive or logistically difficult.
- The heating load is modest — tight modern construction with good insulation where the balance point sits low (20°F or below) and backup heat rarely runs.
- You want the simplest system possible — one outdoor unit, one indoor unit, one fuel source, one warranty. Some homeowners strongly prefer this.
- You'd prefer to run the home on future solar or on-site renewables — dual-fuel locks in a fossil-fuel component that limits future electrification.
- You're on a very tight install budget and the dual-fuel premium pushes the project outside what you can commit to.
The Oklahoma operating-cost math (a real example)
For an illustrative Stillwater home — 1,800 sq. ft., moderate insulation, cold-climate inverter heat pump on the heat side, current OG&E and ONG rates:
- All-electric heat pump: ~85% of winter hours on heat pump alone, ~15% on electric-resistance backup. Annual heating operating cost: baseline reference number.
- Dual-fuel (same HP + gas furnace backup): same ~85% of winter hours on heat pump; the remaining 15% now on gas furnace instead of strip heat. Annual heating operating cost typically 15-25% below the all-electric case in this example.
Over 15 years of ownership, the operating-cost savings from dual-fuel commonly pay back the install premium — but the payback horizon varies widely with rate assumptions, home characteristics, and the specific equipment installed. There is no substitute for running the numbers on YOUR house with YOUR utility bills. Sitton includes that on every dual-fuel quote.
"Dual-fuel is the right answer for maybe 40% of the Stillwater homes I look at. All-electric heat pump is right for another 40%. Straight gas furnace + AC is right for the other 20%. The way we get to the right answer is Manual J + real utility rates + the family's plans for how long they'll be in the house. What I refuse to do is guess. Everyone who's sold you HVAC 'guessing' has been reading from a script." — Bryan Sitton, Owner, Sitton Mechanical (EPA 608 Certified, Authorized Daikin Dealer)
How dual-fuel gets installed wrong (avoid these)
- Crossover temperature set to a factory default that ignores your rates. Many installers leave the crossover at whatever the thermostat shipped with (often 35°F or 40°F). Your actual economic balance point might be 28°F or 45°F. Wrong crossover means the wrong source is running for hours every winter. Sitton commissions this with your utility-rate data at install.
- Undersized furnace on the backup side. If the gas furnace is sized only to cover the deep-cold minority of hours, it may be undersized for a genuine ice-storm event. Right-sizing the gas furnace to actually cover the whole heat load (not just the "help me out below balance point" role) provides real emergency reliability.
- Communicating vs. conventional thermostat mismatch. Dual-fuel works best on a communicating thermostat that knows both pieces of equipment and can talk to the outdoor unit's compressor-staging feedback. A conventional 24V thermostat can still run dual-fuel but is dumber about the crossover decision. Ask which is being installed.
- Missing the annual crossover recheck. Utility rates change year to year — sometimes meaningfully. Sitton rechecks the crossover setting on every fall tune-up so it stays tuned to current rates.
What Sitton does on a dual-fuel install
- Manual J load calc on the home so we know the true heat load at Stillwater's 8°F design temperature. Deep dive here.
- Utility rate analysis on your last 12 months of OG&E and ONG bills to calculate the real economic balance point.
- Equipment selection — cold-climate heat pump matched to the load, gas furnace sized to cover full load as backup, communicating thermostat that manages the crossover intelligently.
- Manual D duct verification — confirm the duct system handles both equipment airflows correctly (heat pump and furnace often have different CFM optimum).
- Commissioning with rate-based crossover — we set the crossover temperature based on the utility-rate math, not a factory default.
- Documented operating-cost projection — you leave with a year-1 through year-15 cost model that shows what you're actually buying.
Your next step
If you're weighing dual-fuel against all-electric or against straight gas for a Stillwater home, call (405) 780-3034 or request a no-pressure in-home evaluation. We'll run the Manual J, model the operating-cost math with your actual utility bills, and email you the comparison report whether or not you choose Sitton. Read the companion pieces: the heat pump vs. furnace 2026 framework for the higher-level comparison and the balance point explainer for the underlying math on why crossover temperature matters so much.