A dual fuel system pairs an electric heat pump with a gas furnace and switches between them automatically based on outdoor temperature. In Fredericksburg and across the Texas Hill Country it is one of the better-matched configurations available, because our climate plays to both halves.

How the Switching Works

The system has a balance point — an outdoor temperature below which the gas furnace becomes the more economical or more capable choice.

Above it, the heat pump handles heating. Because it moves heat rather than generating it, it delivers substantially more heating energy than the electricity it consumes.

Below it, the controls shut the heat pump down and bring the furnace on. The changeover is automatic and you generally will not notice it happening.

That balance point is set during commissioning using your equipment, local utility rates, and the relative cost of gas versus electricity. It is not a factory default, and setting it correctly is a meaningful part of what makes the system worth having.

Why Our Climate Suits It

Hill Country winters are short and mostly mild, which means the heat pump handles the overwhelming majority of heating hours at high efficiency.

The genuinely cold stretches — the hard freezes that arrive every few winters — are exactly when a gas furnace earns its place. Heat pumps lose capacity as temperatures drop, and having a furnace behind them removes any question about performance during a freeze.

Meanwhile our cooling season runs roughly seven months, so the heat pump’s compressor is working most of the year regardless. Adding efficient heating to equipment you were buying anyway is good use of the investment.

Lower Operating Costs Through Most of the Year

The savings come from running the efficient equipment during the hours it is efficient, rather than committing to one fuel year-round.

An all-gas system burns fuel every heating hour, including mild days when a heat pump would have done the job for less. An all-electric system with resistance backup burns expensive electricity during cold snaps.

Dual fuel takes the better option at each temperature automatically.

Comfort and Reliability

Heat pump air is warm rather than hot — noticeably cooler than furnace air, even though the room reaches the same temperature. Some people find that takes adjustment.

With dual fuel, the furnace is there for the coldest days, so you get familiar furnace heat when it matters most while running the efficient equipment the rest of the time.

There is also a resilience argument. Having two heating sources in a region where both the grid and the weather have been tested is worth something.

Who Benefits Most

The clearest case is a homeowner replacing an aging air conditioner who already has a serviceable gas furnace. Choosing a heat pump instead of a straight air conditioner adds efficient heating for a modest premium, and the existing furnace becomes the backup.

It also suits households replacing both systems at once who want efficiency without giving up furnace-grade heat during a freeze.

Where It Does Not Fit

Homes without gas service — there a straight heat pump with electric backup is the configuration.

Homes where the existing furnace and air conditioner both have years of life left. There is no reason to change anything.

And homes where the added control complexity is not justified by the heating hours involved. We will tell you if that is your situation.

Getting the Configuration Right

The thermostat has to support dual fuel specifically, and it has to be configured for your equipment and rates. Set incorrectly, the system either runs the furnace when the heat pump could have handled the load or leans on the heat pump past the point where it is economical — and neither produces a visible symptom.

Ductwork matters too, since heat pumps generally move more air than the equipment they replace. We measure static pressure before quoting, and sometimes duct sealing delivers more than the equipment upgrade.

Details are on our hybrid fuel systems page. Financing is available.

Contact 72 Degrees or call (830) 240-1835.