How a Heat Pump Actually Heats
A heat pump doesn't generate heat the way a furnace does. Instead, it moves heat from one place to another, pulling warmth from the outside air and transferring it indoors in winter, then reversing the process in summer to cool your home. This sounds counterintuitive when it's 35 degrees outside, but there's still usable heat energy in air that cold. The system's refrigerant cycle extracts it, compresses it to raise its temperature further, and delivers it through your indoor unit.
The upside of this design is efficiency: a heat pump can deliver more heat energy than the electrical energy it consumes, unlike a furnace or electric resistance heater that's limited by the fuel it burns. The tradeoff is that as outdoor temperatures drop, a heat pump has to work harder to extract the same amount of heat, and its output capacity gradually declines.
The system's efficiency is typically expressed as HSPF (Heating Seasonal Performance Factor) for heating mode and SEER for cooling mode. A higher HSPF rating means the unit extracts more heat energy per unit of electricity consumed, which matters most during the shoulder months of a DFW winter when outdoor temperatures sit in the range where a heat pump performs best. Modern heat pumps also include a reversing valve, the component that lets the same refrigerant circuit switch between heating and cooling modes, along with a defrost control board that manages the periodic defrost cycles needed to keep the outdoor coil clear of ice during cold, humid weather.
Why DFW's Climate Suits Heat Pumps
North Texas has a climate that plays to a heat pump's strengths. Our winters are relatively mild by national standards, with most days sitting in the 40s and 50s and only occasional stretches dropping into the 20s or lower. A heat pump operates at its most efficient in this range, which is exactly the range DFW spends most of its winter in. Compare that to a colder climate like Minnesota or Chicago, where a heat pump alone would struggle for months at a time, and it's clear why heat pumps have become a popular choice for heating in this region.
Because our summers are also long and demanding, a heat pump's ability to handle both cooling and heating in one system is a practical fit for a DFW home, potentially simplifying equipment into a single outdoor unit rather than a separate furnace and air conditioner.
What Happens During a Real Cold Snap
DFW does get the occasional hard freeze, and homeowners understandably worry about how a heat pump performs when temperatures drop into the teens or single digits. As outdoor temperatures fall, a heat pump's heating capacity decreases, meaning it has to run longer to maintain the same indoor temperature. Most residential heat pumps remain reasonably effective down into the 30s and 20s, but as it gets colder, they lean more heavily on backup heat to keep up with demand.
During an extended freeze, you may also notice the outdoor unit going through a defrost cycle, briefly reversing operation to melt ice that forms on the outdoor coil, with a burst of steam or vapor visible during this process. That's normal operation, not a malfunction.
During a defrost cycle, the outdoor fan typically pauses and you may briefly hear the system sound different, almost like it's running backward, because it effectively is: hot refrigerant is being routed through the outdoor coil to melt accumulated frost before switching back to normal heating operation. A well-functioning system completes this in a few minutes. If you notice your outdoor unit caked in a thick layer of ice that doesn't clear between cycles, or running defrost cycles unusually often, that's a sign the defrost control, refrigerant charge, or outdoor fan may need a technician's attention rather than something to wait out.
Understanding Auxiliary and Emergency Heat
Most heat pump systems are paired with a form of backup heat, often electric resistance strips inside the indoor air handler, that kicks in automatically when the outdoor unit alone can't keep pace with the thermostat's setpoint. This is usually labeled "auxiliary heat" or "aux heat" on smart thermostats.
Auxiliary heat is meant to be supplemental, running in short bursts alongside the heat pump during especially cold stretches. If you notice the aux heat indicator staying on constantly, or your energy bill spikes sharply during a cold week, it's worth having the system checked. Constant auxiliary heat use can mean the heat pump itself isn't operating efficiently, or that the system is undersized for the home. There's also an "emergency heat" setting on most thermostats, which shuts the heat pump off entirely and relies solely on backup heat. This should only be used if the outdoor unit has failed and you're waiting on a repair, not as a regular heating mode, since it's considerably less efficient for day-to-day use.
Efficiency and What It Means for Your Bills
Because heat pumps move heat rather than generate it through combustion, they typically cost less to run than electric resistance heat for the majority of a DFW winter. Homeowners switching from an older electric furnace to a heat pump often see a noticeable drop in winter electricity costs, since the heat pump is doing the bulk of the work efficiently and only calling on backup heat during the coldest snaps.
Compared to a gas furnace, the cost comparison depends on local utility rates for electricity versus gas, so results vary by household. What's consistent is that a well-maintained, correctly sized heat pump performs efficiently across the range of temperatures DFW sees for the vast majority of the heating season.
Common Heat Pump Myths in DFW
A few misconceptions come up often enough that they're worth addressing directly:
- "Heat pumps don't really work below freezing." They lose capacity as temperatures drop, but a properly sized system still contributes meaningful heat well into the 20s, with backup heat filling the remaining gap rather than carrying the whole load.
- "A heat pump will spike my electric bill in winter." This is usually true only when the system is undersized, poorly maintained, or leaning on auxiliary heat far more than it should. A correctly sized, well-maintained unit is typically efficient for the bulk of a DFW winter.
- "Heat pumps need to be replaced more often than furnaces." Because a heat pump's outdoor unit runs essentially year-round, handling both heating and cooling duty, wear patterns are different from a furnace that only runs part of the year, but with regular maintenance a heat pump's service life is comparable to a typical air conditioner and furnace pairing.
- "Once it's installed, it doesn't need maintenance in winter." The outdoor coil, refrigerant charge, and defrost controls all benefit from a seasonal check, the same way a furnace does, since these components carry the heating load all winter long.
What We See on DFW Installs
After installing and servicing heat pumps across Irving and the surrounding Metroplex for years, the most common issue we run into isn't the equipment itself, it's sizing and setup. A heat pump that's undersized for the home will lean on auxiliary heat far more than it should, driving up bills and giving homeowners the false impression that heat pumps "don't really work" here. When a system is properly sized for the square footage and insulation of a DFW home, we consistently see it handle the bulk of the winter without much auxiliary heat use at all, only kicking in meaningfully during the coldest week or two of the year.
We also see homeowners forget to check outdoor units after ice storms. Clearing debris and ice buildup around the outdoor coil, and making sure nothing is blocking airflow, keeps the system running as designed through a freeze.
Is a Heat Pump Right for Your Home?
For most DFW homes, a heat pump is a strong option, especially for anyone who wants one system handling both heating and cooling efficiently through our long cooling season and short, mild winter. If you're weighing a heat pump against a traditional furnace-and-AC setup, the right choice depends on your current ductwork, your home's insulation, and your household's cold tolerance during the occasional deep freeze.
Our team can walk through your home, current equipment, and energy goals to help you decide what makes sense. Homeowners already running a heat pump can also ask us about seasonal checks through our maintenance plan to keep the system's defrost cycle, refrigerant charge, and auxiliary heat elements working the way they should before winter arrives. Give us a call at 972-446-2665 to talk through your options, or check out our service area to see if we cover your neighborhood.
Spencer Air Conditioning & Heating — Serving DFW Since 1960. License TACLA115636C