Key Points
- Emergency heat is a backup heating mode that activates when your heat pump can no longer extract heat from outdoor air — it relies on a secondary source (electric resistance strips, gas, or oil) to heat your home directly.
- According to the U.S. Department of Energy, heat pumps are most efficient in mild climates and can lose effectiveness as temperatures approach or drop below freezing — which is why Texas heat pump owners need to understand emergency heat before a storm arrives.
- Heat pumps stop working efficiently around 35°F — at or below this threshold, there isn’t enough heat in the outdoor air for the pump to transfer, and the system must rely on its backup heating source.
- You should only switch to emergency heat manually when your heat pump has stopped functioning and your home isn’t warming up — never use it as a precaution simply because temperatures are low.
- Emergency heat is significantly more expensive than standard heat pump operation — all-electric backup systems in particular can drive up energy bills rapidly during extended use.
- Protecting your outdoor heat pump unit from snow and ice buildup during winter storms is the single most important step DFW homeowners can take to avoid emergency heat situations in the first place.
- Contact Ellis AC & Furnace Repair for fast emergency HVAC service throughout the Dallas-Fort Worth area during winter storms and year-round.
Texans are currently experiencing an unprecedented winter storm. People are increasingly wary of car accidents, power outages, and problems with heating their homes. Many homeowners in the south depend upon heat pumps to heat and cool their homes — this is because it’s an incredibly effective method in mild climates. However, with snow and ice building up it may be time to switch your heat pump to emergency mode.
How Do Heat Pumps Work?
A heat pump is HVAC equipment installed outside of your home. The pump redistributes hot air to heat and cool your home. When it’s cold outside, the unit pulls heat out of the air and into your home. When it’s too hot inside, the pump pulls hot air out of your home and transfers it outside. However, this heating method doesn’t work in freezing temperatures.
Why heat pumps are common in Texas — and why winter storms create problems: Heat pumps are the dominant residential HVAC choice across the Dallas-Fort Worth area because North Texas winters are typically mild enough that the system can extract heat from outdoor air throughout the season. In a normal DFW winter, temperatures rarely stay below freezing for more than a day or two — which is exactly the range where heat pumps work best. But during an extreme winter storm event, sustained sub-freezing temperatures eliminate the outdoor heat the pump depends on, pushing the system into its backup mode. Understanding how that backup mode works — and when to use it correctly — is essential knowledge for every DFW homeowner with a heat pump system. For questions about your specific heat pump system, Ellis AC technicians are available throughout the Dallas-Fort Worth area.
What Is Emergency Heat?
When the temperature drops below freezing and your heat pump isn’t working, you can set your thermostat to emergency heat. This can also be automatically triggered at 35 degrees Fahrenheit. When the temperature gets too low, your pump won’t function properly because there isn’t any heat for the pump to transfer. The system will depend on a furnace or heat strips to heat your home.
When you switch to emergency heat, your pump will stop trying to extract heat from the outside and will only utilize the secondary heating method.
The difference between “Auxiliary Heat” and “Emergency Heat” on your thermostat: Many DFW homeowners confuse these two settings. Auxiliary heat (sometimes labeled “Aux Heat”) activates automatically when the heat pump is running but needs supplemental help to reach the set temperature — it works alongside the heat pump and is a normal part of system operation in very cold weather. Emergency heat is different: it completely bypasses the heat pump and runs only the backup heating source. You’ll typically see an “Em Heat” or “Emergency Heat” setting on your thermostat — this is a manual override that should only be used when the heat pump itself has failed. If your thermostat shows “Aux Heat” activating on its own, that’s normal system behavior and not a cause for concern.
When to Use Emergency Heat
You should only use emergency heat — as the name suggests — in emergency situations. Turn on the emergency heat if your heat pump stops functioning and your home isn’t warming up. This happens quite often when temperatures hit the freezing point.
If your heating system doesn’t automatically switch to emergency heat, you should do it manually. This will help prevent damage to your primary unit and heat your residence faster.
Specific situations that warrant switching to emergency heat manually:
- Your heat pump is running but producing no warm air despite the thermostat being set correctly
- The outdoor unit has stopped operating entirely — you can’t hear or feel it running
- Your home temperature is dropping despite the system appearing to run
- An HVAC technician has advised you to switch while they diagnose or repair the primary unit
If any of these conditions apply during a winter storm, switching to emergency heat is the right call. Contact Ellis AC & Furnace Repair for emergency HVAC service while your home is being heated by the backup system — the sooner the heat pump is diagnosed, the less you’ll spend on backup heating costs.
Cost of Using Emergency Heat
Switching to emergency heat can be expensive if you have an electric heating system. For this reason, you shouldn’t use emergency heat unless it’s absolutely necessary. You don’t necessarily need to turn the emergency heat on just because it’s cold — it is only necessary if your pump stops working altogether.
Running your emergency heat increases your energy usage and drives up your energy bill. If your system is all-electric, you can stand to lose quite a bit of money heating your home this way for extended periods of time. However, if your backup heating system runs on gas or oil, you may get a bit of a price break.
Why the cost difference is so significant: A heat pump operating normally delivers 2–3 units of heat energy for every unit of electricity it consumes — that efficiency ratio is what makes it cost-effective. Electric resistance heat strips (the most common backup in DFW all-electric systems) convert electricity to heat at a 1:1 ratio — no efficiency multiplier. Running electric backup heat for even 24 hours during a severe storm can cost several times what a normal day of heat pump operation would cost. This is why the distinction between “Aux Heat” (automatic, normal) and “Emergency Heat” (manual override, expensive) matters so much financially. Minimize the duration of emergency heat use by calling Ellis AC for fast diagnosis and heat pump repair as soon as possible.
Protect Your Heat Pump
You should check your heat pump for snow and ice buildup during winter months. Do your best to keep it clear. If you notice too much debris, call an HVAC repairman to get the unit fixed. If you take care of it quickly, you could save a lot of money on future repairs or a replacement.
Practical steps DFW homeowners can take to protect their outdoor heat pump unit during a winter storm:
- Clear snow accumulation from the top of the unit using a broom — never use a shovel or sharp tools that could damage the coil fins
- Keep the area around the unit clear of ice and debris — at least 18–24 inches of clearance on all sides
- Never cover the unit with a tarp or plastic sheeting — heat pumps need airflow and have their own built-in defrost cycles
- If you see ice on the coil fins that isn’t clearing within an hour or two, the defrost cycle may have failed — call for service rather than attempting to chip the ice away
- Elevate the unit above typical snow depth if possible — many DFW installations are at ground level, which makes them more vulnerable to drifting snow accumulation
Do not run the heat pump if the unit is encased in ice — this can cause compressor damage. Switch to emergency heat and contact Ellis AC & Furnace Repair for a winter storm inspection. Our team also offers heat pump maintenance visits before the season to verify defrost cycle function and overall system readiness.
Key Takeaways
Emergency heat is a backup heating mode for when your heat pump can no longer function in freezing temperatures — it bypasses the heat pump entirely and relies on electric strips, gas, or oil to heat your home directly. The DOE confirms heat pumps lose efficiency as temperatures approach freezing, which is why Texas winter storm events push DFW systems into backup mode. Only switch to emergency heat manually when the heat pump has stopped working — not simply because it’s cold. Auxiliary heat activating on its own is normal; the “Em Heat” manual override is what to avoid unless the pump has failed. All-electric backup systems are significantly more expensive to run than heat pump operation, making fast professional repair the priority. Protect your outdoor unit from snow and ice accumulation but never attempt to chip ice from the coil or cover the unit with a tarp. Contact Ellis AC & Furnace Repair for emergency HVAC service and heat pump repair throughout the Dallas-Fort Worth area.
Call Ellis AC for Winter Storm HVAC Help in DFW
Our HVAC professionals know how important it is to maintain your heating system during a Texas winter storm. It’s more important than ever with all 254 Texas counties under winter storm warnings. If you notice excessive ice buildup on your heat pump or your home isn’t warming up enough, call us immediately — we’re here to help keep you safe and warm.
Contact Ellis AC & Furnace Repair for fast emergency HVAC repair and heat pump repair throughout the Dallas-Fort Worth area. For ongoing protection, ask about our heat pump maintenance plans to keep your system ready before the next storm arrives.