When to Use Emergency Heat on a Heat Pump

What Is Emergency Heat on a Heat Pump?

Emergency heat is a manual backup mode that completely disconnects the outdoor heat pump and runs only the backup electric resistance strips inside your air handler. It costs significantly more to operate and is only appropriate when the heat pump itself cannot run.

Your backup heat strips convert electricity into heat at a 1-to-1 ratio. One unit of electricity in, one unit of heat out. Engineers call that a coefficient of performance (COP) of 1.0, or 100% efficiency.

Your heat pump in normal operation works completely differently. Instead of generating heat, it moves heat. It extracts thermal energy from outdoor air and transfers it inside. That process runs at 300-400% efficiency, or a COP of 3-4. For every unit of electricity it consumes, it delivers three to four units of heat into your home.

That efficiency gap is the entire reason heat pumps exist. Emergency heat cancels it entirely.

One practical note: when EM heat is active, the “EM HEAT” indicator on your thermostat will be lit. If that light is on and you did not flip it manually, switch back to normal heating mode right away. The rest of this post explains why that happens.

What Is Auxiliary Heat, and How Is It Different?

Auxiliary heat is automatic backup that runs alongside the heat pump when temps drop too far for the pump to keep up alone. Emergency heat manually shuts the pump off and runs only the backup strips. These are two separate modes, and confusing them is the root of most EM heat mistakes.

Every heat pump system has two heat sources. The first is the outdoor heat pump unit. The second is a set of backup electric resistance strips inside the air handler - or, in a dual-fuel setup, a gas furnace. When outdoor temperatures drop far enough that the pump cannot hit your setpoint on its own, the system blends in that backup heat automatically. That is auxiliary heat. Your thermostat will display “AUX” when it is active.

You never need to turn auxiliary heat on. The system manages it with no input from you. The backup strips kick in when needed, then back off when the pump can carry the full load again. This is exactly how a cold-climate heat pump system is designed to operate in Minnesota.

Emergency heat is a separate mode entirely. Switching to it manually disconnects the outdoor unit and forces the system to run exclusively on the backup strips. The pump stops. The strips carry everything.

The visual tell is simple. “AUX” on your thermostat means everything is working normally. “EM HEAT” means the pump is off. Check which is showing and act accordingly.

Why Does Emergency Heat Cost So Much More?

Your heat pump moves existing heat from outdoor air into your home. Resistance strips generate heat from scratch using only electricity. Moving heat is far more efficient than producing it, and that gap shows up on your energy bill every hour the wrong mode runs.

At 20 degrees F outside, a heat pump uses roughly 1.7 kWh per hour to produce a given amount of heat. Electric resistance strips burn through about 4.9 kWh per hour for identical output - nearly three times the electricity for the same warmth.

Scale that over a week and the numbers become hard to ignore. Running emergency heat for 12 hours per day over seven days costs approximately $196.56. The same week in normal heat pump mode costs roughly $32.76 - a difference of $163.80 for the same amount of heat delivered.

For a Twin Cities homeowner who installed a heat pump to lower energy costs, spending two or three weeks per winter in EM mode can erase most of the efficiency gains for the entire heating season. The heat pump only delivers its efficiency advantage when it is actually running.

Two Hidden Triggers Most Heat Pump Owners Miss

Most accidental emergency heat use does not come from someone deliberately flipping a switch. It comes from two situations that look like ordinary thermostat use but trigger backup heat without the owner realizing it.

The Thermostat Setback Trap

Raising your thermostat setpoint by more than 2 degrees F at once automatically triggers auxiliary or emergency heat, even on a day that is nowhere near cold enough to justify it. The system reads a large jump as a demand for maximum heat output and pulls in the backup strips to get there faster.

This is one of the most common and repeated mistakes new heat pump owners make. You wake up, the house is 65 degrees, you push the thermostat to 70, and you have just triggered strip heat for the next 30-60 minutes. You did not flip the EM switch. You raised the setpoint five degrees at once.

The fix is simple: raise the setpoint in 1-2 degree increments and let the pump catch up between adjustments. If you use a smart thermostat, program it for gradual morning ramp-ups rather than one large jump. Preventing this trigger automatically is one of the clearest efficiency benefits a smart thermostat delivers on a heat pump system.

The Defrost Cycle

On cold days, frost accumulates on the outdoor heat pump coil. When buildup reaches a threshold, the system automatically enters a defrost cycle: it briefly reverses refrigerant flow to melt the ice off the coil. During that cycle, the system activates the backup heat strips for a few minutes to keep your home warm while the pump defrosts.

This is intentional. It is not a malfunction. During the defrost cycle you might notice slightly cooler air from the vents, a different sound from the outdoor unit, or steam rising from the outdoor unit as ice melts.

None of that is an emergency. It is designed behavior. The defrost cycle ends on its own within a few minutes and the pump returns to normal operation. Switching to emergency heat every time you see steam from the outdoor unit is one of the fastest ways to double your heating bill without accomplishing anything.

Does Cold Weather in Minnesota Mean I Should Use Emergency Heat?

No. Modern cold-climate heat pumps installed in the Twin Cities are engineered for Minnesota winters. They operate efficiently at 0 degrees F and below. Outdoor temperature alone is not a reason to flip the EM switch.

This is the question we hear most from new heat pump owners after their first January cold snap. The reasoning feels intuitive: it is minus ten degrees outside, the emergency heat option is right there, and surely it must help more than the pump can manage in that kind of cold. That reasoning is backward.

Minnesota sits in ASHP climate zones 6 and 7. Older standard heat pumps did lose effectiveness below 40 degrees F. That was the historical argument against heat pumps in cold climates, and it was accurate for that generation of equipment. But modern cold-climate air-source heat pumps operate efficiently down to 0 degrees F, with many models rated to -13 degrees F or lower. A field study by the Center for Energy and Environment - a Minnesota nonprofit - found that modern inverter-driven heat pumps are 2-4 times more efficient than standard electrical heating even at moderate winter temperatures.

In practical terms: at -10 degrees F in January, your cold-climate heat pump is still delivering more heat per kilowatt than your resistance strips can generate. Switching to emergency heat at that point costs you more money for identical comfort.

The homeowners who bought a heat pump rated for these conditions already paid for the engineering to handle a Minnesota winter. Using EM heat in a cold snap is like buying snow tires and then refusing to drive on snow.

If you want the full data on how cold-climate heat pumps perform at extreme Minnesota temperatures, our post on heat pump performance below zero in Minnesota covers the field research in detail. If you are still deciding whether a heat pump is right for your home, heat pumps in Minnesota - are they a good fit? walks through the full picture, including efficiency ratings and sizing considerations for our climate.

When Should You Actually Use Emergency Heat on a Heat Pump?

In exactly three situations, and outdoor temperature is not among them. Emergency heat is a bridge for when the pump cannot run, not a tool for cold weather, slow warm-ups, or general winter discomfort.

Here are the three legitimate reasons to manually switch to emergency heat:

1. Your HVAC technician instructs you to. If our team is diagnosing a problem with the outdoor unit and needs the pump offline - while waiting for a part, completing a repair, or running a diagnostic sequence - we will tell you explicitly to switch to EM heat for that window. Follow that instruction. Turn it off when we confirm the repair is complete.

2. The heat pump has completely failed. If the outdoor unit has stopped running entirely and your home has no working heat source, emergency heat is the right call. This is the situation the setting was designed for. Use it as a temporary bridge while you wait for a technician - and call us to get that appointment scheduled.

3. The outdoor unit is physically damaged. Storm debris, significant ice accumulation from a freezing rain event, or a fallen branch can make it unsafe to run the pump. Forcing a damaged unit to run risks further damage to the refrigerant system and electrical components. Switching to EM heat protects the equipment while you wait for service.

Outside of those three situations, leave the switch alone. Cold snaps, wind chills, a slow warm-up after a setback, a house that feels chilly in January - none of these belong on this list. If something seems wrong, the right move is a service call, not the EM switch.

What If the Heat Pump Is Not Keeping Up?

If your home is losing ground on a cold day and the system seems to be struggling, call a technician. A pump that cannot maintain temperature in conditions it should handle is signaling a problem. Emergency heat will mask the symptom and allow that problem to continue.

Start by checking the filter. A clogged air filter is the single most common cause of reduced heat pump output, and addressing it costs nothing. A dirty filter restricts airflow, forces the system to work harder, and significantly cuts the heat delivered to your home. If your filter is overdue, replace it before making any other calls.

If the filter is clean and the system is still not keeping up, something needs a technician’s attention. It might be low refrigerant, a dirty coil, a failing defrost board, or a compressor issue. These problems do not fix themselves, and running on emergency heat while ignoring them means you pay higher operating costs and let the underlying issue worsen.

Northern One Hour is locally owned and operated in Ramsey, MN, and our team serves the full Twin Cities area. We back every visit with our on-time promise - “Always On Time… Or You Don’t Pay a Dime!(R)” - because we know a struggling furnace or heat pump does not give you time to wait around for a no-show. Call (763) 260-6662 or book online to schedule a heat pump diagnostic.

Minnesota Rebates: Maximize Your Heat Pump Investment

If you have a heat pump installed in the Twin Cities, or are considering one, the current utility rebate landscape makes the economics favorable - and running your system correctly from the start protects that investment.

Xcel Energy currently offers up to $2,000 for qualifying cold-climate heat pump installations, with applications accepted through September 30, 2026. CenterPoint Energy offers $1,100 for dual-fuel systems that pair a heat pump with a high-efficiency gas furnace, with a required programmable switchover point at 40 degrees F or below. Contact your utility directly for current program terms and to confirm eligibility.

One important note: the federal 25C energy efficiency tax credit that previously covered heat pump installations expired December 31, 2025. State and utility programs remain the primary available incentives for new installations at this time.

Our updated breakdown of available incentives - including income-qualified programs and utility-specific requirements - lives at Minnesota heat pump rebates and tax credits.

Understanding how your system actually works, including what emergency heat is for and what it costs when misused, is part of protecting the return on that investment over the long run.

Simple Habits That Protect Your Heat Pump’s Efficiency

Getting the most from a heat pump is largely about avoiding a handful of common mistakes. These practices cost nothing and preserve the efficiency advantage the system was installed to deliver:

• Never raise the thermostat setpoint by more than 2 degrees F at once. Raise it in single-degree steps and let the pump catch up between each one.
• If you use a programmable or smart thermostat, set gradual morning ramp-ups. A sharp jump from a nighttime setback triggers backup heat exactly the same way a manual thermostat bump does.
• When the outdoor unit sounds different for a few minutes, or you see steam from it on a cold day, leave the system alone. The defrost cycle ends on its own.
• Check the “EM HEAT” indicator on your thermostat a few times per winter. If it is lit and you did not turn it on, switch back to normal heating mode immediately and note whether a large setpoint jump preceded it.
• Replace your filter on schedule. A clean filter is the lowest-cost efficiency improvement available for any heat pump system.
• Schedule an annual maintenance visit before the heating season. Our heat pump repair and maintenance services include a full system check, refrigerant verification, and coil inspection - the kind of proactive service that catches problems in September rather than January.

Emergency heat is a safety net. It exists for the specific situations where the pump genuinely cannot operate. For cold snaps, defrost cycles, slow warm-ups, and every ordinary Minnesota winter - leave the switch alone. The pump can handle it.

If your heat pump is not keeping up this winter, or if you just want confirmation that your system is ready before temperatures drop, Northern One Hour is locally owned and ready to help. Call (763) 260-6662 or book online. We serve the Twin Cities from Ramsey, and we show up when we say we will.