when should you turn emergency heat on

You should only turn emergency heat on when your heat pump can’t heat your home properly because something is wrong with it, not just because it’s very cold outside.

When should you turn emergency heat on?

The true purpose of emergency heat

On most heat-pump thermostats, “EM Heat” or “Emergency Heat” is a backup mode that lets your system use the secondary heat source (usually electric strips or a gas/oil furnace) without the outdoor heat pump running.

It is designed as a temporary workaround so your home can stay warm while the main heat pump is malfunctioning or shut down for repairs, not as a stronger “turbo heat” for cold nights.

Situations when you should use emergency heat

Turn on emergency heat if:

1. The heat pump is broken or clearly damaged
   • Outdoor unit crushed by a fallen tree or debris.

 * Visible damage, disconnected lines, or the unit will not start at all.

2. The heat pump runs but your home stays cold
   • Thermostat is calling for heat, but the indoor temperature keeps dropping or never reaches the set point, even after long run times.

 * This often suggests a heat pump failure, low refrigerant, compressor issue, or fan problem.

3. The outdoor unit is frozen and will not defrost
   • Light frost on coils is normal in winter, but a solid block of ice that doesn’t clear after a defrost cycle is a problem.

 * In that case, switch to emergency heat and schedule an HVAC technician.

4. A technician or your HVAC company tells you to
   • Sometimes they’ll ask you to switch to EM Heat to prevent damage while you wait for service.

In all of these cases, the key sign is: your primary heat pump cannot safely or effectively heat your home, so you’re using the backup system temporarily.

Situations when you should not use emergency heat

Avoid turning on emergency heat in these common scenarios:

• “It’s just really cold outside”
  Modern heat pumps are designed to work in freezing weather and will automatically bring on auxiliary/second-stage heat when needed without you touching EM Heat.

Manually switching to EM Heat in normal cold weather bypasses the efficient heat pump and jumps straight to the expensive backup.

• You want the house to heat up faster
  Emergency heat doesn’t magically heat faster; it just forces the costlier backup to run alone.

If your house warms slowly but does eventually reach set temperature, the system may be correctly sized and simply working hard in colder weather.

• You see “Aux Heat” and think it’s an error
  “Aux” or “Stage 2” heat often comes on automatically in low outdoor temperatures. That’s normal and not the same as manually choosing EM Heat.

In short, don’t flip to emergency heat just because the forecast looks icy or you’re impatient for warmth.

Cost and efficiency: why you should be cautious

Emergency heat is usually much more expensive to run than the heat pump:

• Heat pumps move heat and are generally energy-efficient.
• Emergency heat often relies on electric resistance strips (like a giant space heater) or runs a furnace by itself, which can dramatically increase your energy usage and bill.

Many HVAC pros recommend using EM Heat only as long as needed to keep the house safe and livable , then returning to normal heat once the main system is repaired.

Think of it like a spare tire on your car: great in a pinch, but not something to drive on every day.

Quick reference table

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Situation	Use Emergency Heat?	Why
Outdoor unit damaged (tree, impact, clear failure)	Yes	Main heat pump cannot safely run; backup keeps home warm until repair.
Heat pump running but house won’t warm up at all	Yes (temporarily)	Likely malfunction; EM Heat buys time while you schedule service.
Outdoor unit frozen in solid ice that won’t defrost	Yes	Continuing to run may damage equipment; switch to backup and call a pro.
Very cold outside, but system still heats the house (possibly with Aux)	No	System is operating as designed; EM Heat would just cost more.
You want faster heating after turning thermostat up	No	EM Heat isn’t a “turbo” mode, just a less efficient backup.
HVAC technician instructs you to use EM Heat	Yes	They may be protecting the system or testing the backup heat.

Forum-style perspective and common myths

“I turn on emergency heat any time it drops below freezing. It’s there for cold weather, right?”

This is one of the most common myths. In reality, the thermostat and system decide when to add auxiliary heat in cold weather automatically , without you flipping to EM Heat.

When you manually switch, you often pay more for the same comfort because you’re forcing the system onto the least efficient heat source.

“My EM Heat light came on—do I have to panic?”

If you turned the setting to EM Heat yourself, the light simply confirms you’re in backup mode.

If you didn’t touch the thermostat and see an emergency indicator or error message, that can be a sign the system detected a problem and you should call a pro, using backup heat only as needed to stay safe.

How to handle it step by step

If you’re wondering whether to turn on emergency heat, you can walk through this quick checklist:

1. Check comfort and temperature
   • Is the house actually not warming up, or just taking longer because it’s very cold?
2. Inspect the outdoor unit (safely from a distance)
   • Any obvious damage, heavy ice block, loud grinding noises, or the unit not running at all?
3. Look for normal “Aux” or “Stage 2” indicators
   • If you only see “Aux Heat” during very cold weather, that’s usually normal, not an emergency.

4. If there’s a real failure, switch to EM Heat
   • Set the thermostat to EM Heat to keep your home warm, then schedule HVAC service as soon as possible.

5. After repair, switch back
   • Once your main heat pump is working properly again, return the thermostat to the regular Heat setting.

SEO-style meta description

When should you turn emergency heat on? Use it only when your heat pump is malfunctioning or can’t heat your home, not just because it’s cold, since it’s far less efficient and more expensive.

TL;DR: Turn emergency heat on only if your heat pump is broken, badly iced over, or not heating the house, and you need temporary backup heat while waiting for repair—never just because it’s a cold day. Information gathered from public forums or data available on the internet and portrayed here.