What Is EM Heat? Emergency Heat Mode Explained (NEPA Homeowner's Guide)

If you have a heat pump and your thermostat shows an option labeled 'EM Heat' or 'Emergency Heat,' you've probably wondered what it does — and whether you should be using it during a cold Scranton winter. The short answer: EM Heat is a backup mode, not a 'turbo' button. Used correctly, it keeps your home safe when something goes wrong. Used incorrectly, it can double or triple your heating bill.

This guide breaks down exactly what emergency heat is, when to turn it on, when to leave it alone, and what to do if your system is stuck in EM Heat mode here in Northeast PA.

How a heat pump heats your home (the quick version)

A heat pump doesn't burn fuel. It moves heat from the outdoor air into your house. Even in cold weather, there's usable heat outside — modern systems can pull warmth from air as cold as the teens or single digits. That's the 'normal' heating mode, and it's the most efficient way to heat a home.

But when it gets very cold, or when the outdoor unit can't keep up, the system needs a backup. That backup is called auxiliary heat (aux heat) — usually electric resistance coils inside your air handler, or in some homes, a gas or oil furnace paired with the heat pump. Aux heat kicks in automatically when needed and turns off again when the heat pump can handle the load.

So what is EM Heat?

EM Heat is you manually telling the system: 'Stop trying to use the outdoor heat pump. Run only the backup heat.' It bypasses the heat pump entirely.

That's a useful setting in exactly one situation: the outdoor unit is broken, frozen solid, or otherwise can't run, and you need heat right now while you wait for a repair. It's a safety net, not a winter setting.

When to use EM Heat

• The outdoor unit is encased in ice and won't defrost.
• The outdoor unit is making loud grinding or banging noises and you've shut it off.
• A tree branch, ice storm, or accident has damaged the outdoor unit.
• An HVAC technician has told you to switch to EM Heat until they arrive.

When NOT to use EM Heat

• It's just cold outside. Heat pumps are designed for NEPA winters and will engage aux heat on their own.
• Your house is warming up slowly. That's normal — heat pumps deliver steadier, lower-temperature air than a furnace.
• You want the house to feel warmer faster. EM Heat won't reach the setpoint any quicker; it just runs the expensive backup the whole time.
• You forgot why you turned it on last week. Switch it back to Heat and let the system manage itself.

Why EM Heat costs so much more

A heat pump in normal mode is roughly two to three times more efficient than electric resistance heat, because it's moving heat instead of generating it. When you flip to EM Heat, you're paying for every BTU with straight electricity (or fuel, if you have a dual-fuel system). On a cold Scranton week, leaving EM Heat on by accident can easily add $100–$300 to a single month's bill.

Most thermostats light up a small indicator — often a snowflake, a wrench, or the words 'AUX' or 'EM HEAT' — whenever backup heat is engaged. If that light is on constantly even though you didn't change the setting, that's a sign something is wrong with the heat pump and you should call a technician.

Troubleshooting: stuck on EM Heat

The EM Heat light won't turn off

First, check the thermostat mode. Make sure it's set to 'Heat,' not 'Emergency Heat' or 'Em Heat.' If it's already on Heat and the indicator is still lit, the system has decided the heat pump can't keep up and is calling for aux heat on its own. That's appropriate during a deep cold snap, but if it's happening in mild weather, something is wrong — a low refrigerant charge, a frozen outdoor coil, a failed defrost board, or a stuck reversing valve are the usual suspects.

The outdoor unit is iced over

A light coating of frost is normal in NEPA — the unit will defrost itself every 30–90 minutes. A solid block of ice covering the coil or fan is not normal. Switch to EM Heat to stop the heat pump from running, then call for service. Never chip ice off with a tool; you can puncture the coil.

The system runs but the house never warms up

If you've been in EM Heat for a while, switch back to Heat and see if it improves. If you're already on Heat and the house is still cold, check the air filter (a clogged filter can cause both efficiency loss and aux heat lockouts) and the breakers for both the indoor and outdoor units.

NEPA-specific advice for heat pump owners

Scranton, Dunmore, Clarks Summit, and the rest of Lackawanna County get the full range of winter weather — single-digit cold snaps, ice storms, lake-effect bursts, and the occasional power blip. A few habits keep your heat pump happy through all of it:

• Keep the outdoor unit clear of snow drifts and at least 18 inches above ground level if you're in a heavy-snow microclimate.
• After an ice storm, look at the outdoor unit before assuming the system is broken. Visible ice = call for service, not EM Heat for a week.
• Change the air filter every 1–3 months during heating season. Restricted airflow is the #1 cause of unnecessary aux/EM heat usage.
• Schedule a fall tune-up. Catching a weak capacitor or low refrigerant in October is far cheaper than an emergency call in January.

When to call Berge HVAC

If your heat pump is iced over, your EM Heat light is on for no clear reason, or your house just isn't getting warm, don't ride it out — every day on emergency heat is money out the door, and a small problem in December becomes a big problem in February. We're local, owner-operated, and available 24/7 for heating emergencies across Scranton and Northeast PA.