What is EM Heat on Your Thermostat?

Have you ever glanced at your thermostat on a freezing Worcester morning and noticed “EM Heat” or “Emergency Heat” glowing on the display? If you’re like most homeowners, this mysterious setting probably left you wondering what it means and whether you should be concerned.

Understanding emergency heat is crucial for anyone with a heat pump system, especially during New England’s brutal winter months.

Emergency heat is your heating system’s backup plan when your primary heat pump can’t keep up with demand or stops working properly. While it keeps your home warm when you need it most, running on EM heat for extended periods can significantly increase your energy bills.

What is EM Heat

Emergency heat, often labeled “EM Heat” or “E-Heat” on your heat pump thermostat, is a secondary heat source designed specifically for heat pump systems. It’s a setting that controls your home’s backup heating when the primary heating system fails. When you see this light on, your system has switched from its normal, energy-efficient heat pump operation to a backup heating source.

Normal Heat Pump Operation:

• Extracts heat from outside air and transfers it inside using refrigerant technology
• Uses the heat pump to extract heat efficiently from the outside air
• Highly energy-efficient in moderate outdoor temperature conditions
• Most cost-effective heating method for your home

Emergency Heat Mode:

• Locks out the heat pump completely and relies solely on the backup heat source
• Functions through electric heat strips or a backup furnace
• Significantly higher cost to run an em heat pump compared to normal operation
• Should only activate emergency heat during genuine system failures

In Worcester MA’s climate, where temperatures drop regularly below freezing, your heat pump needs this secondary heating system. The Comfort Specialists often explain to homeowners that stands for emergency heat and isn’t something to fear, but it’s definitely something to understand and monitor.

How Does Emergency Heat Work?

During normal operation, your heat pump works remarkably hard to keep your Worcester home comfortable. It pulls heat from the outside air (yes, even when it’s cold) and moves it indoors through a refrigeration cycle. The heat pump works efficiently when outdoor temperature stays above 25-30°F.

When temperatures drop or your heat pump stops working, the system needs help. That’s when em heat work begins. Most systems use electric heat strip coils, similar to what you’d find in an electric furnace. Some homes have a gas or oil furnace as their backup heat source instead.

The key difference is efficiency. Your heat pump might produce three units of heat for every unit of electricity. Emergency heat produces only one unit of heat per unit of electricity, making it roughly three times more expensive to operate.

When Should You Use Emergency Heat?

Many homeowners accidentally turned their thermostat to emergency heat and left it running for days, resulting in shocking utility bills. Understanding when to use em heat can save you hundreds of dollars.

Genuine Emergency Situations:

• Your heat pump is broken or has completely stopped working
• The outdoor unit is frozen solid and won’t defrost properly
• You hear grinding or unusual noises requiring immediate repair
• A technician has advised you to switch your thermostat to EM heat mode
• The heat pump is damaged and cannot provide heat efficiently

When NOT to Use EM Heat:

• Your home feels slightly cool but the properly functioning heat pump is running
• You want to heat your home faster (switching to emergency heat won’t work faster)
• You’re trying to save money (em heat uses significantly more energy)
• The weather forecast predicts cold temperatures (give the heat pump time to work)

If your EM heat light comes on automatically, your system is telling you something needs attention. While it will keep your house warm temporarily, contact The Comfort Specialists for heating repair and installation services as soon as possible.

EM Heat vs Aux Heat: What’s the Difference?

This confusion trips up many homeowners. Your thermostat setting might show “Aux Heat” or auxiliary heat instead of emergency heat. The general rule of thumb: they use the same heating elements but function differently.

Auxiliary Heat:

• Activates automatically when the heat pump needs extra help to heat a space
• Works alongside your primary heat pump as a secondary source
• Comes on during very cold weather when heat from the outside air isn’t enough heat
• Normal part of used in heat pump systems operation

Emergency Heat Setting:

• Usually requires manual activation when you switch your thermostat
• Completely shuts off the heat pump and runs solely on the backup heating system
• Used only when the heat pump fails or is not working
• Emergency heat is meant for temporary use until cleaning, repair, or installation occurs

If you see aux heat occasionally during cold Worcester winters, don’t panic. That’s your hvac system working as designed. If emergency heat or auxiliary heat stays on constantly, check if you accidentally turned the thermostat setting.

The Real Cost and Warning Signs

Let’s talk numbers because this is where the emergency heat source really impacts your wallet. A typical heat pump in Worcester might cost $150-200 per month to run during winter. Run an em heat pump for the entire month, and that bill could jump to $450-600 or more.

Warning Signs Requiring Professional HVAC Service:

• EM heat indicator stays lit constantly for more than 24 hours
• Your secondary heating system can’t maintain temperature even in emergency heat mode
• Strange burning smells when the electric heat operates
• Ice buildup on outdoor unit persists despite defrost cycles
• The amount of heat produced seems insufficient to keep your home comfortable

Before calling for emergency service, verify your thermostat is set correctly and you didn’t accidentally switch to the em heat setting. Clear snow or debris from the outdoor unit. If these steps don’t resolve the issue or your emergency heat is a setting that’s been active for more than a day, it’s time to call The Comfort Specialists for professional furnace repair and maintenance.

Keeping Your System Running Right

Prevention beats expensive repair bills every time. Regular maintenance keeps your heat pump system running efficiently and reduces the chances you’ll need to turn on your em heat at all. Worcester homeowners should schedule professional hvac cleaning and inspection twice yearly.

Simple Maintenance Steps:

• Keep your outdoor unit clear of snow, leaves, and debris for proper airflow
• Change air filters monthly during heating season to heat efficiently
• Schedule professional cleaning and inspection services in spring and fall
• Monitor when auxiliary or emergency heat activates to catch problems early

The Comfort Specialists offers comprehensive maintenance plans that include priority emergency service. Our licensed and insured technicians use a tech-driven approach to catch small problems before they become expensive emergencies requiring major installation or repair work.

The Bottom Line

Emergency heat serves an important purpose as a backup heat source, keeping your home comfortable when your primary heat pump can’t extract heat from outside air effectively. However, emergency heat is meant for genuine emergencies only. Understanding the appropriate way to use this setting, recognizing warning signs, and knowing when to call for professional help protects both your comfort and your wallet.

If you’re dealing with an em heat vs normal operation situation or want to ensure your heating system is ready for winter, contact The Comfort Specialists. We provide complete residential services including installation, repair, cleaning, duct cleaning Worcester, and 24/7 emergency service. Our transparent pricing and first-time-right approach mean you get honest answers and real solutions.

Don’t let the emergency heat setting catch you off guard this winter. Proper maintenance and understanding when to use the emergency heat function go a long way toward keeping your home comfortable and your energy bills reasonable all season long.