Every winter, ElectriCities’ Retail Energy Services team receives numerous questions about emergency heat: What is it? When should we use it? And why does it make our electric bills so high?
To provide some clarity on this important topic, we checked with John Keever, Lead Energy Services Specialist at ElectriCities. Along with helping ElectriCities members and their customers save energy for nearly two decades, he’s a former HVAC technician.
Here’s our Q&A with John.
Q: What is emergency heat?
A: When it’s cold outside, your heating system works to keep your house warm, usually with a gas furnace or electric heat pump. If you have a heat pump, there are two heating modes on the thermostat: HEAT and EMERGENCY HEAT. Emergency heat, also known as auxiliary heat, refers to electric resistance heating. This involves little coils of wire with an electric current running through them in your air handler—similar to what you see in a hair dryer. While electric resistance heaters (like space heaters) are reliable and inexpensive to purchase, they can be expensive to operate. They are 100% efficient, meaning one unit of energy consumed equals one unit of heat produced.
Q: How is a heat pump more efficient?
A: What if, instead of creating heat, we could move existing heat into the house? That’s exactly what a heat pump does. It transfers heat energy from outside to inside using a refrigerant cycle, much like a refrigerator in reverse. This process enables heat pumps to be more than 100% efficient, because they are moving heat rather than generating it. This is what happens when a heat pump’s thermostat is set to HEAT mode. Pretty cool, right?
Q: Why have a backup?
A: Heat pumps, while efficient, can be a bit finicky. They need to work harder when there’s not enough heat to move around, they don’t perform well with ice buildup, and like any equipment, they can break down. That’s why having a backup source of electric resistance heat is a smart idea.
Q: What are some common misconceptions?
A: Some homeowners believe that heat pumps don’t work in cold weather, and they switch to EMERGENCY HEAT mode when temperatures drop. However, most modern thermostats are designed to automatically activate auxiliary heat when needed, typically in three scenarios:
- When the heat pump can’t recover heat quickly enough due to extreme cold.
- When the thermostat set point is manually adjusted significantly higher.
- When the outside compressor detects frost and goes into defrost mode. During defrost mode, the heat pump temporarily switches to air conditioning mode to melt ice off the outside unit, using auxiliary heat to ensure warm air continues to flow inside.
Q: When should we manually use emergency heat?
A: You should only manually switch to EMERGENCY HEAT mode if your heat pump is malfunctioning and you need to keep your house warm while waiting for repairs. In rare cases, such as during freezing rain, ice could build up on the compressor fan fins and potentially cause damage. In this situation, running EMERGENCY HEAT mode can prevent the compressor fan from spinning and protect your equipment. However, this is an uncommon scenario.
Q: How does using emergency heat impact our electric bills?
A: Using EMERGENCY HEAT or AUX mode can significantly increase your electric bill compared to regular HEAT mode. Be careful not to activate EMERGENCY HEAT mode inadvertently—a very easy mistake to make. Only use these settings in true emergencies when you need immediate warmth.
If you have any questions or want to learn more about energy efficiency, contact the energy experts on ElectriCities’ Retail Energy Services team. Along with being a valuable resource for education, the team will also work with you to provide free energy audits to help your customers save on their energy bills.