What’s The Difference Between Auxiliary and Emergency Heat?

A heat pump is a type of heating, ventilation, and air conditioning system (HVAC) that can be used for both heating and cooling. 

If you are considering a heat pump system, or maybe if you have one already, you may have read the terms and wondered – is auxiliary heat the same as emergency heat? Although they sound similar, the two modes are not the same at all. 

They are actually quite different and have specific uses. In this article, we’ll take a look at both so you can better understand your HVAC system. 

Aux heat vs emergency heat – An overview

In this section let’s look at some of the primary differences between the purposes and uses of aux heat vs emergency heat. 

What is auxiliary heat? 

Aux heat, or auxiliary heat, is an automatic function that your heat pump will choose when the ambient temperature drops. This mode will allow the heat pump to continue warming your home but involves the use of additional gas or electricity, which makes for a negative impact on your energy use and bills.

What is emergency heat?

Not every heat pump will have an emergency heat mode. For those that do have this function, emergency heat is used when the heat pump is down for maintenance or repair or when the temperature falls below 30 degrees Fahrenheit. 

The emergency heat mode consumes a lot of excess energy. While it is great in the event of an emergency, it is unsuitable for everyday use. If this mode is engaged for an extended period of time, it can affect your monthly utility bill. 

Auxiliary heat – The details

Auxiliary heat is also known as supplemental heat or backup heat. This is the secondary source of heat used by a heat pump and is activated by the heat pump itself.

Heat pumps are designed to operate efficiently in moderate temperatures. During regular operation, a heat pump extracts heat from the outdoor air (or ground, depending on the type of heat pump) and transfers it indoors to provide heating

However, in cold weather or when the outdoor temperature drops significantly, the heat pump may struggle to extract enough heat from the outdoor air to maintain the desired indoor temperature. 

This is where auxiliary heat comes into play. 

How does it work?

When comparing aux heat vs emergency heat, auxiliary heat as the name suggests engages an additional or supplementary power source for your heating system. Auxiliary heat is typically an electric resistance heating element or a gas furnace that can provide additional heat when the heat pump alone is unable to meet the heating demand. 

When the heat pump’s efficiency drops due to extremely cold temperatures, typically around 35-40 degrees Fahrenheit, the auxiliary heat automatically kicks in to provide supplemental heat and help maintain indoor comfort.

Auxiliary heat is usually generated by electric resistance heating elements or a gas furnace, which supplements the heat generated by the heat pump to ensure your home remains at a comfortable temperature.

Things to keep in mind

It’s important to note that auxiliary heat can be more expensive to operate compared to the heat pump, as it often uses electricity or gas directly for heating, which may result in higher energy costs. Still, it does provide additional heating capacity in extremely cold conditions.

Therefore, it’s generally recommended to use auxiliary heat only when necessary, such as during extremely cold weather or when the heat pump is not able to keep up with the heating demand. Most modern heat pump systems are designed to automatically switch to auxiliary heat when needed.

Emergency heat – The details

Emergency heat, also known as “heat pump lockout” or “emergency heat mode,” is a setting on some heat pump systems that allows you to manually bypass the heat pump and use the auxiliary heat as the primary source of heat. This mode is often identifiable by the EM symbol. 

How does it work? 

The main difference between the two is that emergency heat does not kick in automatically. Instead, you can manually engage this setting. Typically it’s used in situations where the heat pump is malfunctioning and requires maintenance or repairs. 

It can also be used when you want to manually override the heat pump due to specific circumstances, such as during severely cold weather conditions, typically temperatures below 30 degrees Fahrenheit.

A difference between heat and EM heat, is that when you switch to emergency heat mode, the heat pump is completely shut off, and only the auxiliary heat is used to provide heat to your home. 

Things to keep in mind 

The emergency heat mode should only be used as a temporary solution. As a long-term heating strategy, it can be more expensive to operate due to the higher energy consumption of electric resistance heating.

Auxiliary heat vs emergency heat modes: Check your system

It’s important to note that not all heat pump systems have emergency heat capability, and the availability and operation of auxiliary and emergency heat may vary depending on the specific make and model of your heat pump system.

Homeowners often ask us, “Are emergency heat and auxiliary heat the same?” While they are similar in function, the key difference is that auxiliary heat is automatic whereas emergency heat mode is manually activated. While your system may have one mode, it may not have both. 

If you aren’t sure if your system has either mode, check your owner’s manual or ask a local HVAC technician. 

Need a new heating system? Call Anderson Air. 

While both auxiliary and emergency heat both provide supplemental heating from your HVAC heat pump, each has a particular application and use. 

Both options require a heat pump to run its supplemental power, whether it’s a gas or electric system and consequently, both options have additional energy requirements and will have an impact on your energy bills. 

If you are interested in installing a heat pump or require any heat pump maintenance or repairs, contact the Anderson Air team, and we’ll schedule a visit.

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