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Last Revised: 11/14/25
When winter temperatures dip into single digits, even the highest performing heating systems can be pushed to their limits. While most systems are designed to handle cold weather, a severe cold snap or unexpected issue can put strain on your equipment. In these rare situations, a reliable backup heat source offers an added layer of protection to keep your home safe and comfortable.
A backup heat source isn’t just a technical upgrade – it’s a smart safeguard. It ensures your family stays warm and secure, even when winter delivers its worst.
At Mattioni, we believe everyone deserves reliable, easy-to-understand guidance when it comes to staying safe and warm. With 75+ years of trusted service, we’re here to make complex heating systems simple – so you can make confident decisions about your home.
In this article, you’ll learn what a backup heat source is, when it’s used, how it affects energy costs, and what to do if it starts running more than it should. We’ll also share practical advice on how to prepare your heating system (and its backup) before the cold weather hits.
Here’s what we’ll cover:
- What a backup heat source does
- The most common types
- The cost of using backup heat
- How to prep your heating system for winter
Let’s take a closer look at what exactly a backup heat source is.
What is a Backup Heat Source?
A backup heat source is a secondary method of heating that activates when your main system (like a heat pump) can’t keep your home warm on its own. It’s built to step in during extreme weather, malfunctions, or when the primary source reaches its performance limits.
For example, heat pumps work efficiently in moderately cold temperatures, but their ability to extract heat from the outside air decreases significantly when temperatures fall below 20-25°F. At that point, the system may automatically switch to a backup source to maintain your indoor temperature. Backup heat kicks in if your furnace stops working or can’t meet the thermostat’s demand during a cold snap.
In other words, backup heat ensures your comfort doesn’t depend on ideal conditions.
Types of Backup Heat Sources in Homes
Backup heat comes in several forms, depending on your home’s HVAC setup. Here are the most common:
- Electric Resistance Heat (Heating Strips): Often built into heat pump systems, this form of backup uses electric coils to generate heat – it’s effective, but also energy-intensive.
- Gas Furnace Backup (Dual-Fuel System): Homes in colder climates typically benefit the most from dual-fuel systems. An electric heat pump is paired with a gas furnace, and when temperatures drop below a set point, the system switches to gas heat. It’s usually more efficient than electric heating strips.
- Portable or Supplemental Heaters: Separate from your central HVAC system, some homeowners use space heaters or wood stoves as emergency heat sources. These should be used carefully and with proper ventilation.
Knowing which type you can have can help you understand how your system will behave in winter – and what to watch out for.
Does Every Home Have – or Need – a Backup Heat Source?
Not every heating system includes a built-in backup, but many should – especially in areas with below-freezing winter temperatures.
Homes with heat pumps almost always need backup heat because these systems experience diminishing efficiency in the extreme cold. By the same token, homes with a gas or oil furnace typically don’t need a secondary source unless the house has a poor insulation rating (drafty) where the primary system can’t fully meet demand.
You can check your system by:
- Looking for “aux heat” or “emergency heat” indicators on your thermostat
- Reviewing your HVAC system’s specs
- Asking your HVAC technician during your next tune-up
If you’re unsure whether your home has backup heat – or needs it – it’s worth scheduling a system evaluation before winter fully sets in.
How Backup Heat Affects Energy Use and Costs
Backup heat sources – especially electric resistance heat – can be significantly more expensive to run than your primary system. When your heat pump switches to backup mode, it typically uses more energy to produce the same amount of warmth. That means higher utility bills, particularly during prolonged cold spells.
A sudden spike in your winter energy bills may be a sign that your system is relying on backup heat more than it should. This could be due to low temperatures, but it might also point to an issue like a dirty air filter, refrigerant loss, or even a failing component in your primary heat source.
The best way to get to the root of high energy bills? Have an HVAC pro out for a seasonal inspection and tune-up.
What If My Backup Heat Is Always Running?
Backup heat should be just that – a backup. If it’s on constantly, it could mean your primary system isn’t operating correctly or isn’t sized properly for your home.
Common causes include:
- A failing heat pump or furnace
- Incorrect thermostat settings, such as the emergency heat mode being left on
- Airflow restrictions, like clogged filters or blocked vents
- A malfunctioning temperature sensor or control board
If your backup heat is running more than usual, or your home isn’t staying consistently warm, it’s time to call a professional. Ignoring the issue could lead to higher energy bills and even system failure when you need it most.
How to Prepare Your Heating System (and Backup) for Winter
The best way to avoid cold-weather surprises is to prepare your system before winter sets in. That includes:
- Scheduling a professional HVAC inspection to check system performance and confirm your backup heat is functional
- Changing air filters and clearing vents to improve airflow
- Testing your thermostat and backup heat mode early in the season
- Asking your technician about system efficiency, especially if your unit is more than 10 years old
At Mattioni, our comprehensive winter tune-ups ensure your system is ready – primary and backup included. We help homeowners avoid mid-winter breakdowns and keep energy bills under control.
Click here for more seasonal homeownership prep
Stay Warm, Stay Prepared with Mattioni
Understanding how your backup heat works – and when it should be used – can protect your comfort, your energy budget, and your peace of mind this winter. From identifying system limitations to ensuring everything is running efficiently, backup heat is a key part of a well-prepared HVAC setup.
With over 75 years of trusted experience, Mattioni is here to help. Our expert technicians can evaluate your system, ensure your backup heat is ready, and make sure you’re equipped for whatever winter brings.
Need a winter heating checkup or want to be sure your backup heat is working properly? Call our friendly team at (610) 400-8510 or schedule your service with Mattioni today.
