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Dual Fuel Heat Pump: How Does It Work?

With a dual fuel heat pump, you get the best of both HVAC worlds: hot or cold air when you need it most. This hybrid heating and cooling system combines a traditional heat pump with a furnace to provide your home with an energy efficient HVAC device that you can use all year long. Not only does a dual fuel heat pump save energy and help the environment, but it also saves you time and money on utility bills.

What is a dual fuel heating system?

A dual fuel heating system is a hybrid system made-up of both an electric heat pump and a gas furnace. The system alternates between using each of the two devices, depending on the season, temperature and the function needed, to maximize efficiency and effectively heat and cool your home all year long.

The heat pump in the system works like a central air conditioner in the summer months by transferring hot air out of your home until your thermostat reads your desired temperature. The heat pump also does the majority of the work in the fall and spring months by providing cost-efficient heat during milder temperatures.

The dual fuel furnace takes over and works to heat your entire home when the temperature takes a dip during the cold, winter months. Furnaces have one function, converting fuel into heat quickly and efficiently. When it’s cold outside, the furnace in your dual fuel system will do just that.

Furnaces vs. heat pumps vs. dual fuel

Understanding the differences among these three HVAC devices will help you decide which is right for your home!

Furnaces

A furnace.

A furnace is a good ol’ fashioned heating device. It works by burning a fuel source, like propane or natural gas, to make heat. That heat is then combined with air from the home to warm it, then that warm air is re-distributed throughout the home. Furnaces only produce heat, so homeowners typically need a separate air conditioning system in their home for the cooler months.

Furnaces are only about 95% energy efficient, but they do have a longer lifespan (more than 20 years) than other heating devices because they’re used for only a few months out of the year. They’re not too expensive to install, but keep in mind that your home does need to have access to natural gas or propane for a furnace to function. If it doesn’t, the process to access a natural gas source will drive up the installation cost.

Heat pumps

A heat pump.

Heat pumps perform both heating and cooling functions, so you only need to have one HVAC device to cover you all year long. Heat pumps are flexible systems, so they’re able to adapt to the weather outside. For instance, when it’s cold out, heat pumps extract whatever heat is in the outside air and transfer it into the home. When the temperatures are warmer, they switch to a cooling function by removing hot air from the home. Heat pumps have a shorter lifespan than furnaces (around 15 years) because they work all year long moving air around to reach your desired temperature.

When temperatures outside are close to freezing, heat pumps have to work for more time to bring heat into your home, which can drive up your utility bills. But, they are more energy efficient overall than most HVAC devices — they can reduce your electricity use for heating by about 50% compared to furnaces, according to the Department of Energy— and make sense for homeowners in year-round mild climates.

Dual fuel systems

A hybrid system

As we mentioned earlier, dual fuel systems are a combination HVAC system with both a heat pump and a furnace. The dual fuel system uses the heat pump in hot or mild temperatures (about 40°F and higher) and the furnace in colder temperatures (about 39°F and below). It switches between the two depending on which is more efficient for the circumstances, which saves time and energy in getting your home to the desired temperature. Dual fuel systems are great for any type of climate and function year-round. Plus, because each piece only works when it's optimal, dual fuel systems have a life expectancy between 20 and 25 years!

When does a dual fuel heat pump make sense?

If you live in a place where the temperature is always changing

Dual fuel heat pumps are best for places that experience all four seasons and varying temperatures. If you live in a place that’s cold the majority of the time, a furnace can help provide heat, and a lot of it, at a rapid pace. For those who live in hotter or more mild climates, heat pumps make the most sense because they function best in warm to hot temperatures.

Dual fuel systems are for people who experience both ends of the temperature spectrum. A furnace only heats, so if you live through changing climates, you’ll need to invest in another HVAC system to meet your needs. While heat pumps both heat and cool, they have to work overtime at extremely low temperatures, which isn’t always the most cost or energy effective solution. Dual fuel heat pumps take the best qualities of both systems to tackle whatever climate you may wake up to.

If local laws encourage energy efficiency

Furnaces use energy sources like propane and natural gas to burn heat, which isn’t always the most environmentally-friendly option. States are beginning to pass new laws that encourage and reward energy efficiency in HVAC, like California’s 2022 Energy Code. Heat pumps are the star of the show in California’s new code, using the energy efficiency rates of heat pumps as the performance standard baseline for heating and cooling in all homes and some commercial spaces. Heat pumps are typically the gold standard in terms of energy efficiency, because they just transfer energy instead of making it from scratch. If your state’s energy efficiency laws are headed in the same direction as California, it might be worth upgrading your current HVAC system to a dual fuel to keep up with the changing times.

If dry, hot heat in the winter impacts your personal comfort

If you’re using a furnace in the winter and experiencing dry, chapped skin while inside your home, your HVAC system could be the cause. The gas heat that furnaces produce and put into your home is a higher temperature than heat produced from an electrical source. This hot, dry heat can dry out and chap sensitive skin. If this sounds like a problem you face, you may want to consider upgrading to a dual fuel system with “cooler” heat for a more comfortable living experience, while still getting that hot heat when it's needed.

How can a dual fuel heat pump save you energy and money?

The ability for a dual fuel heat pump to switch between a furnace and a heat pump is what saves you energy, time and money. Like we mentioned earlier, a furnace isn’t needed in hot temperatures (because it only produces heat) and a heat pump has to work overtime in extremely cold temperatures. Instead of letting a regular heat pump do the extra work in the winter, a dual fuel system lets the furnace do the heavy lifting. This means, the heat pump isn’t expending unnecessary energy to do a job a furnace could do quicker and more efficiently. On the flip side, a heat pump can warm your home in a more energy-efficient way than a furnace when it's just cool outside, and a dual fuel system lets it do just that.

All this switching between functions doesn’t only save energy, but it also saves time and money. By allowing the best device to heat or cool your home at the best time, a dual fuel system gets your home to your desired temperature faster. Not to mention, less energy wasted from your HVAC systems means less money wasted on utility bills for you.

Dual fuel heat pumps are a triple win for homeowners.

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