What Is a Modulating Furnace and How Does It Work?

Heating is important in every home, especially during the frigid winter months. As such, you need a heating system that will maintain comfortable indoor temperatures throughout the cold season.

Furnaces are among the most effective options for keeping houses warm and comfortable. One of the best types of furnaces is the modulating furnace. This type of heating system boasts energy efficiency and better temperature control.

A modulating furnace isn’t cheap, but the long-term benefits are definitely worth it. Read on and learn all about this type of heating system.

What is a modulating furnace?

If you have ever come across a gas furnace with a modulating valve, it’s the perfect example of a modulating furnace. A modulating furnace also comprises a variable-speed blower.

A modulating furnace is a popular heating system that comes with a burner, and it can adjust or control the amount of fuel used. Every time you turn it on, energy consumption is adjusted continually to ensure efficiency. This adjustment helps make heating your home more cost-effective.

Unlike common one or two-stage furnaces, a modulating furnace is all about energy efficiency. Homeowners can have better temperature control with this type of heating system.

How does a modulating gas furnace work?

So, how does a modulating furnace work?

When you turn on a modulating furnace, it adjusts fuel consumption to ensure you have the best temperature at a minimal cost. In other words, it starts with a full capacity output but adjusts as your house or space heats up. This way, it prevents wasted heat and fuel. 

The two main parts of the heating system responsible for this effect are the blower fan and gas valve. The blower fan speed changes depending on your home’s heating needs.

While the single-stage furnace has two settings and the two-stage furnace has three, a modulating gas furnace has numerous settings that ensure proper temperature control in your home. The best part is you can enjoy consistent temperatures throughout.

Pros and cons of a modulating furnace


1. Consistent temperature setting

A major issue with a one-stage or two-stage furnace is the temperature settings. Both types of gas furnaces are excellent heating systems for residential properties. However, they only turn on after temperatures have dropped four degrees.

Once the temperature is that low, the furnace will turn on and run until it’s back up to a degree or two above the set temperature. This often causes noticeable temperature swings in your home.

Fortunately, you can overcome this matter by installing a modulating furnace in your home. Once it’s set up and running, this heating system keeps the temperature within a consistent 0.5- to 1-degree range above what’s on the thermostat.

2. Improves indoor air quality

During winter, the furnace becomes one of the most important items in a home. While furnaces are essential, you might experience poor indoor air quality issues. Usually, this happens because of the high blower setting.

If the blower setting is higher, so is the pressure of air flowing into your home. Higher air pressure tends to strain the air filter, which can cause poor filter efficiency.

However, when you install a modulated furnace in your home, you can have better air quality. This heating system runs at a low blower setting, so there’s lower air pressure. It gives the air filter enough time to clean the air before it’s pushed through your home.

3. Energy efficiency

A modulating gas furnace’s third and most important benefit is better energy efficiency. Often, issues like short cycling cause one-stage and two-stage furnaces to use lots of energy. But, a modulating furnace lowers fuel consumption, reducing your energy costs.


1. Expensive

The long-term benefits of a modulating furnace are quite alluring. This is because you can end up lowering your energy bill even after a short period of time.

However, be ready to spend a good amount of money buying and installing the heating system in your home. The initial installation cost is fairly high, and you must hire an HVAC expert to install it for you.

2. Noisier heating system

A modulating furnace can be a bit noisier than other types of furnaces. While the noise isn’t very loud, it’s more frequent and can be irritating to some

What is the AFUE of a modulating furnace?

As mentioned earlier, energy efficiency is one of the key benefits of a modulating furnace. This works for all types of energy, including gas, electric, propane, and oil. Homeowners notice that this heating system doesn’t need much energy to keep a home comfortable.

If you still need more convincing, check out the AFUE percentage of modulating furnaces. A quality modulating gas furnace has an AFUE % range from 94 to 98%. This is much higher than traditional gas furnaces and will guarantee better energy efficiency in your home.

How much does a modulating furnace cost?

While modulated furnaces have many benefits, they aren’t the cheapest option. The purchase price will depend on the model and can range from $1300 to $7000.

Once you note the price of the heating system, add the cost of hiring an HVAC expert to install it. Different HVAC companies have varying rates, so do your research in advance to get an average. 

Does a modulating furnace improve comfort?

Yes, a modulating furnace improves comfort in your home. In fact, the more you use this heating system, the more you can appreciate the comfort it offers.

With a one-stage or two-stage furnace, discomfort in your home often happens during the off settings. This is because these types of furnaces only have on and off settings.

Fortunately, there are more settings available on a modulating furnace, which will contribute to increased comfort. It works efficiently to ensure consistent air and temperature in your home.

Is a modulating furnace worth it?

Considering the high installation cost, many homeowners often ask: “is a modulating furnace worth it?” And the answer is yes!

A modulating furnace has many benefits making it a great investment for your home. For instance, consider the energy efficiency that comes with this heating system. It consumes less fuel, so your monthly gas bill is lower.

Also, it’s able to maintain the ideal temperatures throughout the house without any cold gaps. So, while the initial investment can be steep, the comfort and savings that follow are worth every dime.


If you’re interested in installing a modulating furnace, we recommend asking a professional first. A licensed technician will be able to tell you if it’s suitable for your living space and how much the installation will cost.

Schedule an appointment with a professional at Anderson Air today. 

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