Pros and Cons of a Modulating Furnace

When designing your dream home, most people tend to fixate on the house’s immediately visible aspects.

Despite that, the home’s furnace is an important thing to consider, especially if you want to be as energy-efficient as possible. Finding the right gas furnace is crucial and one great option to consider is the modulating furnace

Below is a compiled list of the pros and cons to consider when installing a modulating furnace in your home.

Consistent heat distributionVery expensive
Multiple output optionsMore frequent noise
Low energy consumption
Various temperature adjustments based on the weather
Superior air quality

We’ll break down the specifics of how modulating furnaces can work for your home, as well as what to expect when selecting the ideal gas furnace.

Even if you’re not a furnace enthusiast, this will make it easy to understand the benefits and drawbacks of modulating furnaces and their competitors below.

How Does a Modulating Furnace Work?

As a gas furnace, you can already expect high energy efficiency, but the modulating furnace takes that expectation to a whole new level.

A high-efficiency unit like the modulating furnace works by bringing in air from outside your house for combustion.

That process works exceptionally well for people who put their furnaces in the house’s attic or other sealed areas.

Standard furnaces work best in ventilated areas using the air inside as combustion air, but it is a safety hazard in an unvented space.

It can lead to carbon monoxide getting into your home. There are two types of gas furnaces, conventional and condensing. 

Conventional gas furnaces burn gas via one heat exchanger so that the excess heat can escape either through walls or a chimney in vapor form.

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Condensing gas furnaces have two heat exchangers, the second capturing the extra heat and putting it to work.

Condensing gas furnaces are considered more energy efficient because of that. 

As the name suggests, a modulating furnace has a valve used to control how much heat is expelled precisely.

A modulating furnace is a condensing gas furnace and the combination of precision control over temperature levels and the second heat exchanger means that absolutely no energy is ever wasted. 

What Makes a Modulating Furnace Worth It?

Many high-tech features and options are inherent in most modulating furnaces that give homeowners a ton of bang for their buck.

There is a collection of the main benefits for customers here. 

Consistent Heat Distribution

By effectively utilizing two heat exchangers, the modulating furnace can maximize the heat output for its given energy.

That means you don’t have to worry about cold spots lingering around the house or suddenly having the temperature of one room drop while the furnace sends heat somewhere else.

Your entire home can stay warm and cozy, even on the coldest days.

Consistent heat distribution as a feature is most effective in homes with multiple stories.

Typically, in a two-story house, the upstairs will tend to be warmer because heat rises.

That can make it annoying and waste energy when you set the thermostat higher to compensate.

A modulating furnace will ensure that you don’t have hot and cold spots, no matter how large your house is. 

Additionally, the temperature sensor in the furnace senses as your house slowly warms up and automatically decreases the output and how much energy is being used to run it.

As the speed of the blower fan increases, the furnace reduces gas flow to the burners.

Not only does that save you money, but it also keeps your house at the temperature you set without much variation over the day. 

Multiple Output Options

The modulating furnace allows you to control the heat output at any given time.

You can adjust the temperature settings in your thermostat and decide how much heat your furnace will be giving out.

On more mild days, you won’t have to be concerned about using expensive energy just to slightly warm things up. 

Superior Air Quality

One aspect of the modulating furnace that helps it stand out from the crowd is its ability to run the furnace fan even when it isn’t actively expelling heat.

The fan works to circulate the air, so if you suffer from allergies or other air quality issues, this furnace can reduce those pesky sneezes. 

High Energy Efficiency

All gas furnaces are given an annual fuel utilization efficiency, or AFUE, rating. AFUE measures the ratio of yearly heat output to the annual fossil fuel energy the furnace consumes.

For a modulating furnace, you can achieve an AFUE of 98%! That’s a pretty impressive ratio, especially compared to other types of furnaces.

Plus, most models come with a variable speed ECM motor pre-installed, which allows you to keep the amount of electrical energy needed to power the furnace as low as possible.

That ECM motor also helps maintain a consistent temperature. If you’re looking to maximize the energy you can get from your furnace, then a modulating model is right for you.

Weather Intuition

The modulating furnace even has the capability to automatically set your heating and fan outputs based on the weather outside.

It senses the temperature outside and adjusts your house accordingly so you can stay snuggled up on chilly days and not have to worry about turning the furnace off when it’s hot out. 

What Are Some Drawbacks to a Modulating Furnace?

Despite all of the benefits that we have just listed, there are a few significant drawbacks to the modulating furnace that homeowners need to factor into their decision. These consist of the price and consistent levels of noise. 

Initial Cost of the Furnace

The only real drawback to a modulating furnace is the initial outlay. Because of the modulating furnace’s clear superiority and ability to put all of your energy to work, it costs a pretty penny to have installed.

The high-end features like sensing the weather and intuiting your home’s ideal temperature do not come cheap. 

Installation Costs

However, your expenditure doesn’t end with purchasing the furnace. You will also need an HVAC contractor to install piping for the combustion air and drainage for the condensate.

The downside of having two heat exchangers is that the extra air cools in the second pipe and becomes condensation that needs a place to drain out. 

These installation costs are only necessary for your first high-efficiency furnace. If you are upgrading now or plan to in the future, you won’t need to reinstall or change those pipes down the line. 

For homeowners who plan to recoup their costs in saving money on their energy-efficient furnaces and who have the money to pay for the furnace, this is a no-brainer.

Frequent Noises

Some people who have switched from alternative models to a modulating furnace have noticed that it is louder than their previous furnace.

Still, the noise isn’t more audible; it just happens more often. When the furnace shuts off completely, the house is silent.

For people who had single-stage furnaces, much of the time, the furnace was off and, therefore, quiet. 

Due to its nature, modulating furnaces run almost continuously and are always making noise.

If you have been used to a mostly silent furnace during the warmer months of the year, this can be a difficult adjustment to make. 

Alternatives to a Modulating Furnace

If you can’t justify a modulating furnace’s expense and are looking for other gas furnace alternatives, this article has put together a list of your other options and what they can offer you as a homeowner. 

Single Stage Furnace

Unlike the modulating furnace, a single-stage furnace only goes at the highest possible output.

The homeowner has no control over the amount of heat coming out, which means that this isn’t as energy-efficient as a modulating furnace.

The valve is either open or shut, with no in-between. 

However, for people who live in places that drop to freezing temperatures, this furnace can work wonders at keeping you warm at night.

Although single-stage furnaces typically have an AFUE of 80-85%, some models include an ECM motor that can lower the amount of electrical energy you need to power the furnace. 

Inexpensive model of furnaceMore energy consumed
Highest level of heatingNo adjustments possible
Not recommended for temperate climates

Two-Stage Furnace

A two-stage furnace is capable of handling multiple heat settings. Although you aren’t given nearly as many choices for your settings as with the modulating furnace, the two-stage furnace has three options: high, medium, and off.

The medium setting works well for people who don’t need quite as much heat and would like to save energy. 

By allowing the homeowner to adjust the temperature settings, you can achieve an AFUE of up to 96%.

Not quite as high as the modulating furnace, but close. Like the single-stage furnace, higher-end two-stage furnaces will come equipped with an ECM motor to reduce your need for electrical energy to power the furnace. 

Moderately pricedFewer available settings
Two output options
Lower energy consumption

In Summary

Furnaces have come a long way since the olden days of shoveling coal and throwing logs onto a roaring fire.

Depending on your geographical location and energy consumption needs, a modulating furnace can be the cutting-edge solution that is perfect for your dream house.