Upflow vs Downflow Furnace: What’s the Difference and Which One Should You Choose?

One important decision you’ll face when installing a new furnace in your home is choosing the right type. 

The main difference between an upflow and a downflow furnace lies in the direction the air flows. However, your home’s layout and the amount of heat you use each year also play a role in determining what’s best for you.

To help you make a more informed choice, this guide breaks down everything you need to know about both furnace types. 

Upflow vs Downflow Furnace in a Glance

We’ve compared upflow vs downflow furnaces based on cost, installation, efficiency, long-term maintenance, and listed out their pros and cons. 

Whether you’re talking about commercial HVAC systems or not, both upflow and downflow models fall under forced-air heating systems.

By the time you’re done reading, you’ll have a clearer idea of which one works better for your home. Let’s look at upflow and downflow furnaces in more detail. 

How Upflow Furnaces Work

An upflow furnace is designed to push heated air upward through your home. It pulls in cooler air from the bottom, heats it, and sends the warm air up through the supply ducts. This is perfect if your ducts are located above the furnace, like in a basement setup.

The blower sits at the bottom of the unit, while the heat exchanger or heating coils are above it. 

Once the air is warmed, it naturally moves upward, which can make the heating process more efficient, especially in colder climates.

Pros

1. Ideal for basement installations

2. Warm air rises naturally, which is more efficient in cold regions

3. Easier access for servicing in basement setups

4. Better airflow in multi-story homes

5. Compatible with high-efficiency models

Cons

1. Not suitable for attic or upper-level installs

2. May require extra ductwork if installed on upper floors

3. Takes up floor space in the basement

4. More difficult to install in slab-on-grade homes

How Downflow Furnaces Work

A downflow furnace pushes heated air downward. It pulls in cool air from the top, warms it using the heat exchanger or heating coils, and then sends the heated air down through ducts located below the unit. 

This setup is best if your furnace is going in the attic or on an upper floor, with ductwork running underneath.

Pros

1. Best for attic or upper-floor installations

2. Works well with floor duct systems

3. Keeps lower levels warmer

4. Saves the basement or crawl space 

Cons

1. Heated air goes down. Thus, less natural airflow

2. Not ideal for basement setups

3. It can be harder to service in tight attic spaces

4. It may cost more to install if ducts need rerouting

Meanwhile, in modern forced-air systems, the efficiency difference between upflow and downflow is minimal because powerful blowers overcome natural convection effects.

Side-by-Side Comparison: Upflow vs Downflow Furnace

To determine which of these units you choose, consider these factors upon which we’ve compared them on;

1. Ductwork and Home Layout Compatibility

Ductwork design plays a major role in furnace choice. Upflow systems are more compatible with homes that have ceiling vents or supply registers located on or near the upper part of the walls. 

Downflow furnaces are better suited for homes with floor vents, slab foundations, or limited attic access to the ductwork. 

However, pushing warm air downward goes against the natural movement of heat, which can sometimes lead to uneven heating, especially in larger homes or those with high ceilings. 

If the ductwork isn’t optimized, you might experience slower warm-up times or cold spots.

2. Energy Efficiency and Performance

Upflow furnaces generally have a slight edge in efficiency in cold climates because they align with the natural direction of heat rising. Less effort is required from the blower motor to push the heated air, resulting in reduced energy use over time. 

That said, with modern multi-speed blowers and two-stage designs, this difference is often negligible, especially in well-insulated homes.

3. The Cost

Downflow furnaces are priced very similarly to upflow furnaces. Upflow units are usually less expensive to install if your home already has a basement or crawlspace, since less duct rerouting is required. The units themselves are competitively priced.  At HVAC Store, units start at $1,152. 

Meanwhile, downflow units can be more costly to install, particularly in attic spaces. Extra framing, drain lines, insulation, and combustion air allowances may be required to meet local codes. Accessibility during installation and servicing also affects labour costs.

The cost to install a downflow furnace can range from $3,000 to $7,000, according to HomeGuide, a platform that connects homeowners with local service professionals.  

NOTE: 

• If your home’s existing ductwork was initially designed for a different furnace orientation, modifying it for an incompatible unit can add hundreds (or even thousands) to your total cost.

Which One Should You Choose? 

Go with an upflow furnace if your home has a basement or crawlspace, and your ductwork runs overhead or through the attic. Why? Upflow units are designed to blow hot air upward, which matches the natural direction heat wants to go. 

That means your blower works less, your rooms warm faster, and your energy bills stay lower.

However, if your home is built on a slab with no basement and all your ductwork is located in the floor or lower part of the home, then opt for a downflow furnace. It’s made to push warm air downward.

Pro Tip: 

• If your install location is cramped or you’re unsure about future layout changes, a multi-positional furnace is a smart, flexible choice. They can be installed in upflow, downflow, or horizontal configurations, depending on your specific needs. They come with adaptable venting and drain setups.

Another flexible option is Horizontal furnaces. They are installed on their side, usually in crawlspaces, attics, or tight utility closets where vertical space is limited. Air flows from left to right or right to left, rather than up or down.

Explore Upflow and Downflow Furnace Options at HVAC Store

If you’re shopping for a new furnace, HVAC Store offers a wide range of solid options to choose from. We stock both upflow and downflow models, so no matter where your system’s going (attic, basement, or anywhere else), you’ll find something that fits.

Our team is familiar with these systems and can guide you through the pros and cons based on your specific setup. 

We carry only brands we trust, including Goodman and ACiQ, and we’re here to ensure you get a unit that works well for your home.