By Anne Fonda

Multipoise in HVAC refers to a multipoise furnace, which is a gas furnace that can be installed in multiple positions to accommodate a variety of spaces.

Trane’s 80% furnaces are  4-way multipoise, meaning they can be installed in one of 4 configurations, including:

• Upflow
• Downflow
• Horizontal Right
• Horizontal Left

Trane’s 90%+ furnaces are considered 3-way multipoise, meaning one model can be installed in upflow, horizontal left, and horizontal right configuration.

The configurations refer to how warm air flows from the furnace and into your ductwork. All gas furnaces operate similarly - burning fuel to heat the air before blowing warm air into the ductwork. The difference in these furnaces is the direction in which the air flows into the furnace and then out after it’s been heated.

In the upflow position, the furnace pulls in air at the bottom of the unit, passes it over the heat exchanger, and blows the heated air up and out through the top of the unit and into the ductwork. If you have a basement, this furnace installation configuration is probably the most efficient for your home, because hot air naturally rises.

In the downflow position, the furnace takes in cool air at the top and heats the air over a heat exchanger. Then, it releases warm air down at the bottom. This warm air then circulates through the ductwork system to heat your home.  An attic is the most likely location for a downflow furnace.

Since heat naturally rises, a downflow furnace has to work harder, leading to more wear and tear. A furnace with this airflow configuration may also be less energy efficient.

In the horizontal position, the unit is lying on its side and the air flows in from one end and out the other end. A horizontal flow furnace configuration is most common in attics and crawl spaces.

The best airflow configuration is the one that works best with where you need to locate your furnace. An experienced HVAC company can help you determine the proper location of the furnace in new construction. For an existing home, changing the location of the furnace can be cost-prohibitive.

It’s important to work with an HVAC professional who knows what furnace models can be installed the way they need to be in your home. There are other important factors to consider when choosing a new furnace including:

• Energy efficiency/AFUE rating
• Number of heating stages
• Fuel type
• Price range

To help you decide what furnace is right for your home, learn more about variable speed vs single-stage and two-stage systems.

Whether you’re building a new home or upgrading your HVAC system, it’s important to work with an experienced HVAC installer. You can get the highest quality equipment, but if it’s not installed properly, you’ll run into trouble quickly.

To keep your new system running at peak efficiency, be sure to follow our maintenance tips.

Anne Fonda, Content Writer

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A Content Writer with Trane Technologies, Anne Fonda researches topics and writes for Trane® and associated residential HVAC brands. She works in collaboration with Trane Technologies subject matter experts, offering easy-to-understand, informative content on complex topics. Her goal is to help consumers make informed decisions on the products and services they need.

She has written for HVAC and other service provider websites for over 16 years. Before transitioning to web content writing, Anne had a 14-year stint as an award-winning journalist. She graduated cum laude from the University of Missouri-Columbia School of Journalism.

When she’s not working, Anne enjoys playing word games, reading, gardening, spending time with family, and visiting gardens and museums.

Expert review by John Kim, Senior Product Manager, Furnaces