Gas furnaces use gas to heat your home. In order to find the perfect furnace for your space, you will first need to calculate the square footage of your home in order to estimate how many BTUs the furnace will need to possess, whether you want standard or high efficiency, and what orientation the furnace will need to be.
Here is how to find the proper tonnage for your gas furnace:
Warmest climates: 30-35 BTUs per square foot
Warm climates: 35-40 BTUs per square foot
Mild climates: 40-45 BTUs per square foot
Cold climates: 45-50 BTUs per square foot
Coldest climates: 50-60 BTUs per square foot
You have chosen a 40,000 BTU gas furnace.
You’ll need to decide which orientation you’d like to choose for your gas furnace. We offer downflow horizontal or upflow horizontal models. Upflow furnaces are often installed in the basement or in the closet, where the ductwork is located above the level of installation. Contrarily, downflow systems are installed in crawl spaces or in areas where the ductwork is below the level of installation.
You also have the option to choose between a “standard efficiency” gas furnace or a “high efficiency” gas furnace. On our site, “standard efficiency” stands for gas furnaces that are 80% efficient and “high efficiency” gas furnaces are those that are 92% efficiency or higher.
Disclaimer: Before making a purchase, you should always check first with your qualified installer to figure out what unit is best for your home or space.