Residential Gas Furnace Sizing

Overall efficiency p efficiency within a model group will tend to vary by the size capacity of the unit.

Residential gas furnace sizing. Finding the right sized gas furnace for a home often runs into the goldilocks problem some are too large and some are too small. A gas furnace made in the early 1970s typically has an afue of about 65 percent. Next if you need to calculate the output you need on a gas furnace simply multiply its efficiency by its listed input rating for the btu output of heat. The lowest efficiency allowed by law for new gas furnaces is 78 percent and some new models achieve 97 percent.

Different furnaces of the same input btu have different efficiencies measured in percentages. Use our guide to size up your home to find the perfect furnace. How to determine proper furnace size. How to estimate a gas furnace size.

From our top of the line evolution system furnaces through the solidly built legacy line of bryant furnaces you can find the blend of dependable heating performance quiet operation and exceptional comfort and energy savings that is right for your home. In addition to weather and climate the size of your home also has a direct impact on the size furnace you ll need. Typical residential gas furnaces will be available in various sizes between 44 000 btu h and up to 120 000 btu h. Furnaces are rated by the amount of fuel energy consumed when running called input btu.

Getting the right one. That means the furnace will produce 80 000 btu of heat. A btu is equal to the amount of. Understanding furnace efficiency ratings once your carrier dealer has completed a load calculation to determine the proper size furnace for your home you still have decisions to make.

Most furnaces are offered in 15 000 20 000 btu increments so you just need to get close in terms of sizing. The more space you need to heat the more heat output you ll need to heat the entire. Residential gas furnaces are available in a number of sizes and are measured in british thermal units or btus per hour. If the furnace you selected is more than 10 below your heating requirement we suggest you go up to the next size.

Some products like furnaces may also be affected by installation orientation horizontal upflow or downflow or even by the nozzle used in installation as is the case with boilers and oil furnaces. 100 000 btu input x 80 efficiency. If a furnace is listed with an input rating of 100 000 btu s and an efficiency rating of 80 it would produce. For example a furnace with an input btu can have an efficiency of 80.